A lighting system configured to provide green and UV-b light

Abstract

A lighting system and device are disclosed that emit specifically designed light to reduce patient discomfort such as migraine pain through the combined use of narrow-band green light and UV-B light. A method using such lighting system or lighting device is also disclosed. The lighting system is configured to provide system light, and comprises a green solid-state light source, an ultraviolet solid-state light source, and a controller. The green solid-state light source emits green light with a first spectral power distribution having a first peak emission wavelength in a first wavelength range of 500–550 nm and a first full-width- half-max FWHM1 of ≤70 nm. The ultraviolet solid-state light source emits ultraviolet light with a second spectral power distribution having a second peak emission wavelength in a second wavelength range of 280–335 nm. The controller is configured to control the green solid-state light source and the ultraviolet solid-state light source.

Description

[0001] 2024PF80118 1

[0002] A LIGHTING SYSTEM CONFIGURED TO PROVIDE GREEN AND UV-B LIGHT

[0003] FIELD OF THE INVENTION

[0004] This disclosure relates to a system, method and device for emitting green and UV-B light, in particular to such system wherein the emitted light is configured for the reduction and treatment of neurological disorders.

[0005] BACKGROUND OF THE INVENTION

[0006] Lighting systems utilizing solid-state light sources, such as LEDs, are widely used for various applications, including general illumination and specialized lighting. Recent advancements have explored the therapeutic potential of light, particularly green light in treating migraine or other neurological disorders such as fibromyalgia, neuropathy, or chronic headaches (see, e.g., Lipton et al., ‘Narrow band green light effects on headache, photophobia, sleep, and anxiety among migraine patients: an open-label study conducted online using daily headache diary’, Frontiers in Neurology 14: 1282236 (2023)). However, existing lighting systems often lack the ability to precisely control the spectral power distribution and intensity of different light components, which is crucial for therapeutic applications.

[0007] Further research indicates that vitamin D can also play a role in mitigating migraine symptoms. A low dietary intake of calcium, magnesium, or a combination of these minerals is associated with an increased occurrence of migraines in women. Conversely, a high calcium intake has been found to potentially protect against migraines in men (see, e.g., Meng et al., ‘Dietary Intake of Calcium and Magnesium in Relation to Severe Headache or Migraine’, Frontiers in Nutrition 8:653765 (2021)).

[0008] In light of the above, there is a need in the art for a method, system and device that can provide controlled light treatment to alleviate symptoms and treat neurological disorders.

[0009] SUMMARY OF THE INVENTION

[0010] To that end, a lighting system and device are disclosed that is configurable to emit specifically designed light to reduce patient discomfort such as migraine pain through the combined use of narrow-band green light and UV-B light. 2024PF80118 2

[0011] In an aspect, the current disclosure relates to a lighting system configured to provide, in operation, system light, the lighting system comprising a green solid-state light source, an ultraviolet solid-state light source, and a controller. The green solid-state light source is configured to emit green light with a first spectral power distribution, the first spectral power distribution having a first peak emission wavelength ( i) in a first wavelength range of 500-550 nm and a first full-width-half-max FWHMi of <70 nm. The ultraviolet solid-state light source is configured to emit ultraviolet light with a second spectral power distribution, the second spectral power distribution having a second peak emission wavelength ( 2) in a second wavelength range of 280-335 nm. The controller is configured to control the green solid-state light source and the ultraviolet solid-state light source. Typically, the controller is configured to individually control the green solid-state light source and the ultraviolet solid-state light source. When in use, the controller may be communicatively connected to the green solid-state light source and to the ultraviolet solid-state light source.

[0012] As used herein, the spectral power distribution defines radiant power emitted by a light source at each wavelength or band of wavelengths in the ultraviolet, visible, and infrared regions of the electromagnetic spectrum, usually expressed in units of Watts per nanometer (W / nm). As used herein, the term “light” refers to electromagnetic radiation in the wavelength range between 100 nm and 1 mm. As used herein, the term “visible light” refers to electromagnetic radiation with a wavelength range between 400-700 nm, which can be perceived by the human eye. Light with wavelengths shorter than 400 nm is classified as ultraviolet (UV) radiation, which is further divided into UV-A (315-400 nm), UV-B (280- 315 nm), and UV-C (100-280 nm) ranges. Conversely, optical radiation with wavelengths longer than 830 nm is known as infrared (IR) radiation and is similarly categorized into IR- A(700-1400 nm), IR-B (1400-3000 nm), and IR-C (3000-1000000 nm) ranges. It is noted that other disclosure may use different definitions. As used herein, in the context of spectral power distributions, a “peak” refers to the specific wavelength at which the power output of a light source reaches a local maximum value. This indicates the dominant wavelength where the light source emits the highest amount of power. As used herein, illuminance or luminous flux per unit area (measured in lux), is a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.

[0013] Research has identified light therapy as a potential non-pharmacological treatment for migraines and other neurological disorders, particularly highlighting the benefits of green light exposure. Thus, the green light emitted by the green solid-state light source is of benefit to users suffering from certain neurological conditions, in particular in acute cases. 2024PF80118 3

[0014] Additionally, there is growing evidence that UV-B light also plays a role in reducing migraine pain. Research suggests that vitamin D, which is produced in the skin through exposure to UV-B light, can alleviate migraine symptoms due to its role in calcium absorption and overall neurological health. Hence, the ultraviolet light emitted by the ultraviolet solid-state light source is similar of benefit to users suffering from certain neurological conditions, in particular by providing a chronic effect.

