Illumination device for multi-beam illumination

Abstract

An illumination device comprises a plurality of lighting units configured to emit a respective light beam in a respective light beam direction. A plurality of light sensors is configured to sense light in a respective sensor field of view in a respective sensor direction. A controller is configured to perform a calibration procedure that comprises receiving sensor signals, each sensor signal representing a light level in each respective sensor direction. The sensor signals are analyzed to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction. The lighting units are controlled to emit a respective light beam such that, for each light beam direction, if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction is reduced.

Description

[0001] 2024PF80142 1

[0002] Illumination device for multi-beam illumination

[0003] FIELD OF THE INVENTION

[0004] The present invention generally relates to illumination devices. More specifically, the present invention is related to an illumination device comprising a plurality of lighting units and a plurality of sensors and a controller configured to control the lighting units.

[0005] BACKGROUND OF THE INVENTION

[0006] Outdoor illumination devices such as garden lights typically highlight elements of a garden: trees, plants, walls, pathways or decorative objects. If not well aimed, such outdoor illumination devices can lead to light pollution of the night sky, or light trespassing that annoys neighbors. An additional drawback is therefore waste of energy when badly aimed illumination devices emit light in undesired directions.

[0007] With regard to garden lights, even for well-aimed garden lights, the situation may change over time because elements in the garden change with the passage of time: plants grow, die, or are cut, leaves fall off trees in winter, furniture or decorative objects are moved, etc. Furthermore, especially with regard to solar power lighting, the illumination devices may be moved around in the garden, which easily results in light emission in unwanted directions, especially for illumination devices that shine upwards or sideways.

[0008] Although outdoor scenarios may be considered as most relevant, indoor scenarios may also be relevant. For example in a case where illumination in one or more directions where windows are located is to be avoided.

[0009] SUMMARY OF THE INVENTION

[0010] It is of interest to provide an illumination device that is capable of overcoming the drawbacks of prior art devices.

[0011] This and other objects are achieved in a first aspect by providing an illumination device having the features of the appended independent claim. Preferred embodiments are defined in the appended dependent claims. 2024PF80142 2

[0012] Hence, according to the present invention there is provided an illumination device comprising a plurality of lighting units, each lighting unit being configured to emit a respective light beam in a respective light beam direction. A plurality of light sensors is configured to sense light in a respective sensor field of view in a respective sensor direction. A controller is configured to perform a calibration procedure that comprises receiving sensor signals from the light sensors, each sensor signal representing a light level in each respective sensor direction. The sensor signals are analyzed to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction. The lighting units are controlled to emit a respective light beam such that, for each light beam direction, if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction is reduced.

[0013] Such an illumination system overcomes drawbacks of the prior art, for example by being very flexible in terms of adapting illumination to varying conditions in the environment where the illumination system is arranged. For example, in an outdoor environment such as a garden, elements may change with time and thereby creating a changing reflection pattern. For example, plants grow, die, or are cut, leaves fall off trees in winter, furniture or decorative objects are moved. Also, in particular with regard to solar power illumination devices, the devices themselves according to the invention may be moved around in the garden without leading to light emission in unwanted directions, especially for lights that shine upwards or sideways.

[0014] In various embodiments, the controller may be configured to control the lighting units to emit a respective light beam such that, for each light beam direction, if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction is adjusted by a factor that is proportional to the reflection intensity value for the light beam direction.

[0015] In other words, a dimming level of the lighting units may be set to a level that is proportional to the intensity of the reflected light, resulting in an enhancement of the contrast of light reflected from different directions.

[0016] In various embodiments, the controller may be configured to control the lighting units to emit a respective light beam such that, for each light beam direction, if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction is adjusted by a factor that is negatively proportional to the reflection intensity value for the light beam direction. 2024PF80142 3

[0017] In other words, the dimming level of the lighting units may be set to a level that is negatively proportional to the intensity of the reflected light, resulting in a reduction of the contrast of light reflected from different directions.

[0018] In various embodiments, the controller may be configured to control the lighting units to emit a respective light beam such that, for each light beam direction, if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction is adjusted by a factor that is inversely proportional to the reflection intensity value for the light beam direction.

[0019] In other words, the dimming level of the lighting units may be set to a level that is inversely proportional to the intensity of the reflected light, resulting in a reduction of the contrast of light reflected from different directions.

