System and method for generating comfortable light

Abstract

A lighting device, a controller for the lighting device, and a method for using the lighting are disclosed. The lighting device comprises one or more light sources. The lighting device is configured to operate in a predefined first operation mode wherein the lighting device is configured to emit greenish white light. The greenish white light is white light as defined by ANSI C78.377-2017. The greenish white light has a relative M-cone-opic irradiance of at least 0.393, wherein the relative M-cone-opic irradiance is defined as a ratio between an M-cone-opic irradiance and a sum of an L-cone-opic irradiance, the M-cone-opic irradiance, and an S-cone-opic irradiance as defined in publication CIE S 026 / E:2018.

Description

[0001] SYSTEM AND METHOD FOR GENERATING COMFORTABLE LIGHT

[0002] FIELD OF THE INVENTION

[0003] This disclosure relates to a system and method for emitting white light, in particular to such system wherein the white light is perceived as comfortable.

[0004] BACKGROUND OF THE INVENTION

[0005] White light, as defined by the ANSI C78.377-2017 standard, is used for a wide range of applications, including home lighting and office lighting. However, white light may bring discomfort to persons exposed to it, in particular persons suffering from migraine or other neurological disorders such as fibromyalgia, neuropathy, or chronic headaches.

[0006] In light of the above, there is a need in the art for a system and method for emitting white light that increases the comfort of people exposed to it.

[0007] SUMMARY OF THE INVENTION

[0008] To that end, a lighting device is disclosed that is configurable to emit greenish white light. The invention is defined by the appended claims.

[0009] In an aspect, the current disclosure relates to a lighting device comprising one or more light sources. The lighting device is configured to operate in a predefined first operation mode wherein the lighting device is configured to emit greenish white light. The greenish white light is white light as defined by ANSI C78.377-2017. The greenish white light has a relative M-cone-opic irradiance of at least 0.39 and / or at least 2 / | 05CCT + 0.3256 and / or at least -3 / I 06CCT + 0.4044, wherein CCT denotes a correlated color temperature (in Kelvin) of the greenish white light, and wherein the relative M-cone-opic irradiance is defined as a ratio between an M-cone-opic irradiance and a sum of an L-cone- opic irradiance, the M-cone-opic irradiance, and an S-cone-opic irradiance of the greenish white light, the L-cone-opic irradiance, the M-cone-opic irradiance, and the S-cone-opic irradiance being as defined in publication CIE S 026 / E:2018.

[0010] In general, light may be defined as greenish light if it has a relative M-cone- opic irradiance of at least > min(2 / I O5CCT + 0.3256, 0.39, -3 / 106CCT + 0.4044). Greenish white light is light that is both greenish and white (as defined by ANSI C78.377- 2017).

[0011] It has been found that greenish light is more comfortable to people suffering from certain neurological conditions, such as migraine. Known white light spectra are not optimized for reducing discomfort associated with such neurological conditions (e.g., minimizing migraine headache intensity), and thereby can be unnecessary discomfortable for patients at a given light level. The embodiments described herein minimize this discomfort while maintaining (a minimum level) visual quality (e.g., expressed as a CCT, CRI and / or lux value).

[0012] In general, the higher the relative M-cone-opic irradiance, the more comfortable the light is perceived to be. Hence, in some embodiments, the relative M-cone- opic irradiance may be at least 0.392, at least 0.394, at least 0.396, at least 0.398, at least 0.40, at least 0.402, at least 0.404, at least 0.406, at least 0.408, or at least 0.41.

[0013] It is noted that the relative a-opic irradiance is independent of the absolute irradiance of a light source, and is independent of, e.g., the radiant flux (intensity) of the light source and of the distance between the light source and the observer. This can be understood by considering that the a-opic irradiances depend linearly on the (total) irradiance, so that the numerator and the denominator of the relative a-opic irradiance depend in the same way on the irradiance (and hence, distance), and the absolute irradiance cancels out. For example, assuming that the relation between absolute (a-opic) irradiance and distance follows an inverse square law, then, if the distance becomes twice as large, the a-opic irradiances in both the numerator and the dominator decrease by a factor of four, leading to the same dimensionless value for the relative a-opic irradiance.

[0014] The relative M-cone-opic irradiance Mrelis defined as:

[0015] M Mrei~ L + M + S' wherein L, M, and S represent, respectively, an L-cone-opic irradiance, an M- cone-opic irradiance, and an S-cone-opic irradiance of the emitted light. This value of ei is independent of the absolute irradiance.

[0016] The lighting device can be, e.g., a luminaire or a light fixture, or a system comprising a plurality of luminaires or light fixtures, in particular those configured for use in a home or office environment.

[0017] Because the lighting device has a predefined operation mode in which the lighting device emits greenish white light, the lighting device can do so consistently and repeatedly, for a prolonged duration. Some existing lighting devices may enable a user to program a device to minimize discomfort, but even in such applications, the user typically does not have full control over the spectral power distribution of the light emitted by the lighting device. By contrast, the devices as disclosed herein may have a spectral distribution that maximizes Mei, within one or more constraints (such as the light being considered white, and possibly other constraints based on, e.g., CRI, CCT, and / or lux level).