[0015] By combining both light sources in a single system (e.g., a single lighting device), both long-term and short-term benefits may be combined, increasing the effectiveness in alleviating symptoms of neurological conditions such as migraine. Thus, the combination (which may or may not be simultaneous) of green and UV-B light can significantly reduce symptoms associated with neurological disorders, such as pain caused by migraine attacks, offering a new and effective treatment option for those suffering from different neurological conditions. The controller of the lighting system allows for individual or simultaneous control of the green and UV-B light sources, enabling customized treatment protocols tailored to the needs of the user. This combined approach can provide enhanced benefits for migraine sufferers, offering a more comprehensive strategy for pain management.

[0016] In an embodiment, the first wavelength range of the lighting system is 510- 540 nm, e.g. 515-535 nm. Green light in these wavelength ranges has been shown to be especially effective in reducing symptoms of neurological disorders.

[0017] In an embodiment, the first full-width-half-max FWHMi is <60 nm, <50 nm, <40 nm, <30 nm, <20 nm, or <10 nm. Green light with a narrow spectral distribution, and hence a small FWHMi for the peak in the green wavelength range, tends to be more effective in suppressing or alleviating symptoms than light with a broader spectral distribution, possibly because the light has a lower overall intensity at a similar intensity in the first wavelength range.

[0018] In an embodiment, the second wavelength range is 285-325 nm, 290-325 nm, e.g. 295-320 nm, 300-320 nm or 305-315 nm, and / or the second spectral power distribution has a second full-width-half-max FWHM2 of <50 nm. UV-C light can be harmful, and hence, the ultraviolet light may be generated and / or filtered so as not to comprise large amounts of UV-C light. The same may be true, to a lesser extent for short- wavelength UV-B radiation. An optimal balance between potentially detrimental effects and the beneficial effect of vitamin D production, is generally considered to lie around 311 nm.

[0019] In an embodiment, the lighting system has a green operational mode, wherein at least 90%, such as at least 95%, especially at least 98%, up to essentially 100% of the 2024PF80118 4 system light is the green light (e.g., expressed in radiant flux, typically in Watts), and wherein the green light has a luminous flux of at most 100 Im or an illuminance of at most 100 lux.

[0020] In an embodiment, the intensity of the green light at a low setting is between 4 and 100 lux, and the intensity of the green light at a high setting is at least 250 lux.

[0021] Green light, specifically in the 515-535 nm range, has been shown, in particular, to reduce the severity and frequency of migraine attacks when applied at an intensity between 4 to 100 lux. On the other hand, bright (green) light is more suitable for certain activities, such as reading, which may be activated when the user is not suffering from acute symptoms.

[0022] In an embodiment, the lighting system has an ultraviolet operational mode, wherein at least 90%, such as at least 95%, especially at least 98%, up to essentially 100% of the system light (e.g., expressed in radiant flux) is the ultraviolet light.

[0023] By having a green and / or ultraviolet operational mode, the emitted light can be tailored to the current needs of the user. For example, the green operational mode may be useful during an acute attack, whereas the ultraviolet operational mode may be useful when the user is asleep, or as supplemental light when a user is in a sun-lit room.

[0024] In an embodiment, the lighting system is configured to operate in a mixed operational mode, wherein one or more of the following apply: (i) in a first duration at least 90%, such as at least 95%, especially at least 98%, up to essentially 100% of the system light (e.g., expressed in radiant flux) is the green light having a luminous flux of at most 100 Im or an illuminance of at most 100 lux, optionally followed by an interval of different light or no light, and then a second duration wherein at least 90%, such as at least 95%, especially at least 98%, up to essentially 100% of the system light (e.g., expressed in radiant flux) is the ultraviolet light; (ii) in a first duration at least 90%, such as at least 95%, especially at least 98%, up to essentially 100% of the system light (e.g., expressed in radiant flux) is the ultraviolet light, optionally followed by an interval of different light or no light, and then a second duration wherein at least 90%, such as at least 95%, especially at least 98%, up to essentially 100% of the system light (e.g., expressed in radiant flux) is the green light having a luminous flux of at most 100 Im or an illuminance of at most 100 lux.

[0025] In another embodiment, the lighting system is configured to operate in a mixed operational mode, wherein in the mixed operational mode the system light comprises green light with a luminous flux of at most 100 lux and ultraviolet light with a radiant exposure of at most 30 mW / m2, incorporating both green light and ultraviolet light. This combination ensures the optimal intensity of green light, proven to be effective for therapeutic purposes, 2024PF80118 5 along with a safe exposure level of UV light, maintaining safety while delivering the beneficial effects associated with UV exposure.

[0026] In an embodiment, the controller is further configured to individually control the green solid-state light source and the ultraviolet solid-state light source such that the relative contributions of the green light and the ultraviolet light to the system light is varied. Hence, the controller is enabling individual and combined operation of the green and UV light sources. This allows the system to switch between different operational modes: e.g., the green operational mode, the ultraviolet operational mode, and the mixed operational mode. These distinct operational modes offer flexibility in treatment protocols, allowing for customized light therapy sessions that can address different aspects of neurological disorders, and in particular migraine.

[0027] In an embodiment, the lighting system further comprises a first solid-state white light source, wherein the first solid-state white light source is configured to emit first white light. The first solid-state white light source may comprise a first blue solid-state light source configured to emit first blue light having a third peak emission wavelength ( 3) in a third wavelength range of 400 to 490 nm and a first luminescent element, the first luminescent element comprising a first green luminescent material, the first green luminescent material being configured to at least partly convert the first blue light into first green converted light having a fourth peak emission wavelength ( 4) in a fourth wavelength range of 500 to 580 nm and having a third full-width-half-maximum FWHM3 of >90 nm. The first white light has a first correlated color temperature (CCTi), in a range from 1700 to 6500 K. In such an embodiment, the controller may be further configured to control the first solid-state white light source. The first solid-state white light source may be individually controllable by the controller.

