System and method for dimming a lighting device

Abstract

Lighting systems and methods for controlling lighting systems are disclosed. The system comprises a first white light source for emitting first white light with a first correlated color temperature, a green light source for emitting green light, and a controller for individually controlling the first white light source and the green light source. The controller is configured to receive a signal representing a target luminous flux; to determine, in response to receiving the signal representing a target luminous flux, based on the target luminous flux, a first luminous flux for the first white light source and a second luminous flux for the green light source; and to control the first white light source to emit the first white light with the first luminous flux and to control the green light source to emit the green light with the second luminous flux. Herein, in a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with the target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value.

Description

[0001] 2024PF80154 1

[0002] SYSTEM AND METHOD FOR DIMMING A LIGHTING DEVICE

[0003] FIELD OF THE INVENTION

[0004] This disclosure relates to a system and method for dimming a lighting device, in particular to such system wherein the lighting device is dimmed towards a green point. This disclosure further relates to a computer-implemented method for dimming a lighting device and to a computer program and computer-readable storage medium for performing such method.

[0005] BACKGROUND OF THE INVENTION

[0006] Current lighting systems emitting white light often exhibit a so-called “dim-to- warm” behavior, which means that the correlated color temperature of the emitted light decreases with the intensity (measured as, e.g., luminous flux) of the emitted light decreases. White light with a lower correlated color temperature is generally perceived as ‘warmer’ (due to having a reddish chromaticity) than white light with a higher correlated color temperature, which is generally perceived as ‘cooler’ (due to having a bluish chromaticity).

[0007] US 2008 / 0103561 Al discloses apparatus and methods for treating psychiatric disorders, mood disorders and circadian rhythm disorders with a multi-stage light protocol. Typically, the light includes white light having a broad spectrum. In some embodiments, the light further includes light having a medium wavelength, for example, wavelengths between 520 nm and 535 nm.

[0008] Persons suffering from neurological disorders such as migraine may have an increased sensitivity to light. Consequently, when they are suffering from an attack, or about to suffer from an attack, they may reduce the light intensity in their environment. As noted, this may result in the chromaticity of the emitted light moving towards the red end of the color space. However, it has been found that being exposed to more reddish light may increase the suffering of the aforementioned persons, which may cause them to further reduce the intensity of the light, which negatively affects visibility due to (very) low light levels.

[0009] In light of the above, there is a need in the art for a system and method for emitting light that balances visibility with comfort. 2024PF80154 2

[0010] SUMMARY OF THE INVENTION

[0011] To that end, a lighting system is disclosed.

[0012] The lighting system comprises a first white light source for emitting first white light with a first correlated color temperature, a green light source for emitting green light, and a controller for individually controlling the first white light source and the green light source. The controller is configured to receive a signal representing a target luminous flux; to determine, in response to receiving the signal representing a target luminous flux, based on the target luminous flux, a first luminous flux for the first white light source and a second luminous flux for the green light source; and to control the first white light source to emit the first white light with the first luminous flux and to control the green light source to emit the green light with the second luminous flux. Herein, in a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with decreasing target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value.

[0013] By ensuring that the first (white) luminous flux decreases relative to the second (green) luminous flux as the total luminous flux decreases, the light becomes more greenish as the light intensity becomes smaller. In other words, a dimming profile is achieved wherein the emitted light becomes more greenish and less white, as the emitted light becomes more dim. This may also be referred to as “dim-to-green” behavior. As low-intensity green light is known to be beneficial (at least relative to light with different colors at the same intensity) for persons suffering from certain neurological disorders, such as migraine, such dim-to-green behavior can reduce complaints from such persons. Moreover, green light has improved legibility compared to, e.g., white light, especially at low light levels, so that with equal intensity, green light may better facilitate reading and similar activities.

[0014] It has been found that animals suffering from stress may have an increased sensitivity to light. The present invention may theefore also be advantageous to reduce stress in such animals. Animals may for example be livestock. Hence, the lighting systems and computer implemented methods disclosed herein can mutatis mutandis also be applied to an animal and be used to reduce stress in the animal.

[0015] In general, the target luminous flux may be provided, e.g., as an absolute luminous flux in lumen, as a relative light intensity, e.g., on a scale of 0-100 %, or in any other suitable format. The target luminous flux may also be provided indirectly, e.g., by specifying an absolute or relative radiant flux, which can be converted to a luminous flux. 2024PF80154 3

[0016] The lighting system may comprise one or more lighting devices, each lighting device of the one or more lighting devices comprising one or more of the light sources. The controller may be integrated in a lighting device, or be embodied in a separate device. For example, the lighting system may comprise one or more substantially identical lighting devices, each lighting device of the one or more substantially identical lighting devices comprising a first white light source and a green light source, and a central controller communicatively connected to each of the one or more lighting devices. In some embodiments, at least part of the functionality of the controller may be implemented on a mobile device, or on a smart home device.

[0017] The controller may comprise a processor, e.g., a microprocessor, and a memory, communicatively connected to the processor, storing instructions that, when executed, configure the processor to execute the method steps as described herein. The memory may further store the first and second target luminous flux values. The controller may further comprise a communication interface, communicatively connected to the processor for receiving the signal representing the target luminous flux. Additionally or alternatively, the controller may comprise or be communicatively connected to a user interface which may be configured for generating the signal representing the target luminous flux.

[0018] In other embodiments, the controller may be implemented as an electronic circuit.

[0019] In an embodiment, the green light source is a direct green solid-state light source. In an embodiment, the green light source is a phosphor-converted solid-state light source. As used herein, a solid-state light source may include, e.g., a LED light source, a solid-state laser and / or a semiconductor laser. Similarly, the white light source may be a (phosphor-converted) solid-state light source, such as a LED light source.

[0020] Such solid-state light sources may have relatively narrow spectral bands, e.g., with a FWHM of less than 70 nm, less than 50 nm, less than 30 nm, less than 20 nm, or even less than 10 nm. This in turn can ensure a maximal reduction of light-related symptoms in person suffering from neurological disorders.

[0021] Phosphor-converted solid-state light sources may have relatively narrow or broad spectral bands depending on the properties of the phosphor-conversion material used.

[0022] In an embodiment, the lighting system further comprises a second white light source for emitting second white light with a second correlated color temperature. The second correlated color temperature may be higher than the first correlated color temperature. The 2024PF80I54 4 controller may be further configured to determine, based on the target luminous flux, a third luminous flux for the second white light source, and to control the second white light source to emit the second white light with the third luminous flux.

[0023] In an embodiment, in a second operational mode, a ratio between the third luminous flux and the first luminous flux decreases with decreasing target luminous flux in the interval between the first target luminous flux value and the second target luminous flux value. This way, a user can switch between dim-to-green and dim-to-warm.