[0018] The embodiments in this disclosure were motivated by a desire to describe white light solutions that are spectrally tuned to minimize the discomfort due to (white) light exposure associated with neurological disorders, such as intensity of migraine headache. However, it has been found that such specifically tuned white light solutions are sometimes also perceived as more comfortable by person not suffering from (nor about to suffer from) a neurological disorder. For example, greenish light may improve the readability of black-on- white text.

[0019] In an embodiment, the white light has a Color Rendering Index, CRI, of at least 50, at least 60, at least 70, at least 75, or at least 80. In general, greenish white light tends to have a relatively low CRI, and the more greenish the light is (the higher the relative M-cone-opic irradiance), the lower (in general) the CRI. However, for certain applications, a minimal CRI may be required, in particular in office environments, and hence, a balance may be struck between a high relative M-cone-opic irradiance and a high CRI. It is noted that relative M-cone-opic irradiance and the CRI depend on the combination and the properties of the light sources that are used. By using different (combinations of) light sources, a higher Mei may be obtained with the same CRI. or conversely, a higher CRI with the same Mei.

[0020] As used herein, CRI refers to CRI Ra as defined in CIE Publication 13.3 (1995) ‘Method of Measuring and Specifying Colour Rendering Properties of Light Sources’.

[0021] In an embodiment, the lighting device is configurable to emit white light with different spectral power distributions, each spectral power distribution having a different correlated color temperature, CCT, and each spectral power distribution having a respective relative M-cone-opic irradiance of at least 0.39 and / or at least 2 / 105CCT + 0.3256 and / or at least -3 / 106CCT + 0.4044. In some embodiments, the respective relative M-cone-opic irradiances may be at least 0.392, at least 0.394, at least 0.396, at least 0.398, at least 0.40, at least 0.402, at least 0.404, at least 0.406, at least 0.408, or at least 0.41.

[0022] For some applications, in particular in home environments, it can be desirable to change the CCT of the emitted light, possibly in combination with dimming of the emitted light. By ensuring that a maximum Mei is observed for all spectra, a user may vary the CCT without suffering unnecessary discomfort. In some embodiment, a controller for / of the lighting device is configured to maximize ei for each setting, e.g., for each selected CCT value.

[0023] In an embodiment, at least one of the one or more light sources is configured to emit light with a chromaticity selected within a triangle 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. More in particular, the chromaticity may be selected from a triangle defined by (x, y) coordinates (0.291, 0.47), (0.465, 0.534) and (0.237, 0.748) according to the CIE 1931 x,y chromaticity space, or from a triangle defined by (x, y) coordinates (0.28, 0.52), (0.42, 0.575) and (0.237, 0.748) according to the CIE 1931 x,y chromaticity space. Light with a chromaticity in one of these triangles is greenish light that has been found to have a high relative M-cone-opic irradiance. Hence, greenish white light (with a high relative M-cone-opic irradiance) may be obtained by combining standard white light sources with a greenish light source as defined here. This also allows switching between normal white light (which may have, e.g., a higher CRI) and greenish white light by switching the greenish light source on or off.

[0024] In an embodiment, the lighting device is switchable between the first operation mode and a second operation mode, different from the first operation mode. In other embodiments, the lighting device only has the first operation mode. It is noted that an ‘off mode in which the lighting device does not emit any light, is not considered an operation mode in this context. In some embodiments, the lighting device may be switchable between more than two operation modes, e.g., three or more operation modes. In some of these operation modes, the lighting device may be configured to emit greenish white light, and in some of these operation modes the lighting device may be configured to emit light that is not greenish white light, e.g., normal white light or light according to a user’s customized settings, et cetera.

[0025] The lighting device being switchable between the first operation mode and the second operation mode allows the first operation mode to be selectively activated, for example, only when the increased comfort level is needed or desired, e.g., due to the presence of a person experiencing a neurological disorder.

[0026] In an embodiment, the second operation mode configures the lighting device to emit white light with a second spectral power distribution different from the first spectral power distribution that is optimized for at least one of energy consumption, CRI, or melanopic equivalent daylight illuminance. In an embodiment, the lighting device is configured to switch from the second operation to the first operation 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 the lighting device; reception of an external switch signal via a communication interface of the lighting device; detection of a speech command by the lighting device; or behavioral and / or physiological analysis, by the lighting device, of a user. These are some exemplary implementations that allow the lighting device to switch to and from the predefined first operation mode based on a signal indicative of a neurological disorder situation or an onset of the neurological disorder (e.g., migraine, fibromyalgia, neuropathy, or chronic headaches).

[0027] In an embodiment, the behavioral and / or physiological analysis results in a signal indicative of a neurological disorder situation or an onset of the neurological disorder, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0028] In a further aspect, embodiments in this disclosure are related to a controller for a lighting device, e.g., a lighting device as described above.

[0029] In particular, an aspect of this disclosure relates to a controller configured to switch a lighting device 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 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, wherein the behavioral or physiological condition is indicative of a neurological disorder situation or an onset of the neurological disorder, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0030] In an embodiment, the signal representative of the behavioral and / or physiological condition is based on: a time of the day and / or a day of the week; a signal from a switch electrically connected to the controller; reception of an external switch signal via a communication interface 8 of the controller; detection of a speech command by the controller; behavioral and / or physiological analysis, by the controller, to detect the behavioral and / or physiological condition of a user.