[0028] The presence of a white light source allows to use the same device also for normal (non-therapeutic) lighting, possibly concurrent with the UV-B lighting. A light source with a luminescent element, such as a phosphor-converted light source, provides a broad spectral power distribution (compared to a ‘direct’, or non-phosphor-converted solid-state light source), which is generally more suitable for general purposes (e.g., home or office use) than light with a narrow spectral power distribution. Moreover, phosphor-converted light tends to have a higher color rendering index than (a combination of) direct light sources.

[0029] In an embodiment, the lighting system further comprises a second solid-state white light source, wherein the second solid-state white light source is configured to emit second white light, the second solid-state white light source comprising a second blue solid- 2024PF80118 6 state light source configured to emit second blue light having a fifth peak emission wavelength (Xs) in the third wavelength range of 400 to 490 nm and a second luminescent element, the second luminescent element comprising a second green luminescent material, the second green luminescent material being configured to at least partly convert the blue light into second green converted light having a sixth peak emission wavelength (Xe) in the fourth wavelength range from 500 to 580 nm and having a fourth full-width-half-maximum FWHM4 of >90 nm, wherein the second white light has a second correlated color temperature, CCT2, in the range from 1700 to 6500 K, and wherein | CCT2 - CCTi | > 500 K and wherein the controller is further configured to control the second solid-state white light source. The first solid-state white light source may be individually controllable by the controller.

[0030] The presence of white light sources with different CCTs allows an adjustable CCT. In particular, this allows a so-called dim-to-warm dimming trajectory, which mimics the dimming properties of incandescent bulbs, which may be appreciated by users.

[0031] In an embodiment, the first and / or second green luminescent material comprises a green phosphor. The green phosphor may include one or more of a nitride green phosphor, a P-SiAlON:Eu2+phosphor, and a barium magnesium aluminate green phosphor. The green phosphor has a peak emission wavelength in the 510-540 nm range and can effectively be excited by a 400-460 nm violet or blue LED chip. In another embodiment, the first and / or second green phosphor may comprise a lutetium aluminum garnet (Lu AG) and / or lutetium yttrium aluminum garnet (LuYAG) LED phosphor, which have a dominant emission peak wavelengths ranging from 520 to 540 nm and can be effectively excited by a 450 nm blue LED chip. The phosphor has a full-width-half-max (FWHM) higher than 90 nm, ensuring broad and effective green light emission.

[0032] In an embodiment, an optical filter is used to block or reflect the remaining blue light that has not been converted by the second green luminescent material, ensuring that primarily green light passes through.

[0033] In an embodiment, the second green luminescent material may be identical to the first green luminescent material. If identical, both materials share the same chemical composition, spectral properties, and performance characteristics, ensuring consistent color conversion and uniform light quality, which maintains a consistent spectral power distribution, precise color rendering and uniform illumination. Alternatively, in another embodiment, the second green luminescent material may be different from the first green luminescent material. Using different green luminescent materials allows for optimization of the lighting system for various applications and performance characteristics, such as different 2024PF80118 7 emission peaks, conversion efficiencies, or stability properties. This variability may enhance the lighting system’s ability to cater to different lighting needs and therapeutic requirements, offering personalized solutions while balancing performance, and application-specific demands.

[0034] In an embodiment, CCTi > 3000 K and CCT2 < 2500 K. The first solid-state light source and the second solid-state light source may represent CRI80+ LEDs. In an embodiment the first solid-state light source and the second solid-state light source may represent phosphor-converted white LEDs, combining the benefits of LED technology with the ability to produce high-quality white light suitable for various lighting applications.

[0035] In an embodiment, the lighting system is configured to operate in a white operational mode, wherein the system light comprises at least 80% of the first white light and / or the second white light. In some embodiments, the lighting system may be configured to operate in one or more additional or alternative operational modes, e.g., an operational mode wherein the amount of the ultraviolet light in the system light is dependent on the CCT of the system light and / or on the intensity (as measured in, e.g., Watts or lumens) of the system light. For example, the ultraviolet light may be added or increased when the CCT of the system light is low or decreased; or conversely, the ultraviolet light may be added or increased when the CCT of the system light is high or increased. As a further example, the intensity of the ultraviolet light may increase or decrease with an increase in the intensity of the system light. These operational modes may be selected or adjusted based on the needs of a user. In general, light with a high intensity and a high CCT may resemble sunny daylight, and may therefore be naturally combined with relatively high levels of ultraviolet light. On the other hand, a user dimming the system light (which may be associated with a decrease in CCT) may be indicative of approaching or increasing discomfort of the user, which may motivate an increase in ultraviolet light.

[0036] In an embodiment, the lighting system comprises a content-driven operational mode. In such an operational mode, the spectral power distribution of the system light is determined, at least in part, on media content such as audio content, video content, et cetera.

[0037] In an embodiment, the controller is configured to control the spectral power distribution of the system light in response to a signal, the signal being at least one of:

[0038] — a first signal providing a time of the day and / or a day of the week provided by a clock module;

[0039] — a second signal from a user interface;

[0040] — a third signal from a sensor. 2024PF80118 8

[0041] In particular, the controller may be configured to switch from a general operational mode, e.g., a white-light mode or a content-driven-lighting mode, to a therapeutic operational mode, e.g., the green operational mode, the ultraviolet operational mode, or the mixed operational mode.