[0024] In an embodiment, a ratio between the third luminous flux and the first luminous flux decreases with decreasing target luminous flux in an interval between a third target luminous flux value, higher than the first target luminous flux value, and the first target luminous flux value.

[0025] This way, the lighting system may (when following a dimming profile form bright to dim), first perform dim-to-warm behavior, and subsequently dim-to-green behavior. To that end, the memory may store the third target luminous flux value in addition to the first and second target luminous flux values. It is noted that if the initial correlated color temperature (i.e., the correlated color temperature at a high, e.g., maximum, luminous flux value) is sufficiently high, dim-to-warm and dim-to-green may (partially) coincide; i.e., in such cases, light with a lower CCT may also have a larger green component, down to a certain CCT. Consequently, by dimming to a CCT that is neither bluish (high CCT) nor reddish (low CCT), discomfort of a user may be reduced, even while the emitted light is still white. Conversely, if the initial CCT is relatively low (e.g., so that the white light is already reddish), dim-to-warm may be avoided as it may increase the discomfort of the user.

[0026] It is noted that either of the options of using dim-to-warm as an alternative to dim-to-green or as a precursor to dim-to-green may be present, as well as a combination of them.

[0027] In an embodiment, the controller is further configured to selectively activate the first operational mode based on at least one of: a time of the day and / or a day of the week, a signal from a switch provided on a device of the lighting system, reception of an external switch signal via a communication interface of the lighting system, detection of a speech command by the lighting system, or behavioral and / or physiological analysis, by the lighting system, of a user. This way, the lighting system can react (or proact) to reduce discomfort of the user.

[0028] The device on which the switch is provided can be a lighting device or a controller device. The lighting system may comprise one or more sensors, e.g., a sound and / or 2024PF80154 5 image sensor. These sensors may be integrated in a lighting device or in a controller device, e.g., a smart light controller or a smart home controller. The lighting system may furthermore comprise a processor and a memory, communicatively coupled to the processor, storing sound and / or image recognition software, e.g., a trained Al model. Software for recognizing spoken or gestured commands are well-known in the art.

[0029] In an embodiment, the behavioral and / or physiological analysis results in a signal indicative of a neurological disorder situation, an onset of the neurological disorder or an expected / predicted onset of the neurological disorder. For example, based on a comparison of actual data on behavior and / or physiological condition of a user with historical data on behavior and / or physiological condition of that user and occurrences of the neurological disorder at that user, artificial intelligence systems can be used to learn when the onset of the neurological disorder may be expected based on actual data on behavior and / or physiological condition on a user. An example of such a system is described by P. Siirtola et al., in ‘Using sleep time data from wearable sensors for early detection of migraine attacks’, Sensors 2018, 18, 1374; doi: 10.3390 / sl8051374, which is hereby incorporated by reference in its entirety. The neurological disorder may comprise at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0030] In an embodiment, the controller is further configured to define or update first target luminous flux value and / or the second target luminous flux value in response to a signal received from a user interface. This allows a user to define the dimming behavior based on personal preferences.

[0031] In an embodiment, in the first operational mode, for any intermediate target luminous flux value in the interval between the first target luminous flux value and the second target luminous flux value, a relative second luminous flux is equal to or larger than a linear interpolation of the relative second luminous flux at the first target luminous flux value and the relative second luminous flux at the second target luminous flux value, wherein the relative second luminous flux is defined as a ratio of the second luminous flux and a sum of the first luminous flux and the second luminous flux.

[0032] Such behavior may also be referred to as linear (for “equal to”) or super-linear (for “larger than”) behavior. By increasing the relative contribution of the green light relatively fast, the discomfort-reducing effects are obtained already by moderate dimming, so that normal activity is minimally disrupted.

[0033] In an embodiment, the green light has a peak wavelength between 480 nm and 590 nm, between 490 nm and 560 nm, or between 500 nm and 540 nm. In particular, the peak 2024PF80154 6 wavelength can be between 495 nm and 570 nm, or between 520 nm and 560 nm.

[0034] Additionally or alternatively, the green light may have a chromaticity in an area defined by (x, y) coordinates (0.30, 0.42), (0.5, 0.5) and (0.237, 0.748) according to the CIE 1931 x,y chromaticity space. This area comprises slightly yellowish greens, which have been found to be perceived as relatively comfortable.

[0035] In an embodiment, the second target luminous flux value is at most 75 %, at most 50 %, or at most 25 % of the first target luminous flux value. In an embodiment, the controller may be configured to receive a signal indicative of the actual (or current) luminous flux (i.e., the actual luminous output value) of the lighting system and determine the first target luminous flux value and / or the third target luminous flux value, based on the actual luminous flux, for example equal to, such that the dimming curve, whether dim-to-green according to claim 1 or dim-to-warm according to claims 3 or 4 starts at the actual luminous flux value.

[0036] In a further aspect, embodiments of this disclosure relate to a computer- implemented method for controlling a lighting device. The lighting device comprises a first white light source for emitting first white light with a first correlated color temperature and a green light source for emitting green light. The method comprises: receiving a signal representing a target luminous flux, in response to receiving the signal representing the target luminous flux, determining, based on the target luminous flux, a first luminous flux for the first white light source and a second luminous flux for the green light source, and controlling the first white light source to emit the first white light with the first luminous flux and controlling the green light source to emit the green light with the second luminous flux. In a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with decreasing target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value.

[0037] In an embodiment, in the first operational mode, for any intermediate target luminous flux value in the interval between the first target luminous flux value and the second target luminous flux value, a relative second luminous flux is equal to or larger than a linear interpolation of the relative second luminous flux at the first target luminous flux value and the relative second luminous flux at the second target luminous flux value, wherein the relative second luminous flux is defined as a ratio of the second luminous flux and a sum of the first luminous flux and the second luminous flux. 2024PF80154 7

[0038] Thus, a system as described above may be controlled using one of the methods described herein. The method may be executed, for example, by the controller described above.

[0039] One aspect of this disclosure relates to a computer comprising a computer readable storage medium having computer readable program code embodied therewith, and a processor, preferably a microprocessor, coupled to the computer readable storage medium, wherein responsive to executing the computer readable program code, the processor is configured to perform any of the methods disclosed herein.

[0040] A further aspect of this disclosure relates to a computer program comprising instructions which, when executed by a controller of a lighting system as described above, causes the data processing system thereof to perform the method as describes above. Such a computer program may be included in an application (e.g., downloadable from an app store) and adapted to, when downloaded, stored and opened on a portable (personal) computing device such as a smartphone or tablet, allow the smartphone or tablet to control the lighting system as described above according to the method as described above. An example of such application is the Philips Hue app, available from the applicant. Also disclosed herein is a computer readable signal medium for transmitting such computer program or a non-transitory computer-readable storage medium having stored thereon such computer program.