[0031] In an embodiment, the first spectral power distribution corresponds to greenish white light, the greenish white light being white light as defined by ANSI C78.377-2017, and the greenish white light having a relative M-cone-opic irradiance of at least 0.39and / or at least 2 / 105CCT + 0.3256 and / or at least -3 / I 06CCT + 0.4044, wherein CCT denotes a correlated color temperature of the greenish white light. In an embodiment, the greenish white light has a relative M-cone-opic irradiance of at least 0.392, at least 0.394, at least 0.396, at least 0.398, at least 0.40, at least 0.402, at least 0.404, at least 0.406, at least 0.408, or at least 0.41.

[0032] In an embodiment, the first spectral power distribution has a Color Rendering Index, CRI, of at least 50, at least 60, at least 70, at least 75, or at least 80.

[0033] In an embodiment, the lighting device is configurable to emit light with different spectral power distributions, each spectral power distribution having a different correlated color temperature, CCT, and each spectral power distribution having a respective relative M-cone-opic irradiance of at least 0.39 and / or at least 2 / 105CCT + 0.3256 and / or at least -3 / 106CCT + 0.4044, wherein CCT denotes a correlated color temperature of the greenish white light.

[0034] The lighting device may be configurable to emit light with different spectral power distributions by individually controlling the light output of a plurality of light sources.

[0035] In an embodiment, the second spectral power distribution is optimized for at least one of: energy consumption, CRI, or melanopic equivalent daylight illuminance.

[0036] In an aspect, this disclosure relates to a method for controlling a lighting device, e.g., a lighting device as described above. The lighting device is switchable between a first mode of operation wherein a first light with a first spectral power distribution is emitted (e.g., greenish white light) and a second mode of operation wherein a second light with a second spectral power distribution is emitted. The method 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, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches. In response to receiving the signal representative of the behavioral and / or physiological condition of the user, the lighting device is caused to switch between the second mode of operation and the first mode of operation. In general, the controller may be configured to control a spectral distribution and, optionally, an intensity, of the emitted light. The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may, e.g., refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as, e.g., changing a voltage and / or current supplied to an element, etc. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior of an element based on output or other properties of the element.

[0037] A lighting device as described herein may comprise one or more light sources. The one or more light sources of the lighting device may comprise one or more controllable radiation sources, e.g., LED radiation sources, HID radiation sources, laser radiation sources, or other suitable radiation sources. The one or more controllable radiation sources may include means for controlling a spectrum of the emitted radiation, e.g., through filtering and / or concentrating the generated radiation. The radiation filters may be configured to selectively block, in part or in full, radiation of one or more predetermined wavelength regions. The radiation concentrators may be configured to concentrate radiation of a specific wavelength or wavelength range. Filters and concentrators can also be combined, e.g., by wavelength conversion, reducing an intensity of radiation of a first wavelength (filtering) while increasing radiation of a second wavelength (concentrating).

[0038] The one or more radiation filters may have, for instance, controllable radiation filtering properties and / or a controllable position. Similarly, the one or more radiation concentrators may have, for instance, controllable radiation concentrating properties and / or a controllable position. The controllable position may allow the filters and / or concentrators to be selectively inserted and removed in front of a radiation source.

[0039] As used herein, radiation refers to electromagnetic radiation, in particular to radiation in the visible part of the electromagnetic spectrum (also referred to as light), e.g., radiation with a wavelength between 380-780 nm, more in particular with a wavelength between 400-750 nm.

[0040] Thus, a lighting device as described herein may be controlled using this method. The method may be executed, for example, by a controller as described herein.

[0041] 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.

[0042] 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. 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] In another aspect, this disclosure relates to a method for treating a neurological disorder, preferably the neurological disorder comprising at least one of migraine, fibromyalgia, neuropathy, or chronic headaches, the method comprising: exposing a person suffering of the neurological disorder to greenish white light emitted by the lighting device as described above in the first operation mode.

[0044] 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, microcode, 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 product embodied in one or more computer readable medium(s) having computer readable program code embodied, e.g., stored, thereon.

[0045] 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.

[0046] 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.

[0047] 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 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).

[0048] 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.

[0049] 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.

[0050] 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.

[0051] The flowcharts 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 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.

[0052] 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.

[0053] 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.

[0054] BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Aspects of the invention will be explained in greater detail by reference to exemplary embodiments shown in the drawings, in which:

[0056] Fig. 1 A and IB schematically illustrate systems for emitting greenish white light according to embodiments;

[0057] Fig. 2A is a graph showing a measure of a change in headache intensity as a function of light color and intensity, and FIG. 2B is a graph showing a relation between an observed change in headache intensity and a relative M-cone-opic irradiance;

[0058] Fig. 3 shows relative M-cone-opic irradiance Mrel values for commercially available white light LED sources;

[0059] Fig. 4A-E show spectra corresponding to various solutions for greenish white light with respective CCTs of 3000 K and 5000 K;

[0060] Fig. 5A and 5B show the possibilities of optimizing an existing tunable light source to optimize comfort by maximizing relative M-cone-opic irradiance values for a HUE device;

[0061] Fig. 6 is a flowchart of a method according to an embodiment; and

[0062] Fig. 7 illustrates a data processing system according to an embodiment.