[0042] This configuration allows the lighting system to dynamically adjust the spectral power distribution based on various inputs, enhancing user comfort and optimizing lighting conditions. By responding to time-based signals, the system can mimic natural light patterns, promoting better circadian rhythm alignment. Moreover, certain neurological disorders are known to be strongly correlated to, e.g., time of the day, such as morning migraine which is often associated with (early) mornings and in some cases also certain weekdays. User interface signals enable personalized lighting adjustments, catering to individual preferences and needs. Sensor-based signals allow the system to adapt to real-time environmental changes, such as ambient light levels or occupancy, ensuring optimal lighting efficiency and effectiveness throughout different situations. This adaptability makes the lighting system highly versatile and user-friendly, providing a tailored lighting improve the symptoms and provide treatment for certain neurological disorders.

[0043] In an embodiment, the lighting system is configured to operate in a third operation mode wherein the ultraviolet light source is configured to emit light with an intensity that is based on at least one of overall intensity of emitted light, time of day, and sensor data received from a sensor comprised by the lighting system and / or from an external system via a communication interface of the lighting system.

[0044] For example, the lighting system may be configured to provide a higher intensity of UV light when the overall intensity of emitted light is high with the aim to mimic natural daylight. Alternatively or additionally, UV light may only be provided during certain periods of the day or only during the night. Alternatively or additionally, the amount of UV light may be based on sensor data indicating for example a high light intensity (which may be indicative of sunlight coming in through a window filtering out naturally occurring UV light), or indicating little sunshine. In both cases, the system may be configured to compensate for the deficiency in incident UV light.

[0045] In a further aspect, embodiments in this disclosure are related to a controller for a lighting system, e.g., a lighting system as described above. The controller may be communicatively connectable and / or comprised in the lighting system.

[0046] 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 2024PF80118 9 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.

[0047] In an embodiment, the sensor is an optical sensor. In such an embodiment, the controller may control the spectral power distribution of the system light based on an intensity and / or correlated color temperature of ambient light in a room. For example, if the intensity of the ambient light is low, more of the green light may be added. Controlling the spectral power distribution of the system light may comprise switching between operational modes. Furthermore, the lighting system may enhance energy efficiency by adjusting light intensity according to the natural light available, thereby reducing unnecessary energy consumption. It may also improve user comfort and visual clarity by maintaining an optimal correlated color temperature that adapts to different times of day and varying ambient light.

[0048] In an embodiment, the second signal or the third signal is a signal indicative of a neurological disorder situation or an onset of the neurological disorder of a user. The neurological disorder may be one or more of: migraine, fibromyalgia, neuropathy, and chronic headaches.

[0049] In another aspect, the disclosure relates to a lighting device selected from the group of a lamp, a luminaire and a projector device, comprising the lighting system as claimed in any one of the preceding embodiments.

[0050] In another aspect, the disclosure relates to a method for treating a neurological disorder, e.g., at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches. The method comprises: exposing a person who is diagnosed with the neurological disorder to light emitted by a green solid-state light source when the person is suffering or about to suffer from the neurological disorder, the green light source being configured to emit light with a first spectral power distribution, the first spectral power distribution having a first peak emission wavelength ( i) in a first wavelength range of 500-550 nm and a first full-width-half-max FWHMi of <70 nm; and exposing the person to light emitted by an ultraviolet solid-state light source, the ultraviolet light source being configured to emit light with a second spectral power distribution, the second spectral power distribution having a second peak emission wavelength ( 2) in a second wavelength range of 280-335 nm. The person may be exposed to 2024PF80118 10 the ultraviolet light for at least 1 second or at least 1 minute. Additionally or alternatively, the person may be exposed to at least 0.1, 0.3, 0.5, 1, 3, 5, or 10 standard erythema dose (SED) of the ultraviolet light.

[0051] When the person is exposed to the green light, care may be taken not to expose the person to other light, or at least not to other visible light. For example, the person may be exposed to light of the lighting system described above in the green operational mode, typically in an otherwise dark room.

[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. 1A, IB, and 1C schematically illustrate systems and device for emitting green light and ultraviolet light according to embodiments;

[0056] FIG. 2A, 2B, and 2C illustrate the spectral performance of some phosphors according to the embodiments for converting or partially converting blue light to green light;

[0057] FIG. 3 is a flowchart of a method according to an embodiment; and

[0058] FIG. 4 depicts a block diagram illustrating a data processing system as claimed in an embodiment.

[0059] DETAILED DESCRIPTION OF THE DRAWINGS

[0060] In the figures, identical reference numbers indicate identical or similar elements.

[0061] FIG. 1 A schematically illustrates a lighting system 1 configured to provide, in operation, system light, comprising a green solid-state light source 3, an ultraviolet solid-state light source 5 and a controller 11 according to a first embodiment. The controller 11 is configured to control the green solid-state light source and the ultraviolet solid-state light source. The green solid-state light source emits light with a first spectral power distribution having a first peak emission wavelength ( i) in a first wavelength range of 500-550 nm and a 2024PF80118 11 first full-width-half-max FWHMi of <70 nm. The ultraviolet solid-state light source is configured to emit ultraviolet light with a second spectral power distribution, the second spectral power distribution having a second peak emission wavelength ( 2) in a second wavelength range of 280-335 nm. In other embodiments the first wavelength range is 510— 540 nm and the first FWHMi of < 60 nm and the second wavelength range is 290-320 nm and the second power spectral distribution has a second FWHM2 of < 50 nm.