[0041] One aspect of this disclosure relates to a computer program or suite of computer programs comprising at least one software code portion or a computer program product storing at least one software code portion, the software code portion, when run on a computer system, being configured for executing any of the methods disclosed herein.

[0042] One aspect of this disclosure relates to a non-transitory computer-readable storage medium storing at least one software code portion, the software code portion, when executed or processed by a computer, is configured to perform any of the methods disclosed herein.

[0043] As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, a method or a computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Functions described in this disclosure may be implemented as an algorithm executed by a processor / microprocessor of a computer. Furthermore, aspects of the present invention may take the form of a computer program 2024PF80154 8 product embodied in one or more computer readable medium(s) having computer readable program code embodied, e.g., stored, thereon.

[0044] Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer readable storage medium may include, but are not limited to, the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of the present invention, a computer readable storage medium may be any tangible medium that can contain, or store, a program for use by or in connection with an instruction execution system, apparatus, or device.

[0045] A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0046] Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber, cable, RF, etc., or any suitable combination of the foregoing. Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java™, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user’ s computer, partly on the user’ s computer, as a stand-alone software package, partly on the user’s computer and partly on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user’s computer through any type of network, including a local area 2024PF80154 9 network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0047] Aspects of the present invention are described below with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products as claimed in embodiments of the present invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor, in particular a microprocessor or a central processing unit (CPU), of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer, other programmable data processing apparatus, or other devices create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0048] These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0049] The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0050] The flowchart and diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products as claimed in various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality 2024PF80154 10 involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0051] Moreover, a computer program for carrying out the methods described herein, as well as a non-transitory computer readable storage-medium storing the computer program are provided. A computer program may, for example, be downloaded (updated) to the existing systems (e.g., to the existing control systems) or be stored upon manufacturing of these systems.

[0052] Elements and aspects discussed for or in relation with a particular embodiment may be suitably combined with elements and aspects of other embodiments, unless explicitly stated otherwise. Embodiments of the present invention will be further illustrated with reference to the attached drawings, which schematically will show embodiments as claimed in the invention. It will be understood that the present invention is not in any way restricted to these specific embodiments.

[0053] BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Aspects of the invention will be explained in greater detail by reference to exemplary embodiments shown in the drawings, in which:

[0055] FIG. 1 A-1C schematically depict lighting systems according to various embodiments;

[0056] FIG. 2A-2D schematically depict a dimming behavior according to an embodiment;

[0057] FIG. 3 A-3D schematically depict a dimming behavior according to an embodiment;

[0058] FIG. 4A-4D schematically depict a dimming behavior according to an embodiment;

[0059] FIG. 5A and 5B are flowcharts of methods according to various embodiments;

[0060] FIG. 6 is a flowchart of a method according to an embodiment;

[0061] FIG. 7A is a graph of the CIE 1931 x,y chromaticity space and

[0062] FIG. 7B is a graph showing results of a perception test comparing light sources with various chromaticities; and

[0063] FIG. 8 illustrates a data processing system according to an embodiment. 2024PF80154 11

[0064] DETAILED DESCRIPTION OF THE DRAWINGS

[0065] In the figures, identical reference numbers indicate identical or similar elements.

[0066] FIG. 1A-1C schematically depict lighting systems according to various embodiments. A lighting system typically comprises one or more lighting devices and at least one controller to control the one or more lighting devices. The controller may be integrated in one (or more) of the lighting devices. The controller can also be external to the one or more lighting devices, for instance as a dedicated controller device or as an app on a mobile device. Various embodiments of such lighting systems are well known in the art.

[0067] In the embodiment shown in FIG. 1 A, the lighting system is embodied as a lighting device 2. In some embodiments, the lighting system may comprise several such lighting devices. The lighting device 2 comprises a green light source 3 for emitting green light and a white light source 4 for emitting white light. The green light source 3 can be, for example a direct green solid-state light source such as a LED light source, a solid-state laser or a semiconductor laser. Alternatively, the green light source can be a phosphor-converted solid-state light source. The green light may have a peak wavelength between 480 nm and 590 nm, e.g., between 490 nm and 560 nm, or between 500 nm and 540 nm. Similarly, the white light source 4 may be a solid-state light source, such as a LED light source. The white light source may have a correlated color temperature between 1700-6500 K, e.g., between 2200- 6500 K. Although only a single white light source and a single green light source is shown, the lighting device 2 may comprise several identical or different white light sources and / or green light sources.

[0068] The lighting system further comprises a controller 6 for individually controlling the green light source 3 and the white light source 4. In the depicted embodiment, the controller 6 is included in the lighting device 2. The controller 6 is configured to receive a signal representing a target luminous flux, for example from an (optional) interface 8, which may be a communication interface for communicating with a further device or a user interface for receiving input directly from a user. In some embodiments, the interface 8 may be integrated in the controller 6. The target luminous flux may be provided, e.g., as an absolute luminous flux in lumen, as a relative light intensity, e.g., on a scale of 0-100 %, or in any other suitable format. The target luminous flux may also be provided indirectly, e.g., by specifying an absolute or relative radiant flux.

[0069] The controller 6 is further configured to determine, in response to receiving the signal representing the target luminous flux, a first luminous flux for the white light source 4 2024PF80154 12 and a second luminous flux for the green light source 3. The first and second luminous fluxes are determined based on the target luminous flux. In general, the sum of all partial luminous fluxes may be equal to the target luminous flux. The controller 6 is configured to control the white light source 4 to emit the white light with the first luminous flux and to control the green light source 3 to emit the green light with the second luminous flux.

[0070] In a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with decreasing target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value. Some exemplary relations between the target luminous flux and the partial luminous fluxes are shown in Fig. 2-4.

[0071] The controller 6 may activate or deactivate the first operation mode in response to a signal received from the interface 8. The interface 8 may send the signal to the controller 6 in response to receiving a signal from a further device. The signal from the further device may be indicative of the onset or presence or expected / predicted onset of a neurological disorder, such as migraine, fibromyalgia, neuropathy, or chronic headaches. Additionally or alternatively, the controller 6 may activate or deactivate the first operation mode in response to a signal received from a (physical) switch provided on the lighting device 2. A physical switch allows easy activation or deactivation of the first operation mode.

[0072] Additionally or alternatively, the controller 6 may activate or deactivate the first operation mode based on analysis of sensor data, e.g., based on detection of a speech command and / or based on behavioral and / or physiological analysis of a user and / or based on presence or absence of a user which sensor data may further include user identification data (e.g., RFID). These options will be described in more detail with respect to Fig. 1C.