[0020] In various embodiments, the controller is configured to perform the calibration procedure in response to a triggering event, said triggering event being any one or more of the illumination device is switched on, a calibration timer lapses, a specified point in time is reached, darkness is detected.

[0021] The calibration procedure may thus be performed at any suitable point in time, including more or less continuously by setting a calibration timer to a desirable repeating interval.

[0022] In various embodiments, the controller is configured to perform the calibration procedure by controlling the lighting units to emit a respective light beam during a respective time interval such that, at any given time interval, only one lighting unit emits a light beam. The sensor signals are analyzed to obtain received intensity values, each received intensity value being representative of an intensity of received light in respective light beam direction when each respective lighting unit is emitting a light beam. The sensor signals are also analyzed to obtain background intensity values, each background intensity value being representative of an intensity of received light in respective light beam direction when each respective lighting unit is not emitting a light beam. The reflection intensity values for each respective light beam direction are then obtained by subtracting respective background intensity value from respective received intensity value.

[0023] Such a calibration procedure reduces the illumination of directions where there is no object to be illuminated. In this way, light pollution is reduced, and the illumination device becomes more energy efficient. By analyzing the background intensity values, light originating from external light sources can be identified. Thus, a scenario where illumination 2024PF80142 4 from external light sources is interpreted as reflected light from the lighting units can be avoided.

[0024] In various embodiments, the controller is configured to perform the calibration procedure by controlling a plurality of the lighting units to emit a respective light beam, the emission being time modulated by a respective modulation pattern that is unique for each respective lighting unit. The sensor signals are analyzed to obtain received intensity values, each received intensity value being representative of an intensity of received light having a respective matching modulation pattern in respective light beam direction. The sensor signals are also analyzed to obtain background intensity values, each background intensity value being representative of an intensity of received light having a respective non-matching modulation pattern in respective light beam direction. The reflection intensity values for each respective light beam direction are then obtained by subtracting respective background intensity value from respective received intensity value.

[0025] Such a calibration procedure allows for simultaneous calibration of a plurality of lighting units, since light originating from specific lighting units can be distinguished based on their respective modulation pattern.

[0026] In various embodiments, the controller is configured to perform the calibration procedure by controlling a plurality of the lighting units to emit a respective light beam, having a respective color that is unique for each respective lighting unit. The sensor signals are analyzed to obtain received intensity values, each received intensity value being representative of an intensity of received light having a respective matching color in respective light beam direction. The sensor signals are also analyzed to obtain background intensity values, each background intensity value being representative of an intensity of received light having a respective non-matching color in respective light beam direction. The reflection intensity values for each respective light beam direction are then obtained by subtracting respective background intensity value from respective received intensity value.

[0027] Such a calibration procedure allows for simultaneous calibration of a plurality of lighting units, since light originating from specific lighting units can be distinguished based on their respective color.

[0028] In various embodiments, the controller is configured such that the analyzing of the sensor signals to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction, comprises determining, for each light beam direction, a respective overlap value between the light beam 2024PF80142 5 corresponding to the light beam direction and each sensor field of view. A determination is made, for each light beam direction, of the respective reflection intensity value by adding the sensor signals weighted by respective overlap value.

[0029] With such weighting of the sensor signals, it is possible to account for differences in the measured light level at each light sensor that originate from variations in location of a specific lighting unit relative each respective light sensor. In other words, it becomes possible to distinguish between a lighting unit having a light beam direction that overlaps with a respective sensor direction, and a lighting unit where the light beam direction is away from a respective sensor direction.

[0030] In a further aspect there is provided a method performed by a controller for controlling an illumination device, the illumination device comprising a plurality of lighting units, each lighting unit being configured to emit a respective light beam in a respective light beam direction, a plurality of light sensors, each light sensor being configured to sense light in a respective sensor field of view in a respective sensor direction. The method comprises the steps of receiving sensor signals from the light sensors, each sensor signal representing a light level in each respective sensor direction. The sensor signals are analyzed to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction. The lighting units are then controlled to emit a respective light beam such that, for each light beam direction, if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction is reduced.

[0031] In yet a further aspect there is provided a non-transitory computer-readable storage medium having stored thereon instructions for implementing the method as summarized above, when executed on a device having processing capabilities.