[0062] The controller 11 in the lighting system 1 is responsible for regulating the emission of green and ultraviolet light in different operational modes. For example, in a green operational mode, the controller may ensure that at least 90% of the system’s emitted light is green light, that at least 90% of the system’s emitted visible light is green light, and / or that the green light has a luminous flux not exceeding 100 Im or an illuminance of no more than 100 lux.

[0063] In an ultraviolet operational mode, the controller functions to ensure that at least 90% of the system’s emitted light is ultraviolet light. The controller may be configured to ensure that safety levels are not exceeded. For example, the controller may ensure that the radiant exposure of the ultraviolet light is at most 30 mW / m2The controller may be configured to switch off the ultraviolet light after a predetermined amount of time, which may depend on the (expected) radiant exposure. Thus, the controller may adjust both the intensity and duration of the ultraviolet light emission, ensuring it meets operational specifications and maintains appropriate exposure levels. For example, the intensity may be changed / varied at least 20% and / or the exposure time may be changed / varied at least 20%.

[0064] In a mixed operational mode, the controller manages transitions between green and ultraviolet light, operating in configurations that include alternating periods of green and ultraviolet light or simultaneous combining the two light types. The system light in this mode comprises green light with a luminous flux not exceeding 100 lux and ultraviolet light with a radiant exposure of at most 30 mW / m2The controller ensures that the system light includes both green light and ultraviolet light, allowing the system to adapt to various applications requiring specific light exposure sequences. The controller’s regulation of these transitions ensures the system functions according to defined parameters for each operational mode.

[0065] FIG. IB schematically illustrates a lighting system 1 configured to provide, in operation, system light. The lighting system 1 comprises a green solid-state light source 3, an ultraviolet solid-state light source 5, two additional white light sources 7 and 9 and a controller 11 according to another embodiment of the disclosure. The first solid-state white light source 7 comprises a first blue solid-state light source 13 that emits blue light with a 2024PF80118 12 peak wavelength between 400 and 490 nm. This blue light interacts with a first luminescent element 17 containing a green luminescent material, which converts at least part of the blue light into first green converted light with a peak emission wavelength between 500 and 580 nm and a full-width-half-maximum (FWHM) of at least 90 nm. The first white light has a correlated color temperature (CCTi) ranging from 1700 to 6500 K.

[0066] The second solid-state white light source 9 operates similarly, with a second blue light source 15 that emits light in the 400 to 490 nm range. This blue light is at least partially converted by a second green luminescent element 19 comprising a second luminescent material into green light, producing a second green converted light with a peak emission wavelength between 500 and 580 nm and a FWHM of at least 90 nm. The second white light source has a CCT2 in the range 1700 to 6500 K and differs from the first by at least 500 K. This allows for an adjustable correlated color temperature, e.g., to enable so- called dim-to-warm behavior as is known in the art. For example, the first white light may have a first correlated color temperature CCTi of at least 3000 K and the second white light may have a second correlated color temperature CCT2 of at most 2500 K. The controller 11 is configured to control both the first and second white light sources, adjusting their outputs to achieve the required lighting effects.

[0067] In other embodiments, the lighting system 1 may have only a single white light source. In yet other embodiments, the lighting system 1 may have additional white light sources with different CCTs in the range 1700-6500 K, or even outside that range.

[0068] The presence of the white light sources 7,9 allows the lighting system 1 to operate in a white operational mode, wherein the system light comprises at least 80% of the first white light and (where applicable) the second white light (i.e., the sum of the first and second white light may be at least 80% of the emitted light, as measured in, e.g., radiant power or luminance). The controller functions to ensure that the emitted light maintains this white light composition by adjusting the intensity and duration of the white light emission.

[0069] The luminescent material may comprise a green phosphor and may include one or more of a nitride green phosphor, a P-SiAlON: Eu2+phosphor, and a barium magnesium aluminate green phosphor. Nitride green phosphor can be effectively excited by a 400-460 nm violet or blue LED chip, emitting in the range of 525-545 nm with a full-width-half- maximum (FWHM) of less than 60 nm. P-SiAlON: Eu2+ phosphor has a wide excitation band from 250-460 nm and emits peaks at 535 nm with an FWHM of about 50 nm. Barium magnesium aluminate green phosphor has a peak emission wavelength ranging from 520 nm 2024PF80118 13 to 540 nm, effectively excited by a 450 nm blue LED chip with an FWHM greater than 100 nm. These materials are discussed in more detail below with reference to Fig. 2A-C.

[0070] In the depicted embodiment, the controller 11 coordinates the emissions from the green, UV, and white light sources, ensuring the lighting system functions in different modes, including those where green and UV lights are used simultaneously or alternately. This allows the system to adapt to various applications requiring specific light exposure sequences.

[0071] Additionally, the controller can be configured to control the spectral power distribution of the system light in response to a signal 22, in this example received from a communication interface 21. Examples of such signals are described in more detail below with reference to Fig. 1C.

[0072] Fig. 1C illustrates a schematic of a lighting device that comprises the lighting system described in Fig. 1 A and Fig. IB. The lighting device 2 may be selected from a group of a lamp, a luminaire, and a projector device, and comprises a lighting system 1 as described above with reference to Fig. 1 A and Fig. IB. In the depicted example, the device is equipped with multiple light sources, including green 3, ultraviolet 5, and white light sources 7,9, controlled by an integrated controller 11. The controller allows the lighting device to adapt to various operational modes (e.g., green, ultraviolet, mixed, white, content-driven, et cetera), including the emission of specific light wavelengths and intensities tailored to particular applications, in particular, the treatment of neurological disorders such as migraine, fibromyalgia, neuropathy or chronic headaches.