[0073] Additionally or alternatively, the controller 6 may activate or deactivate the first operation mode without any (direct) external input, e.g., based on criteria stored in a memory of the controller 6, e.g., based on a time of the day and / or a day of the week, or based on the scheduled presence or absence of a person. Certain neurological disorders are known to be strongly correlated to, e.g., time of the day, such as morning migraine which is associated with (early) mornings.

[0074] One or more control parameters for the light sources 3,4 corresponding to the first operation mode may be stored in a memory of the controller 6.

[0075] In general, the lighting device 2 may switch between the first operation mode and a second operation mode based on a behavioral and / or physiological analysis performed either by a component of the lighting device 2 or by an external device. Such behavioral 2024PF80154 13 and / or physiological analysis may result in a signal indicative of a neurological disorder situation, an onset of the neurological disorder or an expected / predicted onset of the neurological disorder, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0076] The green light may be light that is suitable for green-light therapy. Green-light therapy has been found to have a positive effect on pain reduction. Several studies have shown that exposure to green light can reduce chronic pain, including neuropathic pain and fibromyalgia. It is believed that green-light therapy works by modulating the activity of the pain receptors in the body, reducing inflammation and promoting tissue regeneration. This therapy is non-invasive and drug-free, making it a safe alternative for those who cannot tolerate or prefer to avoid medication. Additionally, green-light therapy has been shown to have a calming effect on the nervous system, which can help reduce stress and anxiety, further contributing to pain reduction. Overall, green-light therapy shows promising potential as a complementary therapy for pain management, and various green light therapy devices are known in the art.

[0077] FIG. IB depicts a lighting device 2 similar to the lighting device 2 described above with reference to Fig. 1 A, further comprising a further white light source, such that the lighting device 2 comprises a first white light source 4 and a second white light source 5. The first white light source 4 may be adapted for emitting first white light with a first correlated color temperature and the second white light source 5 may be adapted for emitting second white light with a second correlated color temperature. The second correlated color temperature may be higher than the first correlated color temperature. The second correlated color temperature may be in the interval 1700-6500 K. The difference between the first and second correlated color temperatures may be at least 500 K.

[0078] In such an embodiment, the controller 6 may be further configured to determine, based on the target luminous flux, a third luminous flux for the second white light source 5, and to control the second white light source 5 to emit the second white light with the third luminous flux. Herein, a ratio between the third luminous flux and the first luminous flux decreases with decreasing target luminous flux in an interval between a third target luminous flux value, higher than the first target luminous flux value, and the first target luminous flux value.

[0079] This way, the lighting system may (when following a dimming profile form bright to dim), first perform dim-to-warm behavior, and subsequently dim-to-green behavior. To that end, the memory may store the third luminous flux value in addition to the first and 2024PF80154 14 second target luminous flux values. It is noted that if the initial correlated color temperature (i.e., the correlated color temperature at a high, e.g., maximum, luminous flux value) is sufficiently high, dim-to-warm and dim-to-green may (partially) coincide. This is illustrated, e.g., in Fig. 4.

[0080] FIG. 1C schematically illustrates a lighting system according to a further embodiment. The system comprises one or more lighting devices 2 (e.g., as described above with reference to Fig. 1 A or IB) of which only a single one is shown in the drawing, and a system controller 10. The system controller 10 may be integrated in the lighting device 2 (e.g., as controller 6), or can be an external device, e.g., a server or a smartphone or other mobile device with a specific app.

[0081] An example of the system controller 10, embodied as controller 6 in a lighting device 2, has been described above with reference to Fig. 1 A and IB. Fig. 1C shows an example of a distributed controller with some controller functionality in controller 6 of the lighting device 2 and other controller functionality in system controller 10. The system controller 10 may comprise a memory storing user preferences defined by the user 1. The user preferences may comprise parameters defining the dim-to-green behavior. The user preferences may also define criteria for enabling the first operational mode, causing the lighting system to exhibit the dim-to-green behavior.

[0082] The controller may be configured for behavioral and / or physiological analysis of a user 1. Aspects of this disclosure are related to the controller 6, the lighting device 2, and the system comprising the lighting device 2 and the system controller 10 and, optionally, sensor device 19. Computer-implemented algorithms for behavioral and / or physiological analysis of a user, e.g., using sensor data from a sound sensor and / or an image sensor, are known in the art. An example of such an algorithm is described by Siirtola et al.

[0083] The lighting system may comprise a clock, allowing the lighting system to select a spectral power distribution, i.e., a particular combination of luminous fluxes of the white light(s) and the green light, from a plurality of spectral power distributions based a time of the day and / or a day of the week. It is known that certain disorders, such as migraine, are strongly correlated with time of the day, e.g., so-called morning migraine. Thus, the system may be configured to exhibit the dim-to-green behavior in the (early) morning, e.g., similar to a wake-up light. In some embodiments, the lighting device may change to a different dimming behavior, e.g., dim-to-warm later during the day, either gradually or abruptly. This may also be linked to an increase in luminous flux. 2024PF80154 15

[0084] The lighting system may comprise a physical switch (e.g., a so-called panic switch), allowing the user 1 to switch to and from the dim-to-green operation mode with a single push of a button. Such a switch may also have additional functionality, e.g., cycling though various operational modes, possibly comprising several dimming behaviors. The physical ‘panic’ switch may be integrated in the means for setting the target luminous flux, e.g., integrated in a dimmer rotary dial or a dimmer up / down switch, or may be a separate switch from the means for setting the target luminous flux.

[0085] In particular, an aspect of this disclosure relates to a controller 6 configured to switch a lighting device 2 between a first mode of operation wherein a first light with a first spectral power distribution is emitted and a second mode of operation wherein a second light with a second spectral power distribution is emitted, the controller 6 being configured to switch between the first mode of operation and the second mode of operation based on a signal representative of a behavioral and / or physiological condition of a user 1, wherein the behavioral or physiological condition is indicative of a neurological disorder situation, an onset of the neurological disorder, or an expected / predicted onset of the neurological disorder. Typical examples of neurological disorders comprise at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches. For example, the controller may switch between dim-to- warm behavior and dim-to-green behavior, whilst maintaining or dimming to the target luminous flux. As the corresponding dimming curves are different, this typically results in a change of the spectral power distribution at the target luminous flux. The controller may then configure the lighting system to emit light according to the selected dimming curve, when the target luminous flux is subsequently changed.

[0086] In some embodiments, the controller 10 and the controller 6 may be integrated in a single data processing device, e.g., as described below with reference to Fig. 8. In some embodiments, the sensor device 19 can be integrated into the lighting device 2.

[0087] The sensor device 19 can be or comprise a microphone to enable sound analysis, more in particular speech analysis. This may be used to detect speech commands, but also (or instead) to detect changes in speech patterns, such as slurring or a change in tempo, amplitude, frequency, et cetera, which may be indicative of the presence or onset or expected / predicted onset of a neurological disorder.