[0063] DETAILED DESCRIPTION OF THE DRAWINGS

[0064] In the figures, identical reference numbers indicate identical or similar elements.

[0065] Fig. 1 A schematically illustrates a system for emitting greenish white light according to a first embodiment. A lighting device 2 comprises one or more light sources 4i 4. The lighting device 2 can be, e.g., a luminaire of light fixture. The lighting device 2 may be configured for home and / or office use, and may be embodied as, e.g., a personal (desk) lamp or a ceiling luminaire. In embodiments with more than one light source, the one or more light sources 4, 4 may have different spectral characteristics. For example, the embodiment shown in Fig. 1 A comprises four Gaussian emitters, in this case LEDs. Other embodiments may use (additional or alternative) different light sources, e.g., HID source, laser sources, incandescent light sources, et cetera.

[0066] The lighting device 2 has at least a first predefined operation mode in which a combined spectrum of the one or more light sources 4I 4 corresponds to greenish white light. For example, the lighting device 2 may comprise a single greenish white light source, or a standard white light source and a greenish light source, or a plurality of light sources with spectral distributions covering a substantial part of the visible spectrum, e.g., a red, green, blue, and optionally yellow light source. In case the lighting device 2 comprises a plurality of light sources, each with a different spectral distribution of emitted light, such as a standard white light source, a greenish light source, a red and / or green and / or blue and / or yellow light source, each of the plurality of light sources may be individually controllable in terms of intensity of emitted light, e.g., by individually controlling a power or current supplied to each of the plurality of light sources, such the combined spectrum, more particularly the spectral power distribution of the combined light emitted from the plurality of light source provides, in the first predefined operation mode, the greenish white light.

[0067] The greenish white light is white light as defined by ANSI C78.377-2017. The greenish white light has a relative M-cone-opic irradiance of at least 0.39 and / or at least 2 / 105CCT + 0.3256 and / or at least 3 / 106CCT + 0.4044, wherein CCT denotes a correlated color temperature of the greenish white light. These parameters will be discussed in more detail below with reference to Fig. 3. In some embodiments, the relative M-cone- opic irradiance may be at least 0.392, at least 0.394, at least 0.396, at least 0.398, at least 0.40, at least 0.402, at least 0.404, at least 0.406, at least 0.408, or at least 0.41.

[0068] If the lighting device 2 comprises light sources with more than three different spectra, there are generally different settings that would result in spectra with the same chromaticity (i.e., the system is essentially overdetermined). However, different settings with the same chromaticity may have different relative M-cone-opic irradiances, as these depend on the full spectrum, more specifically the spectral power distribution. Hence, in such systems, it is possible to optimize for maximal relative M-cone-opic irradiance, increasing a user’s comfort without changing the chromaticity (e.g., CCT) of the light.

[0069] For example, the lighting device 2 may be optimized for maximum relative M- cone-opic irradiance, whilst having a fixed CCT and lux level. Such a lighting device 2 may be used as a light source for a single person in the home environment or as a general light source for a group of people like in an office environment. In a further example, the lighting device 2 is optimized for maximum relative M-cone-opic irradiance, have a fixed CCT, but is dimmable in lux level. Lowering the lux level may increase a user’s comfort (e.g., alleviate a migraine headache), while the spectrum ensures maximum comfort (minimum headache) at any lux level.

[0070] In a third example, the lighting device 2 is tunable in CCT, and dimmable in lux level, possibly in a correlated manner (e.g., lower lux levels being associated with lower CCTs). Different CCTs require different spectra. Hence, the lighting device 2 may be optimized for maximal relative M-cone-opic irradiance at each CCT, or at two or more CCT values using an interpolation (and possibly extrapolation) algorithm for intermediate CCT values. Changing the spectrum may require individually controlling the one or more light sources 4I 4 (which, in this case, may be individually controllable light sources).

[0071] In an embodiment, at least one of the one or more light sources 4I 4 emits light with a chromaticity selected within a triangle 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. More in particular, the chromaticity may be selected from a triangle defined by (x, y) coordinates (0.291, 0.47), (0.465, 0.534) and (0.237, 0.748) according to the CIE 1931 x,y chromaticity space, or from a triangle defined by (x, y) coordinates (0.28, 0.52), (0.42, 0.575) and (0.237, 0.748) according to the CIE 1931 x,y chromaticity space. Light with a chromaticity in one of these triangles is greenish light that has been found to have a high relative M-cone-opic irradiance. Hence, greenish white light (with a high relative M-cone-opic irradiance) may be obtained by combining standard white light sources with a greenish light source as defined here. This also allows switching between normal white light (which may have, e.g., a higher CRI) and greenish white light by switching the greenish light source on or off.