[0073] The controller 11 may be implemented as a data processing system as described below with reference to Fig. 4. The controller 11 may control the absolute and / or relative output of the one or more light sources 3-9, thereby controlling the spectral power distribution of the emitted system light. Depending on the implementation, the controller 11 may cause the lighting device 2 to switch between the green operation mode, the ultraviolet operation mode, and one or more further operation modes.

[0074] In addition to combining multiple light sources 3-9 , the device is capable of dynamically adjusting its spectral power distribution based on signals 22,24,26,28. Although depicted here as signals that are generated by components 21,23,25,27 of the lighting device 2, in other embodiments, one or more of these components may be external to the lighting device. The controller 11 may activate or deactivate the operational modes and the spectral power distribution in response to an external signal 20 received via a communication interface 21. 2024PF80118 14

[0075] Additionally or alternatively, the controller 11 may activate or deactivate the operational modes and the spectral power distribution in response to a time-based signal 26 from a clock module 25, a user input signal 28 from a (user) interface 27 (e.g., a mechanical switch, or a graphical user interface), or a signal 24 representing environmental data from one or more sensors 23.. For instance, the lighting device 2 can modify its lighting output based on ambient light conditions detected by optical sensors, according to the time of day to mimic natural daylight cycles or to prevent or mitigate regularly occurring symptoms, or the lighting device can respond to user preferences for different activities like reading or working. Additionally, the lighting device can adapt its light to mitigate health conditions, such as adjusting to cooler or dimmer light to help manage and potentially treat symptoms for individuals who experience neurological disorders. This dynamic adjustment ensures the lighting environment is continually optimized for both functional and therapeutic needs.

[0076] Thus, the controller 11 can be configured to control the spectral power distribution of the system light in response to various types of signals.

[0077] The signal can be a first signal 26 providing the time of the day and / or day of the week provided by a clock module 25, allowing the system to adjust lighting patterns according to a pre-set schedule. For instance, the system can emit a different light intensity or color temperature in the morning compared to the evening, aligning with natural circadian rhythms.

[0078] The signal can be a second signal 28 received from a user interface 27, enabling manual adjustments by the user. This allows for real-time customization of the lighting environment based on individual preferences or specific activities, such as reading, working, or relaxing, and / or the onset of presence of discomfort, especially discomfort associated with a neurological disorder.

[0079] The signal can also be a third signal 24 generated by a sensor 23, which might detect ambient light levels, motion, other environmental factors, or the onset / presence of pain as described in more detail in Fig. 1C. For example, the sensor could measure the intensity of natural daylight in a room and adjust the system light accordingly to maintain a consistent lighting level. This capability allows the lighting system to dynamically adjust its output based on temporal settings, user inputs, or environmental feedback, providing a versatile and responsive lighting solution that can cater to various needs and conditions.

[0080] In an embodiment, the sensor 23, is an optical sensor, and the controller 11 controls the spectral power distribution of the system light based on an intensity and / or correlated color temperature of ambient light in a room. This optical sensor can continuously 2024PF80118 15 monitor the ambient lighting conditions, ensuring that the system light complements natural light sources to provide optimal illumination. For example, during daylight hours, if the ambient light is sufficiently bright, the lighting system can reduce its output to conserve energy. Conversely, during cloudy or darker periods, the system can increase its light output to maintain a desired level of brightness. The correlated color temperature (CCT) of the ambient light can also be assessed by the optical sensor, allowing the system to adjust its light color to create a harmonious and comfortable environment. For example, the ultraviolet light may be added or increased when the CCT of the system light is low or decreased; or conversely, the ultraviolet light may be added or increased when the CCT of the system light is high or increased. As a further example, the intensity of the ultraviolet light may increase or decrease with an increase in the intensity of the system light.

[0081] In another embodiment, the second signal 28 or the third signal 24 is a signal indicative of a specific environmental or situational condition. This could include signals related to the presence of individuals in a room, detected via motion sensors, which could prompt the system to switch on or off accordingly or switch between lighting modes (e.g., green, ultraviolet, white or mixed). It might also include signals indicative of a user’s specific health conditions, such as the onset of a migraine, detected through wearable health devices. In such a case, the system could adjust the light output to a setting that comprises green and / or ultraviolet light which has been found to relieve symptoms or treat certain neurological disorders. Moreover, green light has been found to be effective as a short-term remedy for acute migraine attacks, providing immediate relief during these episodes. In contrast, ultraviolet light therapy is more beneficial when used over extended periods, as it helps to reduce the frequency and intensity of migraine attacks. This long-term approach with ultraviolet light aims to lower the overall occurrence and severity of migraines, complementing the immediate alleviation provided by green light.

[0082] These advanced signaling capabilities enable the lighting system 1 to provide highly personalized and adaptive lighting solutions that respond intelligently to a wide range of environmental and user-specific factors, such as signals indicative of a user’s specific health conditions, such as the onset of a migraine, detected through wearable health devices, or adjusting light levels based on circadian rhythms.

[0083] For example the sensor device 23 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, or for emotion recognition (such as pain or 2024PF80118 16 tiredness), et cetera, which may be indicative of the presence or onset of a neurological disorder.

[0084] The sensor device 23 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 29 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.

[0085] The sensor device 23 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.