[0088] The sensor device 19 can be or comprise a camera to enable, e.g., image analysis to detect gestures (which may be interpreted as non-verbal commands), but also (or instead) to detect facial expressions and / or posture, or for emotion recognition (such as pain 2024PF80154 16 or tiredness), et cetera, which may be indicative of the presence or onset or expected / predicted of a neurological disorder.

[0089] The sensor device 19 can be or comprise a wearable device, such as a smart watch, fitness tracker, or medical monitoring device, e.g., configured to monitor one or more vital signs of the user 1 such as pulse, breathing patterns, heart rate variability, skin conductivity, temperature, sleep data, et cetera. Based on the output of the wearable device, e.g., based on one or more of the vital signs, a signal indicative of the presence or onset or expected / predicted of a neurological disorder may be determined.

[0090] The sensor device 19 can be or comprise an input device of a data processing system, such as a keyboard, mouse, or touchscreen. Parameters like typing speed, typing accuracy, and / or mouse movements may serve as an indicator of the presence or onset or expected / predicted of a neurological disorder.

[0091] For example, the user 1 can switch between regular dimming behavior and dim-to-green behavior, for example using a physical switch, a voice command, a gesture command, et cetera.

[0092] In a further example, an additional sensor (e.g. a camera 19) may detect / recognize the onset or expected / predicted or presence of a migraine attack or other light-sensitive neurological disorder of the user 1, and cause the controller 6 of the lighting device 2 to pro-actively change the light setting to the dim-to-green (and possibly reduced luminous flux).

[0093] The system controller may be configured to determine a number of users, e.g., based on input received from sensor device 19 (e.g., identifying different voices in an audio stream, or identifying persons in video data). The lighting system may be configured to enable or disable the first operational mode based on the number of users that is detected.

[0094] In a further aspect, embodiments in this disclosure are related to the controller 6,10 for a lighting device, e.g., for the lighting device 2 as described with reference to Fig. 1A-1C.

[0095] The controller 6,10 may be embodied as a data processing system as described below with reference to Fig. 8. For example, the controller 6,10 may comprise a processor, e.g., a microprocessor, and a memory, communicatively connected to the processor, storing instructions that, when executed, configure the processor to execute the method steps as described herein. The memory may further store the first and second target luminous flux values, and where relevant, the third and possibly further luminous flux values. The controller 6,10 may further comprise a communication interface, communicatively connected to the 2024PF80154 17 processor for receiving signals such as the signal representing the target luminous flux or any other signals as described above for controlling operation of the lighting device 2 (e.g., change operational mode, receive sensor data or receive user preferences). Additionally or alternatively, the controller 6,10 may comprise or be communicatively connected to a user interface which may be configured for generating signals such as the signal representing the target luminous flux or any other signals as described above for controlling operation of the lighting device 2 (e.g., change operational mode, receive sensor data or receive user preferences).

[0096] Alternatively, the controller 6,10 may be implemented as an electronic circuit. FIG. 2A-2D schematically depict a dimming behavior according to an embodiment. In particular, FIG. 2A depicts a cumulative relative luminous flux, wherein the relative first luminous flux is defined as a ratio of the first luminous flux and a total luminous flux wherein the relative second luminous flux is defined as a ratio of the second luminous flux and the total luminous flux; in this case, the total luminous flux equals a sum of the first luminous flux and the second luminous flux. The downward striped area 26 represents the second (green) luminous flux and the vertically striped area 24 represents the first (white) luminous flux. In the depicted example, the first (white) luminous flux and the second (green) luminous flux together form the total luminous flux, which is assumed to be equal to the target luminous flux. The dash-dotted lines indicate the first target luminous flux value 21 (in this example 200 lumen) and the second target luminous flux value 23 (in this example 40 lumen). Below the second luminous flux, the light is green only, and above the first luminous flux value, the light is white only (with a certain correlated color temperature). In other embodiments, there may be green and / or white contributions through the entire range of target luminous flux values.

[0097] It is noted that in this example, the first and second target luminous flux values may be selected anywhere between 40-200 lumen, provided that the first target luminous flux value 21 is larger than the second target luminous flux value 23. In this example, the contribution of the white light decreases from 100 % to 0 % between the first and second target luminous flux values, and the contribution of the green light increases from 0 % to 100 % between the first and second target luminous flux values.

[0098] In the depicted example, the second target luminous flux value 23 is 20% of the first target luminous flux value 21. In other embodiments, the second target luminous flux may be zero, or alternatively, some other percentage of the first target luminous flux, e.g., about 25 %, 30 %, 40 %, 50 %, 60 %, 65 %, or 75 %. The distance between the first and 2024PF80154 18 second target luminous flux values is a measure for how quickly the emitted light changes from (predominantly) white to greenish or predominantly green.

[0099] When the second target luminous flux value is larger than zero, or larger than a minimum target luminous flux of the lighting system, the ratio between the second (green) luminous flux and the first (white) luminous flux may be constant in the interval between the second target luminous flux and zero luminous flux, respectively the minimum target luminous flux of the lighting system.

[0100] It will be evident to the skilled person that the specific numerical values are only exemplary. Some lighting systems may have a minimum luminous flux that is greater than zero, some lighting systems may have a maximum luminous flux that is greater than 400 lumen or smaller than 400 lumen, et cetera.

[0101] FIG. 2B depicts the corresponding cumulative luminous flux, wherein the cumulative luminous flux is defined as the sum of the first (white) luminous flux and the second (green) luminous flux, wherein again the downward striped area represents the second (green) luminous flux and the vertically striped area represents the first (white) luminous flux.

[0102] FIG. 2C depicts the corresponding luminous flux ratio 27, wherein the luminous flux ratio is defined as the ratio between the first (white) luminous flux and the second (green) luminous flux, for the interval between the first and second target luminous flux values, where both the first and second luminous fluxes are non-zero. The resulting graph is a strictly increasing graph (for increasing target luminous flux), indicating that the ratio between the first (white) luminous flux and the second (green) luminous flux decreases with decreasing target luminous flux in the interval between the first target luminous flux value 21 and the second target luminous flux value 23.

[0103] In the depicted example, the relative second (green) luminous flux follows a super-linear behavior in the interval between the first and second luminous flux values. That is, for any intermediate target luminous flux value in the interval between the first and second target luminous flux values, the relative second luminous flux (solid line 20) is larger than a linear interpolation (dotted line 22) of the second luminous flux at the first and second target luminous flux values. In a formula, that may be expressed as: wherein / , / x, and I2represent, respectively, the intermediate target luminous flux value, the first target luminous flux value 21, and the second target luminous flux value 23, and wherein g( ) represents the relative second luminous flux at the target luminous flux value / , i.e., 2024PF80154 19 wherein G( / ) represents the second luminous flux and W ( / ) represents the first luminous flux at the target luminous flux value I. In other embodiments, the relative second luminous flux may be defined as the ratio between the second luminous flux and the target luminous flux value.