[0072] The lighting device 2 may further comprise a controller 6, and, optionally, a communication interface 8 communicatively connected to the controller 6. Certain embodiments are related specifically to such a controller 6. The controller 6 may be implemented as a data processing system as described below with reference to Fig. 7. The controller 6 may individually control the power or current supplied to each of the one or more light sources 4, 4 to thereby individually control the light output of the one or more light sources 4, 4 and thus control the spectral power distribution of the emitted, combined light from the one or more light sources 41-4. Depending on the implementation, the controller 6 may cause the lighting device 2 to switch between the first operation mode and one or more further operation modes. For example, the lighting device 2 may have a second operation mode, different from the first operation mode, in which second operation mode the lighting device 2 is configured to emit white light with a different spectral power distribution than the white light emitted in the first operation mode. For example, the white light emitted in the second operation mode may be optimized for at least one of energy consumption, CRI, or melanopic equivalent daylight illuminance, whereas the white light emitted in the first operation mode may be optimized for relative M-cone-opic irradiance.

[0073] The controller 6 may activate or deactivate the first operation mode in response to a signal received from the communication interface 8. The communication 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 of a neurological disorder. 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.

[0074] 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. These options will be described in more detail with respect to Fig. IB.

[0075] 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.

[0076] One or more control parameters for the one or more light sources 41 4 corresponding to the first operation mode may be stored in a memory of the controller 6. Such control parameters may include a power level, a current level or PWM signal for driving the light sources 41-4.

[0077] 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 and / or physiological analysis may result in a signal indicative of a neurological disorder situation or an onset of the neurological disorder, preferably the neurological disorder comprising at least one of migraine, fibromyalgia, neuropathy, or chronic headaches. In a further aspect, embodiments in this disclosure are related to the controller 6 for a lighting device 2, e.g., the lighting device 2 as described above.

[0078] Fig. IB schematically illustrates a system for emitting greenish white light according to a second embodiment. The system comprises a lighting device 2 (e.g., as described above with reference to Fig. 1 A) and a further (possibly external) data processing device 20 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 further device 20 and, optionally, sensor device 10.

[0079] 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 or an onset of the neurological disorder. Typical examples of neurological disorders comprise at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0080] In some embodiments, the further device 20 and the controller 6 may be integrated in a single data processing device, e.g., as described below with reference to Fig. 7. In some embodiments, the sensor device 10 can be integrated into the lighting device 2.

[0081] The sensor device 10 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 of a neurological disorder.

[0082] The sensor device 10 can be or comprise a camera for capturing an image or a video stream of the user 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, or for emotion recognition (such as pain or tiredness), et cetera, which may be indicative of the presence or onset of a neurological disorder.

[0083] The sensor device 10 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 of a neurological disorder may be determined.

[0084] The sensor device 10 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 of a neurological disorder.

[0085] For example, the user 1 can switch between regular white light and greenish white light (e.g., light with a maximum relative M-cone-opic irradiance), for example using a physical switch, a voice command, a gesture command, et cetera. The greenish white light may be at the same lux level as the regular white light, or lower.

[0086] In a further example, an additional sensor (e.g. a camera 10) may detect / recognize the onset 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 proactively change the light setting to the greenish white light (and possibly reduced lux).

[0087] Fig. 2A is a graph showing a measure of a change in headache intensity as a function of light color and intensity. More in particular, the graph is a bar graph showing a change in headache intensity (mean ± SEM) reported by patients in response to exposure to white light (solid black bars), blue light (vertical stripes), green light (rising stripes), amber light (horizontal stripes) and red light (falling stripes), and where the change in headache intensity is reported in VAS units, which stands for verbal analogue scale, by the patients. The change in VAS is referred to as AVAS. For each color, the change in headache intensity is shown for light intensities of 1, 5, 20, 50, and 100 lux. The figure has been reproduced from Noseda et al., ‘Migraine photophobia originating in cone-driven retinal pathways’, Brain 139:7 (2016), pages 1971-1986, which is hereby incorporated by reference in its entirety.

[0088] Fig. 2A thus reports the results of an experiment in which spectral tuning of light provided to migraine patients was assessed based on a model of self-reported headache intensity in migraine patients exposed to different colors and intensities of light. In this study, migraine patients during a migraine attack were first allowed to sit in a dimly lit room for 20 min. The light was then turned off and for 3 min and the patients were asked to verbally rate their headache intensity on a scale of 0-10. This rate was considered as baseline. Then, the participants were exposed to full-field light of different colors and intensity. Intensity was incrementally increased (1, 5, 20, 50, 100 cd / m2) every 30 seconds. While looking at the light the participants were asked to describe the change in headache intensity. The order of the color presentation was as depicted in Fig. 2A, i.e., white first, followed by blue, green amber and red. As a reference, 1 cd / m2provides a background light that is just above darkness whereas 100 cd / m2is about equivalent to a normally lit office space.

[0089] The figure shows that green light may reduce the intensity of migraine headaches. This is consistent with findings that green light therapy can have a positive effect on pain reduction. For example, it has been shown in the art 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. These studies provide evidence for the potential benefits of green light therapy in reducing pain and improving quality of life. However, more research is needed to fully understand the mechanisms of action and determine optimal treatment protocols.