[0032] Such a method and such a non-transitory computer-readable storage medium and embodiments of such a method and such a non-transitory computer-readable storage medium provide corresponding effects and advantages as summarized above in connection with the illumination device.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. 2024PF80142 6

[0035] Figure la schematically illustrates an illumination device.

[0036] Figure lb schematically illustrates an outdoor scenario with an illumination device.

[0037] Figure 1c schematically illustrates a controller.

[0038] Figure 2 is a flowchart.

[0039] Figures 3a and 3b are flowcharts.

[0040] The schematic drawings are not necessarily to scale.

[0041] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] As exemplified in a schematical way in figures la and lb, an embodiment of a multibeam illumination device 1 is capable of shining light in different, individually controllable directions. Below these directions will be denoted light beam directions 23. As will be described in more detail below, the illumination device 1 is configured to sense the back-reflected light, preferably including background light, for each direction and respond to it. As indicated in an outdoor environment illustrated in figure la, the reflected light is light reflected by objects in the vicinity of the illumination device 1, for example a building 151 and trees 152. The sensing is done, by means of sensors 5 having field of views 15 in a respective sensor direction 25, in a calibration procedure that may be triggered and performed at any desired point or points in time, for example once a day / week / month, or when triggered or switched on by sensing a user action such as a button being pressed, or the calibration may be performed continuously repeated. As will be described in more detail below, the response to the sensing of back-reflected light, preferably including background light, may follow different scenarios:

[0043] Switch off or dim to a low level, for example less than 10 %, when the back reflection (feedback sensor signal) is below a threshold level (i.e. meaning that there is nothing nearby to illuminate in that direction) to avoid light pollution / trespass.

[0044] Enhance contrast: set dim level proportional to the feedback sensor signal (i.e. meaning that most light is concentrated on the object that reflects most light because it is either very close, very large, or white). Proportional is to be understood as dim level monotonically increasing for an increased feedback sensor signal. For example the relationship between dim level and feedback sensor signal may be linear, quadratic, or any other monotonic relationship. 2024PF80142 7

[0045] Reduce contrast: set dim level inversely proportional to feedback sensor signal or with a negative proportionality (i.e. meaning that light is redistributed such that the differences between back reflections from different directions are evened out, leading to more uniform illumination of the surrounding). Proportional is to be understood as dim level monotonically decreasing for an increased feedback sensor signal. For example the relationship between dim level and feedback sensor signal may be linear, quadratic, or any other monotonic relationship.

[0046] Combinations, for example in the form of a threshold in combination with positive or negative feedback sensor signal, or positive feedback in one range and negative in another range.

[0047] To improve the sensitivity of the illumination device 1 (i.e. distinguishing the feedback sensor signal from background), multiple sensors are used facing different directions. The sensor signal may then be weighed according to the alignment of the sensor orientation and the orientation of light beam directions that are being calibrated. Alternatively, sensitivity may be further enhanced by adding a specific time modulation to light beams during calibration and using this modulation as a filter for the sensor signal. Another approach involves use of a specific color of the light beam providing the calibration source and a corresponding color filter in front of the sensor that blocks light with different colors. Alternatively to using a color filter, the light sensor may measure the spectral response of the sensed light and use the result to weigh the sensor signal.

[0048] As illustrated in figures la and lb the illumination device 1 comprises a plurality of lighting units, each lighting unit 3 being configured to emit a respective light beam 13 in a respective light beam direction 23. A plurality of light sensors 5 are configured to sense light in a respective sensor field of view 15 in a respective sensor direction 25. A controller 7 is configured to perform a calibration procedure that comprises receiving sensor signals from the light sensors 5, each sensor signal representing a light level in each respective sensor direction 25. The sensor signals are analyzed to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction 23. The lighting units 3 are controlled to emit a respective light beam 13 such that, for each light beam direction 23, if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction 23 is reduced. For example, the threshold value may be preset by a user or preset during fabrication. 2024PF80142 8

[0049] Although preferred embodiments of the illumination device 1 comprises a plurality of lighting units 3 and a plurality of light sensors 5, alternative embodiments may be configured with one sensor with a wide sensor field of view that covers all light beam directions. In such embodiments, there should be at least two lighting units with different light beam directions. In another embodiment the illumination device 1 comprises one lighting unit 3 and one light sensor 5.