[0104] Similarly, the relative first (white) luminous flux follows a sub-linear behavior in the interval between the first and second luminous target flux values. That is, for any intermediate target luminous flux value in the interval between the first and second target luminous flux values, the relative first luminous flux is smaller than a linear interpolation of the first luminous flux at the first and second target luminous flux values. In a formula, that may be expressed as: wherein w( / ) represents the relative first luminous flux at the target luminous flux value / , i.e.,

[0105] In other embodiments, the relative first luminous flux may be defined as the ratio between the first luminous flux and the target luminous flux value.

[0106] By ensuring that the first (white) luminous flux decreases relative to the second (green) luminous flux as the total luminous flux decreases, the light becomes more greenish as the lights intensity becomes lower. In other words, a dimming profile is achieved wherein the emitted light becomes more greenish and less white, as the emitted light becomes more dim. This may also be referred to as “dim-to-green” behavior. As low-intensity green light is known to be beneficial (at least relative to light with different colors at the same intensity) for persons suffering from certain neurological disorders, such as migraine, such dim-to-green behavior can reduce complaints from such persons.

[0107] By using a super-linear behavior for the second (green) luminous flux during dimming, the light moves to green relatively fast, so that a beneficial effect may be achieved relatively fast.

[0108] Fig. 2D is a graph of the CIE 1931 x,y chromaticity space. The outer contour represents the chromaticity of narrow-band monochromatic light with wavelengths ranging from 440-650 nm. The stars represent exemplary LED sources of the lighting device shown in Fig. 1 A, namely, a green LED 32i (with peak wavelength of 530 nm), and a white LED 322 2024PF80154 20

[0109] (with a correlated color temperature of 4000 K). The shaded area 38 is the chromaticity area that corresponds to white light as defined by ANSI C78.377-2017, with a correlated color temperature of 2200-6500 K.

[0110] The trajectory 34 between the white light source 322 and the green light source 32i indicates the chromaticity of the emitted light for target luminous flux values in the interval between the first and second target luminous flux values. The tick marks indicate equidistant points in target luminous flux values (in this example at a distance of 10 Im). It can be seen that the distance between the tick marks is larger closer to the white light source (corresponding to a high target luminous flux values), which shows again the super-linear behavior of the second luminous flux.

[0111] In some embodiments, a user may program a specific dim-to-green behavior based on personal preferences.

[0112] FIG. 3 A-3D schematically depict a dimming behavior according to an embodiment. The figures are analogous to Fig. 2A-2D, respectively. However, in this embodiment, the lighting system further comprises a second white light source 32s, e.g., as described above with reference to Fig. IB. As shown in Fig. 3D, in this example, the first white light source 322 has a CCT of 2200 K and the second white light source 32s has a CCT of 6500 K. In the depicted example, the lighting system first exhibits dim-to-warm behavior 34i between the third and first target luminous flux values, and dim-to-green behavior 342 between the first and second target luminous flux values.

[0113] Thus, in this example, the controller of the lighting system is configured to determine, based on the target luminous flux, a third luminous flux for the second white light source (indicated with rising shading). As can be seen in Fig. 3C, the ratio 29 between the third luminous flux (cool white) and the first luminous flux (warm white) decreases with decreasing target luminous flux in the interval between the third target luminous flux value 25 and the first target luminous flux value 21; this ratio is indicated with the dotted line 29. Fig. 3C also shows that the ratio between the first luminous flux and the second luminous flux (the ratio indicated with the solid line 27) decreases with decreasing target luminous flux in the interval between the first target luminous flux value 21 and the second target luminous flux value 23.

[0114] In the example depicted in Fig. 3 A-D, the relative second (green) luminous flux 20 follows a sub-linear behavior in the interval between the first and second luminous flux values. In other embodiments, the dimming behavior may be linear or super-linear. 2024PF80154 21

[0115] In general, the controller may be configured to determine the luminous fluxes such that the ratio between the total white luminous flux and the total green luminous flux decreases with decreasing target luminous flux in the interval between the first target luminous flux value and the second target luminous flux value.

[0116] FIG. 4A-4D schematically depict a dimming behavior according to an embodiment. The figures are analogous to Fig. 2A-2D and 3 A-3D, respectively. In this embodiment, the lighting system also comprises a second white light source 32s, e.g., as described above with reference to Fig. IB. As shown in Fig. 4D, in this example, the first white light source 322 has a CCT of 2200 K and the second white light source 32s has a CCT of 6500 K. In the depicted example, the lighting system exhibits a combination of dim-to- warm behavior and dim-to-green behavior. However, different from the embodiment shown in Fig. 3 A-D, in this embodiment, all three luminous fluxes are non-zero between the second and third target luminous flux values.

[0117] As can be seen by comparing Fig. 4D with Fig. 3D, the addition of green light to the combination of high-CCT and low-CCT white light results in light that is white according to the ANSI standard (instead of slightly purplish), before turning towards the green chromaticity region. Moreover, in this example, the transition from dim-to-warm to dim-to-green is more gradual, which may result in a more natural experience.

[0118] In the example depicted in Fig. 4A-D, the relative second (green) luminous flux follows a sub-linear behavior in the interval between the first target luminous flux value 2h and a fourth target luminous flux value 2h, and a super-linear behavior in the interval between the fourth and second target luminous flux values. It is noted that, in principle, the first target luminous flux value 211 could be selected such that the lighting system exhibits a super-linear dim-to-green behavior over the entire interval between the first and second target luminous flux values.

[0119] FIG. 5A is a flowchart of a method according to an embodiment. The method may be executed by a lighting system as described herein, more specifically by the controller as described above. In general, the lighting system includes a lighting device comprising a green light source for emitting green light and a white light source for emitting white light.

[0120] A step 51 comprises receiving a signal representing a target luminous flux.

[0121] A step 53 comprises, in response to receiving the signal representing the target luminous flux, determining, based on the target luminous flux, a first luminous flux for the white light source and a second luminous flux for the green light source. 2024PF80154 22

[0122] A step 55 comprises controlling the white light source to emit the white light with the first luminous flux and controlling the green light source to emit the green light with the second luminous flux.

[0123] Herein, in a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with decreasing target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value.

[0124] FIG. 5B is a flowchart of a method according to an embodiment. The method may be executed by a lighting system as described herein, more specifically by the controller as described above. In general, the lighting system in this embodiment includes a lighting device comprising a green light source for emitting green light, a first white light source for emitting first white light with a first correlated color temperature, and a second white light source for emitting second white light with a second correlated color temperature higher than the first correlated color temperature.

[0125] The step 51 comprises receiving a signal representing a target luminous flux.