[0090] The data in Fig. 2A clearly show the general trend that headache intensity increases with increasing light intensity. However, green light seems to be the mildest, even showing a trend in reduction in headache intensity for the lowest light intensities. At a given light intensity (lux level) green light shows the lowest headache intensity. Photosensitivity is typically expected to depend on the number of photons captured by the visual system. However, calculations using the available data from the Noseda et al. publication show that the smaller number of photons for green light could not explain the observed differences in AVAS (the change in headache intensity, see Fig. 2A).

[0091] Further, green light therapy typically uses only green light. However, in many cases (e.g., home or office environments, possibly with other people not suffering from a light-sensitive neurological disorder present), it is preferable to use white light rather than green light. Hence, a further study of the available data from the Noseda et al. publication was conducted to derive a mathematical model for predicting the change in headache intensity associated with a certain light exposure, based on the stimulations of the L, M and S cones of the human visual system by the spectral composition of the light exposure. Typically, green light (predominantly M-cone stimulation) reduces the reported headache intensity, whereas blue (S-cones) and red (L-cones) increase the headache intensity. The results showed that the relative M-cone-opic irradiance of a spectral power distribution (as defined herein) and the absolute light intensity of light can be used to predict changed in headache intensity.

[0092] Fig. 2B is a graph showing the relation between an observed AVAS value (as shown in Fig. 2A) and a corresponding relative M-cone-opic irradiance. As the M-cone-opic irradiance is independent of the light intensity, the same M-cone-opic irradiance value is obtained for all light intensities using the same spectral power distribution of the light source light, with different AVAS values corresponding to the different light intensities. From left to right, the relative M-cone-opic irradiances correspond to blue, red, amber, white, and green light.

[0093] The relative M-cone-opic irradiance Mrelis defined as a ratio between the M- cone-opic irradiance M and the sum of the L-cone-opic irradiance L, the M-cone-opic irradiance M, and the S-cone-opic irradiance S (again, as defined in publication CIE S 026 / E:2018), i.e., wherein L, Aland S are the L-cone-opic irradiance, the M-cone-opic irradiance, and the S- cone-opic irradiance of the emitted light, defined as the irradiance of the emitted light weighted by the L-cone, M-cone and S-cone spectral sensitivity curve respectively.

[0094] In general, light may be defined as greenish light if it has a relative M-cone- opic irradiance of at least 0.39 and / or at least 2 / 105CCT + 0.3256 and / or at least 3 / 106CCT + 0.4044. Greenish white light is light that is both greenish and white (as defined by ANSI C78.377-2017). It is noted that although white light that is on the ‘green’ side of the Planckian curve tends to have higher relative M-cone-opic irradiance values than white light that is on the ‘purple’ side of the Planckian curve, not all white light color points at the ‘green’ side of the Planckian curve are considered greenish as defined in this application with reference to the relative M-cone-opic irradiance ranges defined in this application.

[0095] It has been found that greenish light is more comfortable for people suffering from certain neurological conditions, such as migraine. Known white light spectra are not optimized for reducing discomfort associated with such neurological conditions (e.g., minimizing migraine headache intensity), and thereby can be unnecessary discomfortable for patients at a given light level. The embodiments described herein minimize this discomfort while maintaining (a minimum level) visual quality (e.g., expressed as a CCT, CRI or lux value). In general, the higher the relative M-cone-opic irradiance, the more comfortable the light is perceived to be. Hence, in some embodiments, the relative M-cone- opic irradiance may be at least 0.392, at least 0.394, at least 0.396, at least 0.398, at least 0.40, at least 0.402, at least 0.404, at least 0.406, at least 0.408, or at least 0.41; and / or at least 2+105CCT + 0.328, at least 2xl0"5CCT + 0.33, at least 2xl0"5CCT + 0.335, or at least 2+105CCT + 0.34; and / or at least -3 / 106CCT + 0.406, at least -3 / 106CCT + 0.408, or at least -3 / 106CCT + 0.41, at least -3 / 106CCT + 0.42.

[0096] It is noted that the relative a-opic irradiance is independent of the absolute irradiance of a light source, and is independent of, e.g., the radiant flux (intensity) of the light source and of the distance between the light source and the observer. This can be understood by considering that the a-opic irradiances depend linearly on the (total) irradiance, so that the numerator and the denominator of the relative a-opic irradiance depend in the same way on the irradiance (and hence, distance), and the absolute irradiance cancels out. For example, assuming that the relation between absolute (a-opic) irradiance and distance follows an inverse square law, then, if the distance becomes twice as large, the a-opic irradiances in both the numerator and the dominator decrease by a factor of four, leading to the same dimensionless value for the relative a-opic irradiance.

[0097] Fig. 3 shows relative M-cone-opic irradiance values for a set of commercially available LED-based white light sources with a CRI Ra > 60. The relative M-cone-opic irradiance value was computed for this collection of LED-based white light sources, using the formula of eq. (1), and the results were plotted against CCT. It can be seen that all light sources have a relative M-cone-opic irradiance Mrel< 0.39 and Mrel< 2 x 10-5CCT + 0.3256 and Mrei< —3 x 10-6CCT + 0.4044 (indicated with the dashed line).