[0050] With reference to figure 1c and figure 2, a method performed by the controller 7 for controlling the illumination device 1 comprises the steps of receiving 201 sensor signals from the light sensors 5, each sensor signal representing a light level in each respective sensor direction 25. The sensor signals are analyzed 203 to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction 23. The lighting units 3 are then controlled 205 to emit a respective light beam 13 such that, for each light beam direction 23, if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction 23 is reduced. A non-transitory computer-readable storage medium 70 comprises stored instructions for implementing the method of figure 2, when executed on the illumination device 1 having a processor 71.

[0051] The controller 7 may be configured to control the lighting units 3 to emit a respective light beam 13 such that, for each light beam direction 23, if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction 23 is adjusted by a factor that is proportional to the reflection intensity value for the light beam direction 23. Alternatively, the controller 7 may be configured to control the lighting units 3 to emit a respective light beam 13 such that, for each light beam direction 23, if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction 23 is adjusted by a factor that is negatively proportional to the reflection intensity value for the light beam direction 23. Alternatively, the controller 7 may be configured to control the lighting units 3 to emit a respective light beam 13 such that, for each light beam direction 23, if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction 23 is adjusted by a factor that is inversely proportional to the reflection intensity value for the light beam direction 23.

[0052] The controller 7 may be configured to perform the calibration procedure in response to a triggering event, said triggering event being any one or more of: the illumination 2024PF80142 9 device 1 is switched on, a calibration timer lapses, a specified point in time is reached, background light intensity is below or above a background threshold value (for example, corresponding to sunrise and sunset).

[0053] The controller 7 may be configured to perform the calibration procedure by controlling the lighting units 3 to emit a respective light beam 13 during a respective time interval such that, at any given time interval, only one lighting unit 3 emits a light beam 13. In such embodiments, the sensor signals are analyzed to obtain received intensity values, each received intensity value being representative of an intensity of received light in respective light beam direction 23 when each respective lighting unit is emitting a light beam 13. The sensor signals are also analyzed to obtain background intensity values, each background intensity value being representative of an intensity of received light in respective light beam direction 23 when each respective lighting unit is not emitting a light beam 13. The reflection intensity values for each respective light beam direction 23 is then obtained by subtracting respective background intensity value from respective received intensity value. Such embodiments include an embodiment that will be described in more detail below in connection with figures 3a and 3b.

[0054] The controller 7 may be configured to perform the calibration procedure by controlling a plurality of the lighting units 3 to emit a respective light beam 13, the emission being time modulated by a respective modulation pattern that is unique for each respective lighting unit 3. In such embodiments, the sensor signals are analyzed to obtain received intensity values, each received intensity value being representative of an intensity of received light having a respective matching modulation pattern in respective light beam direction 23. In such embodiments, the sensor signals are also analyzed to obtain background intensity values, each background intensity value being representative of an intensity of received light having a respective non-matching modulation pattern in respective light beam direction 23. The reflection intensity values for each respective light beam direction 23 is then obtained by subtracting respective background intensity value from respective received intensity value.

[0055] For example, a first lighting unit 3 may be configured to flicker on and off at a first rate (modulation pattern), a second lighting unit 3 may be configured to flicker on and off at a second rate, and so on, the example may contain any number of lighting units 3 with a respective rate of flickering. A rate of flickering may for example be 100 Hz or 150 Hz. The light sensors 5 having an integration time sufficiently low to distinguish and separate different modulation patterns, for example below 1 ms. By analyzing the modulation pattern of 2024PF80142 10 received light, it can be determined whether one or several lighting units are turned on, and which one(s) of the lighting units is(are) turned on. Subsequently, it may be determined what is the intensity of received light originating from each respective lighting unit 3.

[0056] The controller 7 may be configured to perform the calibration procedure by controlling a plurality of the lighting units 3 to emit a respective light beam 13, having a respective color that is unique for each respective lighting unit 3. In such embodiments, the sensor signals are analyzed to obtain received intensity values, each received intensity value being representative of an intensity of received light having a respective matching color in respective light beam direction 23. In such embodiments, the sensor signals are also analyzed to obtain background intensity values, each background intensity value being representative of an intensity of received light having a respective non-matching color in respective light beam direction 23. The reflection intensity values for each respective light beam direction 23 is then obtained by subtracting respective background intensity value from respective received intensity value.