[0126] A step 54 comprises, in response to receiving the signal representing the target luminous flux, determining, based on the target luminous flux, a first luminous flux for the first white light source, a second luminous flux for the green light source, and a third luminous flux for the second white light source.

[0127] A step 56 comprises controlling the first white light source to emit the first white light with the first luminous flux, controlling the green light source to emit the green light with the second luminous flux, and controlling the second white light source to emit the second white light with the third luminous flux.

[0128] Herein, in a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with decreasing target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value. Moreover, a ratio between the third luminous flux and the first luminous flux may decrease with decreasing target luminous flux in an interval between a third target luminous flux value, higher than the first target luminous flux value, and the first target luminous flux value.

[0129] The lighting systems described herein may be used in a method for treating a neurological disorder, e.g., at least one of migraine, fibromyalgia, neuropathy, or chronic headaches. Such method comprises exposing a person suffering of the neurological disorder to light emitted by the lighting system in the first mode of operation as described above. 2024PF80154 23

[0130] FIG. 6 is a flowchart of a method according to an embodiment. The method may be executed by a lighting system as described herein, more specifically by the controller as described above. A step 61 comprises receiving a signal representative of a behavioral and / or physiological condition of a user. The behavioral or physiological condition may be indicative of a neurological disorder situation or an onset of the neurological disorder or an expected / predicted onset of the neurological disorder. The neurological disorder can be at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0131] A step 63 comprises activating a (predefined) first operating mode of a lighting system in response to receiving the signal representative of the behavioral and / or physiological condition of the user. In the first mode operation, the lighting system is configured for executing the method as described with reference to Fig. 5A or 5B.

[0132] FIG. 7A is a graph of the CIE 1931 x,y chromaticity space. The outer contour represents the chromaticity of narrow-band monochromatic light with wavelengths ranging from 440-650 nm. The stars represent the exemplary LED sources of the lighting device shown in Fig. IB, namely, a green LED 32i (with peak wavelength of 530 nm), a first white LED 322 (with a correlated color temperature of 6500 K), and a second white LED 32s (with a correlated color temperature of 2200 K). The shaded white-light area 38 is the chromaticity area that corresponds to white light as defined by ANSI C78.377-2017, with a correlated color temperature of 2200-6500 K.

[0133] The figure also shows 14 exemplary points 40i i4 in chromaticity space, listed in Table 1 (the row number in the table corresponds with the subscript on the reference number). The table comprises a direct green (DG) LED 40i, a direct amber (DA) LED 408, and six mixtures of those labelled DGA1-6 (corresponding to points 4O2-7). For spectra DGAB1-5, corresponding to points 4O9-13, different amounts of blue light where added to the spectra. Finally, point 40u represents a white light source with a correlated color temperature (CCT) of 2725 K.

[0134] Table 1. Chromaticity coordinates in the CIE 1931 x,y chromaticity space for several light sources. The light recipes rendered in bold were used in the experiment described with reference to Fig. 7B.

[0135] # label x y

[0136] 1 DG 0.172 0.732

[0137] 2 DGA1 0.251 0.671

[0138] 3 DGA2 0.309 0.627

[0139] 4 DGA3 0.353 0.595

[0140] 5 DGA4 0.401 0.557

[0141] 6 DGA5 0.455 0.515 2024PF80154 24

[0142] 7 DGA6 0.509 0.473

[0143] 8 DA 0.591 0.408

[0144] 9 DGAB1 0.288 0.530

[0145] 10 DGAB2 0.327 0.507

[0146] 11 DGAB3 0.370 0.479

[0147] 12 DGAB4 0.411 0.456

[0148] 13 DGAB5 0.329 0.425

[0149] 14 White 2725 K 0.458 0.411

[0150] FIG. 7B shows results of a perception test with seven participants, comparing two light sources with a yellowish-green chromaticity (labelled “DGA2” and “DGA4”), a yellowish light source (labelled “DGA6”), a standard white light source with a CCT of 2725 K (labelled “white”), and a simple direct green LED (labelled “DG”), measuring reading ability and visual comfort when exposed to these different light spectra.

[0151] The seven participants were shown the five different light spectra, in pairs of two. In each experimental trial, the participant was shown a first spectrum for 10 seconds, followed by a second spectrum for another 10 seconds. During the trial they were looking at a textbook that was illuminated by the test spectra. After the second spectrum, the participants gave their preference for either the first or second spectrum. In case they could not decide they had to randomly pick the first or second spectrum. Separate sessions were held for judging the visual comfort and readability of the text.

[0152] As shown in Fig. 7B, the yellowish-green color points (DGA2 & DGA4) in the above-defined chromaticity space have been rated as a somewhat (but significant) more comfortable light setting compared to white and yellowish light (white & DGA6), and considerably more comfortable than the direct green LED choice (DG). At the same time, participants reported it is easier to read (higher contrast) for the greenish color points (DG, DGA2, DGA4), than the white / yellowish color points (white, DGA6). This is likely due to green light creating a sharper image on the retina than white or yellowish light.

[0153] Thus, dimming towards a green color point provides better reading ability and / or comfort compared to, e.g., dimming towards warm white light color points at the same luminous flux.

[0154] Fig. 8 depicts a block diagram illustrating a data processing system as claimed in an embodiment.

[0155] As shown in Fig. 8, the data processing system 100 may include at least one processor 102 coupled to memory elements 104 through a system bus 106. As such, the data processing system may store program code within memory elements 104. Further, the 2024PF80154 25 processor 102 may execute the program code accessed from the memory elements 104 via a system bus 106. In one aspect, the data processing system may be implemented as a computer that is suitable for storing and / or executing program code. It should be appreciated, however, that the data processing system 100 may be implemented in the form of any system including a processor and a memory that is capable of performing the functions described within this specification.

[0156] The memory elements 104 may include one or more physical memory devices such as, for example, local memory 108 and one or more bulk storage devices 110. The local memory may refer to random access memory or other non-persistent memory device(s) generally used during actual execution of the program code. A bulk storage device may be implemented as a hard drive or other persistent data storage device. The processing system 100 may also include one or more cache memories (not shown) that provide temporary storage of at least some program code in order to reduce the number of times program code must be retrieved from the bulk storage device 110 during execution.

[0157] Input / output (I / O) devices depicted as an input device 112 and an output device 114 optionally can be coupled to the data processing system. Examples of input devices may include, but are not limited to, a keyboard, a pointing device such as a mouse, a touch- sensitive display, an external control system referred to herein, or the like. Examples of output devices may include, but are not limited to, a monitor or a display, speakers, the LED driver, or the like. Input and / or output devices may be coupled to the data processing system either directly or through intervening I / O controllers.