[0098] Clearly, even within a fixed CCT category there is some 10-25% variation in relative M-cone-opic irradiance. This would make one particular light source more suitable for minimizing migraine headache than another.

[0099] As current light sources have not been specifically designed to maximize the relative M-cone-opic irradiance, even more comfortable light sources may be designed by using ei in a cost function of an optimization algorithm. For example, the inventors have devised spectral distributions that have specific requirements for CCT and CRI, while maximizing relative M-cone-opic irradiance, and thus minimizing the predicted headache intensity, using a combination of 4 Gaussian emitters. These are shown in Fig. 4A-D. These spectra create white light according to the ANSI definition and have a relative M-cone-opic irradiance value above what is commercially available. The center wavelengths, width (FWHM) and intensity ratios of these 4 Gaussians were optimized in software to derive at the spectra shown in Fig. 4A-D.

[0100] Fig. 4A-D show spectra corresponding to specific solutions for greenish white light with respective CCTs of 3000 K and 5000 K. The spectra shown in Fig. 4A-D were optimized for maximal relative M-cone-opic irradiance subject to the condition CRI Ra > 60, and some examples with relatively high and low Ra values were manually selected. Further examples are provided in Table 1. The spectra shown in Fig. 4A-D correspond to solutions #3, #4, #7, and #8, respectively.

[0101] Table 1. Parameters of greenish white light spectra created by four Gaussian emitters with respective central wavelengths 1-4, FWHM W1-4, and relative intensities for five different correlated color temperature categories ranging from 2200 K - 6500 K. The solutions were optimized for maximal relative M-cone-opic irradiance subject to the condition CRI Ra > 60. The spectra listed in Table 1 are plotted as color points in CIE u’v’ color space and relative to the Planckian curve and the CCT categories (quadrangles) mapped in CIE u’v’ color space in Fig 4E. What is to be noted in general is that, in extreme CCT categories such as for example extreme cold white at 6500 K and extreme warm white at 2200 K, these spectra may be referred to as bluish white light and reddish white light, respectively, but they are shifted, within their CCT category, towards green. Therefore, the term “greenish white light” as used herein may also be referred to “green-shifted white light”.

[0102] Fig. 5A and 5B show the possibilities of optimizing an existing tunable light source to optimize comfort by maximizing relative M-cone-opic irradiance values.

[0103] The light output of a HUE Al 9 bulb, available from the applicant at www.philips-hue.com, having R, G, B primaries and a 2200 K and 4000 K white primary was simulated. For the range of possible drive value combinations for these 5 primaries, the spectral light output and the relative M-cone-opic irradiance was calculated.

[0104] When restricting the color point to 0.35 < x < 0.55 and 0.35 < y < 0.45, a rectangular area in the white zone surrounding both the 2200 K and the 4000 K white primaries (shown in Fig. 5A), the relative M-cone-opic irradiance vs lux values for these color points is shown in Fig. 5B. Fig. 5B shows that for each lux level there exists an optimum setting for the HUE A 19 bulb that maximizes the relative M-cone-opic irradiance. In other words, there exists an optimum dimming curve for a multi-primary source such as the HUE A19 bulb that maximizes the relative M-cone-opic irradiance. In an embodiment, the lighting device is configured to follow such a dimming curve.

[0105] In more general terms, either the light sources or primaries of the lighting device are selected such that a combined light output from the light sources or primaries of the lighting device is capable of providing lighting device light characterized by a spectral power distribution that complies with the relative M-cone-opic irradiance ranges claimed herein, and / or the controller is configured to control light sources or primaries of the lighting devices to provide lighting device light characterized by a spectral power distribution that complies with the relative M-cone-opic irradiance ranges claimed herein. It has been shown that not all white light spectral power distributions comply with this relative M-cone-opic irradiance requirement and that a purposeful selection of light sources or primaries and / or a purposefully control of light sources or primaries is needed to be able to create a greenish white light spectral power distribution as defined herein. More specifically, it has been shown that no commercially available white light lighting devices comply with the relative M-cone- opic irradiance requirement as claimed herein. It is noted that the relative M-cone-opic irradiance is not specified by reference to a contribution of the green component in a spectral power distribution as the M-cone sensitivity curve also shows sensitivity of M-cones to cyan and yellow components in the spectral power distribution. Further, the relative M-cone-opic irradiance is not only specified with reference to an M-cone sensitivity but also takes into account L-cone and S-cone sensitivity.

[0106] Fig. 6 is a flowchart of a method according to an embodiment. More in particular, Fig. 6 shows a method for controlling a lighting device that is switchable between a first mode of operation wherein a first light with a first spectral power distribution is emitted (e.g., greenish white light) and a second mode of operation wherein a second light with a second spectral power distribution is emitted (e.g., non-greenish white light). For example, the method may be performed by a lighting system as described above, e.g., with reference to Fig. IB.

[0107] A step 31 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, preferably the neurological disorder comprising at least one of migraine, fibromyalgia, neuropathy, or chronic headaches.