[0057] For example, a first lighting unit 3 may be configured to emit a light beam 13 with a first peak wavelength, a second lighting unit 3 may be configured to emit a light beam 13 with a second peak wavelength, and so on, the example may contain any number of lighting units 3 with a respective peak wavelength. In one embodiment, light sensors 5 with different known spectral sensitivity may be used to identify from which light sensor(s) the received light is originating. Alternatively, a sensor which can measure the whole spectrum can be used. Subsequently, it may be determined what is the intensity of received light originating from each respective lighting unit 3.

[0058] The controller 7 may be configured such that the analyzing of the sensor signals to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction 23, comprises determining, for each light beam direction 23, a respective overlap value between the light beam 13 corresponding to the light beam direction 23 and each sensor field of view 15. A determination is then made, for each light beam direction 23, of the respective reflection intensity value by adding the sensor signals weighted by respective overlap value. Such embodiments include an embodiment illustrated by flowcharts in figures 3a and 3b. That is, figures 3a and 3b illustrate a flowchart of an embodiment of a method performed by the controller 7 for controlling the illumination device 1 illustrated in figures la and lb, using a 2024PF80142 11 scheme wherein the sensor signals are weighted according to the angular relationships between the sensor directions 25 and the light beam directions 23.

[0059] As illustrated in figure la, twelve light sources 3 are equally spread around the pole at every 30 degrees angle and three light sensors 5 measuring the background and reflecting light are also equally oriented at every 120 degrees angle.

[0060] In the method, during steps 301-311, each sensor 5 m first measures the background light (denoted bg[m], where m equals 0, 1, 2 in this embodiment) when all light sources 3 are off.

[0061] Then, in steps 313-329 each light source i is lit up sequentially and individually. According to steps 313-329, every time a light source 3 is on, each sensor 5 measures the current light condition (denoted lux[i, m], where i equals 0, 1, . . ., 11 in this embodiment).

[0062] According to steps 331-351, the angle of the sensor m with respect to the emitting light source i is considered using a weight factor, such that:

[0063] Here, as illustrated in step 335, Weighty, m) is the weight factor, i is the light source number (0, . . ., 11) and m is the sensor number (0, . . ., 2). Of course, the number of light sources and sensor numbers are not limited to the numbers exemplified in the embodiment described here.

[0064] In some embodiments, the directionality of the weights can be influenced by introducing a k value:

[0065] . k

[0066] Ti (i 1\

[0067] Weight(i, m) cos — - — 2m — - + 1!

[0068] [3 \2 4 J

[0069] Using the same weights, the background intensity is subtracted from the measurement in step 341 to result in a single intensity value per light source 3. If this resulting intensity value exceeds a threshold (z.e., the measured flux is notably higher when the light source 3 is on), that light source 3 is turned on in step 345 and, correspondingly, if this resulting intensity value does not exceed the threshold (z.e., the measured flux is notably 2024PF80142 12 lower when the light source 3 is on), that light source 3 is reduced in intensity, in step 347 illustrated as being turned off.

Claims

2024PF80142 13CLAIMS:

1. An illumination device (1) comprising: a plurality of lighting units (3), each lighting unit (3) being configured to emit a respective light beam (13) in a respective light beam direction (23), a plurality of light sensors (5), each light sensor (5) being configured to sense light in a respective sensor field of view (15) in a respective sensor direction (25), and a controller (7) configured to perform a calibration procedure, wherein the calibration procedure comprises: receiving sensor signals from the light sensors (5), each sensor signal representing a light level in each respective sensor direction (25), analyzing the sensor signals to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction (23), and controlling the lighting units (3) to emit a respective light beam (13) such that, for each light beam direction (23), if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction (23) is reduced.

2. The illumination device (1) according to claim 1, wherein the controller (7) is configured to: control the lighting units (3) to emit a respective light beam (13) such that, for each light beam direction (23), if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction (23) is adjusted by a factor that is proportional to the reflection intensity value for the light beam direction (23).

3. The illumination device (1) according to claim 1, wherein the controller (7) is configured to: control the lighting units (3) to emit a respective light beam (13) such that, for each light beam direction (23), if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction (23) is adjusted by a2024PF80142 14 factor that is negatively proportional to the reflection intensity value for the light beam direction (23).