[0158] In an embodiment, the input and the output devices may be implemented as a combined input / output device (illustrated in Fig. 8 with a dashed line surrounding the input device 112 and the output device 114). An example of such a combined device is a touch sensitive display, also sometimes referred to as a “touch screen display” or simply “touch screen”. In such an embodiment, input to the device may be provided by a movement of a physical object, such as, e.g., a stylus or a finger of a user, on or near the touch screen display.

[0159] A network adapter 116 may also be coupled to the data processing system to enable it to become coupled to other systems, computer systems, remote network devices, and / or remote storage devices through intervening private or public networks. The network adapter may comprise a data receiver for receiving data that is transmitted by said systems, devices and / or networks to the data processing system 100, and a data transmitter for transmitting data from the data processing system 100 to said systems, devices and / or 2024PF80154 26 networks. Modems, cable modems, and Ethernet cards are examples of different types of network adapter that may be used with the data processing system 100.

[0160] As pictured in Fig. 8, the memory elements 104 may store an application 118. In various embodiments, the application 118 may be stored in the local memory 108, the one or more bulk storage devices 110, or apart from the local memory and the bulk storage devices. It should be appreciated that the data processing system 100 may further execute an operating system (not shown in Fig. 8) that can facilitate execution of the application 118. The application 118, being implemented in the form of executable program code, can be executed by the data processing system 100, e.g., by the processor 102. Responsive to executing the application, the data processing system 100 may be configured to perform one or more operations or method steps described herein.

[0161] In one aspect of the present invention, the data processing system 100 may represent a control system of a LED driver as described herein.

[0162] In another aspect, the data processing system 100 may represent a client data processing system. In that case, the application 118 may represent a client application that, when executed, configures the data processing system 100 to perform the various functions described herein with reference to a “client”. Examples of a client can include, but are not limited to, a personal computer, a portable computer, a mobile phone, or the like.

[0163] In yet another aspect, the data processing system 100 may represent a server. For example, the data processing system may represent an (HTTP) server, in which case the application 118, when executed, may configure the data processing system to perform (HTTP) server operations.

[0164] Various embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette 2024PF80154 27 drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on the processor 102 described herein.

[0165] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0166] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

2024PF80154 28CLAIMS1. A lighting system comprising a first white light source for emitting first white light with a first correlated color temperature, a green light source for emitting green light, and a controller for individually controlling the first white light source and the green light source; wherein the controller is configured to:- receive a signal representing a target luminous flux;- in response to receiving the signal representing a target luminous flux, determine, based on the target luminous flux, a first luminous flux for the first white light source and a second luminous flux for the green light source; and- control the first white light source to emit the first white light with the first luminous flux and control the green light source to emit the green light with the second luminous flux; and wherein, in a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with the target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value.

2. The lighting system as claimed in claim 1, wherein the green light source is a direct green solid-state light source, or wherein the green light source is a phosphor-converted solid-state light source.

3. The lighting system as claimed in claim 1 or 2, further comprising a second white light source for emitting second white light with a second correlated color temperature, the second correlated color temperature being higher than the first correlated color temperature; wherein the controller is further configured to:- determine, based on the target luminous flux, a third luminous flux for the second white light source; and2024PF80154 29- control the second white light source to emit the second white light with the third luminous flux; and wherein, in a second operational mode, a ratio between the third luminous flux and the first luminous flux decreases with the target luminous flux in the interval between the first target luminous flux value and the second target luminous flux value.

4. The lighting system as claimed in claim 3, wherein a ratio between the third luminous flux and the first luminous flux decreases with the target luminous flux in an interval between a third target luminous flux value, higher than the first target luminous flux value, and the first target luminous flux value.

5. The lighting system as claimed in any one of the preceding claims, wherein the controller is further configured to selectively activate the first operational mode based on at least one of:- a time of the day and / or a day of the week;- a signal from a switch provided on a device of the lighting device;- reception of an external switch signal via a communication interface of the lighting system;- detection of a speech command by the lighting system; or- behavioral and / or physiological analysis, by the lighting system, of a user.

6. The lighting system as claimed in claim 5, wherein the controller is configured to selectively activate the first operational mode based on behavioral and / or physiological analysis and wherein the behavioral and / or physiological analysis results in a signal indicative of a neurological disorder situation or an onset of the neurological disorder or an expected or predicted onset of the neurological disorder, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

7. The lighting system as claimed in any one of the preceding claims, wherein the controller is further configured to define or update first target luminous flux value and / or the second target luminous flux value in response to a signal received from a user interface.

8. The lighting system as claimed in any one of the preceding claims, wherein, in the first operational mode, for any intermediate target luminous flux value in the interval2024PF80154 30 between the first target luminous flux value and the second target luminous flux value, a relative second luminous flux is equal to or larger than a linear interpolation of the relative second luminous flux at the first target luminous flux value and the relative second luminous flux at the second target luminous flux value, wherein the relative second luminous flux is defined as a ratio of the second luminous flux and a sum of the first luminous flux and the second luminous flux.

9. The lighting system as claimed in any one of the preceding claims, wherein the green light has a peak wavelength between 495 nm and 570 nm, preferably between 520 nm and 560 nm.

10. The lighting system as claimed in any one of the preceding claims, wherein the second target luminous flux value is at most 75 %, at most 50 %, or at most 25 % of the first target luminous flux value.

11. A computer-implemented method for controlling a lighting device, the lighting device comprising a first white light source for emitting first white light with a first correlated color temperature, a green light source for emitting green light, the method comprising:- receiving a signal representing a target luminous flux;- in response to receiving the signal representing the target luminous flux, determining, based on the target luminous flux, a first luminous flux for the first white light source and a second luminous flux for the green light source; and- controlling the first white light source to emit the first white light with the first luminous flux and controlling the green light source to emit the green light with the second luminous flux; wherein, in a first operational mode, a ratio between the first luminous flux and the second luminous flux decreases with the target luminous flux in an interval between a first target luminous flux value and a second target luminous flux value, lower than the first target luminous flux value.

12. The method as claimed in claim 11, wherein, in the first operational mode, for any intermediate target luminous flux value in the interval between the first target luminous flux value and the second target luminous flux value, a relative second luminous flux is equal2024PF80154 31 to or larger than a linear interpolation of the relative second luminous flux at the first target luminous flux value and the relative second luminous flux at the second target luminous flux value, wherein the relative second luminous flux is defined as a ratio of the second luminous flux and a sum of the first luminous flux and the second luminous flux.

13. A computer program comprising instructions which, when executed by a controller of a lighting system as claimed in one of the claim 1 to 10, causes the data processing system to perform the method as claimed in claim 11 or 12.

14. A computer readable signal medium for transmitting a computer program as claimed in claim 13 or a non-transitory computer-readable storage medium having stored thereon a computer program as claimed in claim 13.

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