[0086] In a further example, an additional sensor (e.g., a camera 23) may detect / recognize the onset or presence of a migraine attack or other light-sensitive neurological disorder of the user 29, and cause the controller 11 of the lighting device 2 to pro-actively change the light setting.

[0087] Additionally or alternatively, the controller 11 may activate or deactivate the operation modes in response to a signal received from a (physical) switch provided on the lighting device 2.

[0088] For example, the user 29 can switch between operational modes of the devices and can customize the light intensity, for example using a physical switch, a voice command, a gesture command, et cetera.

[0089] It is noted that the lighting systems depicted in Fig. 1 A and IB may similarly comprise one or more of the signal sources 21-27, and / or be configured to receive a signal from a similar external signal source.

[0090] Fig. 2A is a graph showing the excitation (dashed line) and emission (solid line) spectra of a nitride green LED phosphor. Such a phosphor may be excited by a 400-460 nm violet or blue LED chip, and emits high-purity green light in the 525-545 nm range with a narrow emission spectrum, FWHM <60 nm. These properties make it appropriate for applications such as the neurological disorders treatment device or lighting system in this disclosure, ensuring that the light produced is both effective and consistent in color and intensity.

[0091] Fig. 2B is a graph showing the excitation and emission spectra an oxynitride P- SiAlON: Eu2+phosphor highlighting its suitability for use in the LED lighting device 2024PF80118 17 described in this disclosure. The phosphor’s ability to be excited by blue light (250-460 nm) and emits green light (535 nm) with high color purity (FWHM of about 50 nm), which aligns with the therapeutic goals of the lighting device, making it an effective component for treating neurological disorders such as migraine, fibromyalgia, neuropathy or chronic headaches.

[0092] Fig. 2C demonstrates the excitation and emission properties of Lutetium Aluminum Garnet (LuAG) LED phosphor, highlighting its suitability for use in the lighting system and device described in the current disclosure. The phosphor’s ability to be excited by blue light (450 nm) and emit green light (510-540 nm) with a broad emission spectrum (FWHM > 100 nm) aligns with the therapeutic goals of the device as claimed in an embodiment.

[0093] It should be noted that green light appropriate for the use in different embodiments of the invention may be obtained either using a direct-emitting green LED or by a phosphor converted green LED, for example based on a blue LED with a green luminescent material that may fully convert the blue light emitted by the blue LED into green light. The green luminescent material may preferably be narrow band green phosphor.

[0094] Fig. 3 is a flowchart of a method according to an embodiment. More in particular, Fig. 3 shows a method for controlling a lighting device or lighting system that is configured to emit green light and ultraviolet light as described herein. In some embodiments, the lighting device or lighting system may be switchable between a first mode of operation wherein a first light with a first spectral power distribution is emitted (e.g., green light and / or ultraviolet light) and a second mode of operation wherein a second light with a second spectral power distribution is emitted (e.g., white light or content-driven light). For example, the method may be performed by a lighting system as described above, with reference to Fig. 1 A and IB, or a lighting device as described with reference to Fig. 1C.

[0095] An optional step 30 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, e.g., at least one of: migraine, fibromyalgia, neuropathy, or chronic headaches.

[0096] A step 32 comprises exposing the user (typically a user who is diagnosed with the neurological disorder) to light emitted by a green solid-state light source when the user is suffering or about to suffer from the neurological disorder. The green light source is configured to emit green light with a spectral power distribution having a first peak emission wavelength ( i) in a first wavelength range of 500-550 nm and a first full-width-half-max FWHM of <70 nm. 2024PF80118 18

[0097] A step 34 comprises exposing the user to light emitted by an ultraviolet solid- state light source for at least 1 second or at least 1 minute. The ultraviolet light source is configured to emit ultraviolet light with a spectral power distribution having a second peak emission wavelength ( 2) in a second wavelength range of 280-335 nm.

[0098] Steps 32 and 34 may be performed in any order, including concurrently or partially concurrently, alternating, or in other combinations. In embodiments comprising step 30, step 32 and / or step 34 may comprise, in response to receiving the signal representative of the behavioral and / or physiological condition of the user, causing the lighting device to switch from the second mode of operation to the respective first mode of operation. In particular, the lighting device may switch to a mode of operation wherein the lighting device emits green light as defined herein in response to receiving a signal representative of the presence or onset of the neurological disorder.

[0099] Fig. 4 depicts a block diagram illustrating a data processing system as claimed in an embodiment.

[0100] As shown in Fig. 4, 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.

[0101] 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.

[0102] Input / output (VO) 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- 2024PF80118 19 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.

[0103] In an embodiment, the input and the output devices may be implemented as a combined input / output device (illustrated in Fig. 4 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.

[0104] 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.

[0105] As pictured in Fig. 4, 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. 4) 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.

[0106] In one aspect of the present invention, the data processing system 100 may represent a control system of a LED driver as described herein.

[0107] 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. 2024PF80118 20

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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 2024PF80118 21 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

1. 2024PF80118 22CLAIMS1. A lighting system (1) configured to provide, in operation, system light, the lighting system (1) comprising a green solid-state light source (3), an ultraviolet solid-state light source (5), and a controller (11), the green solid-state light source (3) being configured to emit green light with a first spectral power distribution, the first spectral power distribution having a first peak emission wavelength ( i) in a first wavelength range of 500-550 nm and a first full-widthhalf-max FWHMi of <70 nm, the ultraviolet solid-state light source (5) being configured to emit ultraviolet light with a second spectral power distribution, the second spectral power distribution having a second peak emission wavelength ( 2) in a second wavelength range of 280-335 nm, and the controller (11) being configured to control the green solid-state light source and the ultraviolet solid-state light source, and wherein in a green operational mode at least 90% of the system light is the green light, and wherein the green light has a luminous flux of at most 100 Im or an illuminance of at most 100 lux..