4. The illumination device (1) according to claim 1, wherein the controller (7) is configured to: control the lighting units (3) to emit a respective light beam (13) such that, for each light beam direction (23), if the reflection intensity value is greater than the reflection threshold value, the intensity of emitted light in the light beam direction (23) is adjusted by a factor that is inversely proportional to the reflection intensity value for the light beam direction (23).

5. The illumination device (1) according to any one of claims 1 to 4, wherein the controller (7) is configured to perform the calibration procedure in response to a triggering event, and wherein the triggering event is any one or more of: the illumination device (1) is switched on, a calibration timer lapses, a specified point in time is reached, and background light intensity is below or above a background threshold value.

6. The illumination device (1) according to any one of claims 1 to 5, wherein the controller (7) is configured to perform the calibration procedure by: controlling the lighting units (3) to emit a respective light beam (13) during a respective time interval such that, at any given time interval, only one lighting unit (3) emits a light beam (13), analyzing the sensor signals to obtain received intensity values, each received intensity value being representative of an intensity of received light in respective light beam direction (23) when each respective lighting unit is emitting a light beam (13), analyzing the sensor signals to obtain background intensity values, each background intensity value being representative of an intensity of received light in respective light beam direction (23) when each respective lighting unit is not emitting a light beam (13), and2024PF80142 15 obtaining the reflection intensity values for each respective light beam direction (23) by subtracting respective background intensity value from respective received intensity value.

7. The illumination device (1) according to any one of claims 1 to 5, wherein the controller (7) is configured to perform the calibration procedure by: controlling a plurality of the lighting units (3) to emit a respective light beam (13), the emission being time modulated by a respective modulation pattern that is unique for each respective lighting unit (3), analyzing the sensor signals to obtain received intensity values, each received intensity value being representative of an intensity of received light having a respective matching modulation pattern in respective light beam direction (23), analyzing the sensor signals to obtain background intensity values, each background intensity value being representative of an intensity of received light having a respective non-matching modulation pattern in respective light beam direction (23), and obtaining the reflection intensity values for each respective light beam direction (23) by subtracting respective background intensity value from respective received intensity value.

8. The illumination device (1) according to any one of claims 1 to 5, or according to claim 7, wherein the controller (7) is configured to perform the calibration procedure by: controlling a plurality of the lighting units (3) to emit a respective light beam (13), having a respective color that is unique for each respective lighting unit (3), analyzing the sensor signals to obtain received intensity values, each received intensity value being representative of an intensity of received light having a respective matching color in respective light beam direction (23), analyzing the sensor signals to obtain background intensity values, each background intensity value being representative of an intensity of received light having a respective non-matching color in respective light beam direction (23), and obtaining the reflection intensity values for each respective light beam direction (23) by subtracting respective background intensity value from respective received intensity value.2024PF80142 169. The illumination device (1) according to any one of claims 1 to 8, wherein the controller (7) is configured such that the analyzing of the sensor signals to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction (23), comprises: determining, for each light beam direction (23), a respective overlap value between the light beam (13) corresponding to the light beam direction (23) and each sensor field of view (15), and determining, for each light beam direction (23), the respective reflection intensity value by adding the sensor signals weighted by respective overlap value.

10. A method performed by a controller (7) for controlling an illumination device (1), the illumination device (1) comprising: a plurality of lighting units (3), each lighting unit (3) being configured to emit a respective light beam (13) in a respective light beam direction (23), a plurality of light sensors (5), each light sensor (5) being configured to sense light in a respective sensor field of view (15) in a respective sensor direction (25), wherein the method comprising the steps of : receiving (201) sensor signals from the light sensors (5), each sensor signal representing a light level in each respective sensor direction (25), analyzing (203) the sensor signals to obtain reflection intensity values, each reflection intensity value being representative of an intensity of reflected light in a respective light beam direction (23), and controlling (205) the lighting units (3) to emit a respective light beam (13) such that, for each light beam direction (23), if the reflection intensity value is less than or equal to a reflection threshold value, the intensity of emitted light in the light beam direction (23) is reduced.

11. A non-transitory computer-readable storage medium (70) having stored thereon instructions for implementing the method according to claim 10, when executed on an illumination device (1) having a processor (71).

Images