[0108] A step 33 comprises, in response to receiving the signal representative of the behavioral and / or physiological condition of the user, causing the lighting device to switch between the second mode of operation and the first mode of operation. In particular, the lighting device may switch to a mode of operation wherein the lighting device emits greenish white light as defined herein in response to receiving a signal representative of the presence or onset of the neurological disorder.

[0109] Fig. 7 depicts a block diagram illustrating a data processing system as claimed in an embodiment.

[0110] As shown in Fig. 7, 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 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.

[0111] 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.

[0112] 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.

[0113] In an embodiment, the input and the output devices may be implemented as a combined input / output device (illustrated in Fig. 7 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.

[0114] 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 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.

[0115] As pictured in Fig. 7, 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. 7) 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.

[0116] In one aspect of the present invention, the data processing system 100 may represent a control system of a LED driver as described herein.

[0117] 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.

[0118] 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.

[0119] 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 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. 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.

[0120] 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

CLAIMS1. A lighting device comprising:- one or more light sources, and- a controller configured to control the one or more light sources in terms of a light output to be emitted by the one or more light sources, the combined light output from the one or more light sources being lighting device light, wherein the lighting device is configured to operate in a predefined first operation mode wherein the controller is configured to control the light output emitted by the one or more light sources to emit lighting device light being greenish white light, the greenish white light being white light as defined by ANSI C78.377-2017, and the greenish white light having a relative M-cone-opic irradiance of at least 0.39 and / or at least 2 / | 05CCT + 0.3256 and / or at least -3 / I 06CCT + 0.4044, wherein CCT denotes a correlated color temperature of the greenish white light, and wherein the relative M-cone-opic irradiance is defined as a ratio between an M- cone-opic irradiance and a sum of an L-cone-opic irradiance, the M-cone-opic irradiance, and an S-cone-opic irradiance as defined in publication CIE S 026 / E:2018.

2. The lighting device as claimed in claim 1, wherein the greenish white light has a Color Rendering Index, CRI, of at least 50, preferably at least 80.

3. The lighting device as claimed in claim 1 or 2, wherein the lighting device is configurable to emit white light with different spectral power distributions, each spectral power distribution having a different correlated color temperature, CCT, and each spectral power distribution having a respective relative M-cone-opic irradiance of at least 0.39 and / or at least 2xl0"5CCT + 0.3256 and / or at least -3 / 106CCT + 0.4044.

4. The lighting device as claimed in any one of the previous claims, wherein at least one of the one or more light sources is configured to emit light with a chromaticity selected within a triangle 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.

5. The lighting device as claimed in any one of the previous claims, wherein the greenish white light has a relative M-cone-opic irradiance of at least 0.39.

6. The lighting device as claimed in any one of the previous claims, wherein the lighting device is switchable between the first operation mode and a second operation mode, different from the first operation mode.

7. The lighting device as claimed in claim 6, wherein in the second operation mode the controller is configured to control the one or more light sources to emit lighting device light being white light with a second spectral power distribution, different from the first spectral power distribution, that is optimized for at least one of: energy consumption, CRI, or melanopic equivalent daylight illuminance.

8. The lighting device as claimed in claim 6 or 7, wherein the lighting device is configured to switch from the second operation to the first operation 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 the lighting device; reception of an external switch signal via a communication interface 8 of the lighting device; detection of a speech command by the lighting device; behavioral and / or physiological analysis, by the lighting device, of a user.

9. The lighting device as claimed in claim 6 or 7, wherein the lighting device comprises or is communicatively connected to a sensor, and wherein the lighting device is configured to switch from the second operation to the first operation mode based on data from the sensor.

10. The lighting device as claimed in claim 9, wherein the sensor is selected from the list of a camera configured to capture an image or video stream of the user, a microphone configured to capture a sound produced by the user, and a wearable configured to measure avital sign of the user.

11. The lighting device as claimed in claim 9 or 10, wherein the behavioral and / or physiological analysis by the lighting device is based on data from the sensor comprised in or communicatively connected to the lighting device and results in a signal indicative of a neurological disorder situation or an onset of the neurological disorder, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

12. A method for controlling a lighting device, the lighting device being switchable between a first mode of operation wherein a first lighting device light with a first spectral power distribution is emitted and a second mode of operation wherein a second lighting device light with a second spectral power distribution is emitted, wherein the first lighting device is greenish white light, the greenish white light being white light as defined by ANSI C78.377-2017, and the greenish white light having a relative M-cone-opic irradiance of at least 0.39 and / or at least 2 / 105CCT + 0.3256 and / or at least 3 / 106CCT + 0.4044, the method comprising: receiving one of a signal from a switch operated by the user, a signal indicative of a speech command from the user, and a signal representative of a behavioral and / or physiological condition of a user, the behavioral or physiological condition being indicative of a neurological disorder situation or an onset of the neurological disorder, preferably the neurological disorder comprising at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches; and in response to receiving the signal, causing the lighting device to switch between the first mode of operation and the second mode of operation.

13. The method of claim 12, wherein the signal representative of a behavioral and / or physiological condition of a user is derived from analysis of sensor data from a sensor, the sensor being selected from one or more of a camera configured to capture an image or video stream of the user, a microphone configured to capture a sound produced by the user, and a wearable configured to measure a vital sign of the user.

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