2. The lighting system (1) as claimed in claim 1, wherein the first wavelength range is 510-540 nm and the first full-width-half-max FWHMi is <60 nm.

3. The lighting system (1) as claimed in claim 1 or 2, wherein the second wavelength range is 290-320 nm and the second spectral power distribution has a second full- width-half-max FWHM2 of <50 nm.

4. The lighting system (1) according to any one of the preceding claims, wherein in an ultraviolet operational mode at least 90% of the system light is the ultraviolet light.

5. The lighting system (1) according to any one of the claims 1 to 3, wherein in a mixed operational mode one of the following applies:2024PF80118 23(i) in a first duration at least 90% of the system light is the green light having a luminous flux of at most 100 Im or an illuminance of at most 100 lux, followed by a second duration wherein at least 90% of the system light is the ultraviolet light,(ii) in a first duration at least 90% of the system light is the ultraviolet light followed by a second duration wherein at least 90% of the system light is the green light having a luminous flux of at most 100 Im or an illuminance of at most 100 lux.

6. The lighting system (1) according to any one of the claims 1 to 3, wherein in a mixed operational mode the system light comprises the green light having a luminous flux of at most 100 lux and ultraviolet light having a radiant exposure of at most 30 mW / m2, and wherein the system light comprises both green light and ultraviolet light.

7. The lighting system (1) according to any one of the preceding claims, wherein the controller (11) is further configured to individually control the green solid-state light source (3) and the ultraviolet solid-state light source (5) such that the relative contributions of the green light and the ultraviolet light to the system light is varied.

8. The lighting system (1) as claimed in any one of the previous claims, further comprising a first solid-state white light source (7), wherein the first solid-state white light source (7) is configured to emit first white light, the first solid-state white light source (7) comprising a first blue solid-state light source (13) configured to emit first blue light having a third peak emission wavelength ( 3) in a third wavelength range of 400 to 490 nm and a first luminescent element (17), the first luminescent element (17) comprising a first green luminescent material , the first green luminescent material being configured to at least partly convert the first blue light into first green converted light having a fourth peak emission wavelength ( 4) in a fourth wavelength range of 500 to 580 nm and having a third full-width-half-maximum FWHM3 of >90 nm, wherein the first white light has a first correlated color temperature, CCTi, in a range from 1700 to 6500 K; and wherein the controller (11) is further configured to control the first solid-state white light source.

9. The lighting system (1) as claimed in claim 8, further comprising a second solid-state white light source (9),2024PF80118 24 wherein the second solid-state white light source (9) is configured to emit second white light, the second solid-state white light source (9) comprising a second blue solid-state light source (15) configured to emit second blue light having a fifth peak emission wavelength (Xs) in the third wavelength range of 400 to 490 nm and a second luminescent element (19), the second luminescent element (19) comprising a second green luminescent material, the second green luminescent material being configured to at least partly convert the blue light into second green converted light having a sixth peak emission wavelength (Xe) in the fourth wavelength range from 500 to 580 nm and having a fourth full-width-half- maximum FWHM4 of >90 nm, wherein the second white light has a second correlated color temperature, CCT2, in the range from 1700 to 6500 K, and wherein |CCT2— CCT > 500 K; wherein the controller (11) is further configured to control the second solid- state white light source; and wherein in a white operational mode at least 80% of the system light comprises the first white light and / or the second white light.

10. The lighting system (1) as claimed in any one of the preceding claims, wherein the first and / or second green luminescent material comprises a green phosphor selected from the group of a nitride green phosphor, a P-SiAlON:Eu2+phosphor, a barium magnesium aluminate green phosphor, a lutetium aluminum garnet (Lu AG) and / or lutetium yttrium aluminum garnet (LuYAG) phosphor.

11. The lighting system (1) as claimed in any one of the preceding claims, wherein the controller is configured to control the spectral power distribution of the system light in response to a signal, the signal being at least one of— a first signal (26) providing a time of the day and / or a day of the week provided by a clock module (25);— a second signal (28) from a user interface (27);— a third signal (24) from a sensor (23).

12. The lighting system (1) according to claim 11 wherein the sensor is an optical sensor, and wherein the controller (11) controls the spectral power distribution of the system light based on an intensity and / or correlated color temperature of ambient light in a room.2024PF80118 2513. The lighting system (1) as claimed in claim 11 or 12, wherein the second signal(28) or the third signal (24) is a signal indicative of a neurological disorder situation or an onset of the neurological disorder of a user.

14. A lighting device (2) selected from the group of a lamp, a luminaire and a projector device, comprising the lighting system (1) as claimed in any one of the preceding claims.

15. 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 (32) a person (29) who is diagnosed with the neurological disorder to light emitted by a green solid-state light source (3) when the person is suffering or about to suffer from the neurological disorder, the green light source being configured to emit light with a first spectral power distribution, the first spectral power distribution having a first peak emission wavelength ( i) in a first wavelength range of 500-550 nm and a first full-widthhalf-max FWHMi of <70 nm; and exposing (34) the person (29) to light emitted by an ultraviolet solid-state light source (5) for at least 1 second or at least 1 minute, the ultraviolet light source being configured to emit light with a second spectral power distribution, the second spectral power distribution having a second peak emission wavelength ( 2) in a second wavelength range of 280-335 nm.

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