WO2020212325A1

WO2020212325A1 - Cytochrome c oxidase activating lighting system for mitochondrial activation and ocular health

Info

Publication number: WO2020212325A1
Application number: PCT/EP2020/060422
Authority: WO
Inventors: Rémy Cyrille BROERSMA; Martinus Petrus Joseph PEETERS; Lucas Josef Maria Schlangen
Original assignee: Signify Holding B.V.
Priority date: 2019-04-15
Filing date: 2020-04-14
Publication date: 2020-10-22

Abstract

The invention provides a lighting system (1000) comprising (i) one or more solid state light sources (10) configured to generate light source light (11) and optionally (ii) one or more luminescent materials (20) configured to convert at least part of the light source light (11) into luminescent material light (21), wherein the lighting system (1000) is configured to generate in an operation mode lighting system light (1001) comprising one or 5 more of the light source light (11) and the optional luminescent material light (21), wherein the one or more solid state light sources (10) and the optional one or more luminescent materials (20) are selected and/or controlled to provide in the operation mode a selectable and/or controllable amount of red, deep red or near infrared light in the lighting system light (1001) with the condition that (a) the lighting system light (1001) is white light, and (b) the 10 lighting system light (1001) has a minimum efficacy in activating cytochrome C oxidase in human tissue.

Description

Cytochrome C oxidase activating lighting system for mitochondrial activation and ocular health

FIELD OF THE INVENTION

The invention relates to a lighting system and to a method of controlling a lighting system.

BACKGROUND OF THE INVENTION

There is a desire in the art for improving the luminous efficacy of a lighting system. US6234648B1, for instance, describes a lighting system comprising at least two light-emitting diodes, each of said at least two light-emitting diodes emitting, in operation, visible light in a preselected wavelength range, and conversion means for converting a part of the visible light emitted by one of the at least two light-emitting diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system; wherein the at least two light-emitting diodes comprise at least a blue light-emitting diode and at least a red light-emitting diode; and wherein the conversion means include a luminescent material for converting a portion of the light emitted by the blue light-emitting diode into green light. This document also describes a further improvement of the color rendering index Ra achieved by not only employing red and blue LEDs as sources of primary light but, for example, a combination of 4 different LEDs. A particularly suitable lighting system disclosed comprises: blue GaN LEDs (make Nichia): emission maximum: 470 nm, FWHM=20 nm; blue-green GaN LEDs (make Nichia): emission maximum: 520 nm, FWHM=40 nm; yellow GaP LEDs (make Hewlett Packard): emission maximum: 590 nm, FWHM=20 nm; red GaP LEDs (make Hewlett Packard): emission maximum: 620 nm, FWHM=20 nm; and conversion means comprising a layer of Ba₂Si0₄:Eu²⁺. Such a lighting system has a luminous efficacy beyond 20 lm/W. For comparison, a typical 100 W incandescent lamp has a luminous efficacy of 14 lm/W (color temperature 2800 K, color rendering index 100), a 500 W halogen incandescent lamp has a luminous efficacy of approximately 19 lm/W (color temperature 3000 K, color rendering index 100), while a 36 W fluorescent lamp has a luminous efficacy of approximately 90 lm/W (color temperature 4000 K, color rendering index 85). A further improvement of the color rendition of the lighting system is achieved by employing deep red LEDs with a spectral emission maximum in the wavelength range from 620 to 670 nm. A color rendering index of the disclosed lighting system may be at least equal to or greater than 80.

US 2017/086274 A1 discloses systems and methods for improving color accuracy and uniformity in LED illumination systems, including light engines, switching circuits and methods of adding phosphors or lumiphoric materials for controlling the addition or subtraction of light from one or more color light sources of the light engines to produce light of a uniform and consistent color. Systems and methods of providing LED light engines and associated illumination spectrums that are both visually appealing, rich in melanopic flux and that reduce blue light hazard exposure are also disclosed.

SUMMARY OF THE INVENTION

Elderly people may suffer from eye related health issues, like age-related macular degeneration (AMD), glaucoma, etc... As people are getting older and trends indicating that people have to work longer before retirement, eye health related problems may occur more frequently and pose more inconvenience than before. One of the assumed mechanisms contributing to these age-related ocular pathologies is the cumulative exposure over the lifetime to high energetic light that compromises mitochondrial activity in the eye.

Studies with deep red and NIR light have shown that the mitochondrial activity can be improved in ocular tissues of animals, indicating that visual -function and eye- health related problems like AMD and glaucoma, can be improved. The mitochondrial activation can be realized by the chromophore Cytochrome C oxidase in the mitochondria that absorb deep red/NIR light and stimulates amongst others the production of ATP, the primary source of energy for cells.

M. Fitzgerald et al. describe in“Red/near-infrared irradiation therapy for treatment of central nervous system injuries and disorders”, Rev. Neurosci. 2013;24(2):205- 26. doi: 10.1515/revneuro-2012-0086, amongst others that there is“strong evidence that 670- nm irradiation gives significant protection to the retina, and some studies indicate that cytochrome c oxidase is the most likely photoreceptor”. There may be a desire to provide solutions that can prevent or reduce the necessity of e.g. ophthalmic phototherapy.

Ophthalmic phototherapy also inherently implies a treatment, as it is a therapy, and therefore impacts on one’s life.

The content of deep red and NIR light in the current electrical light sources for general illumination, especially in fluorescent and LED light sources, is minimal. This may be due to an ever increasing desire to maximize luminous efficacy. Hence, it is an object of the invention to provide an alternative lighting system or lighting device which, at least partly, may contribute to preventing or reducing eye related health issues. Further, it is an object of the invention to provide an alternative solution for ophthalmic phototherapy to address eye related health concerns. The present invention may have as a further object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

In an aspect, the invention provides a lighting system comprising one or more solid state light sources configured to generate light source light. In specific examples the lighting system may further (optionally) comprise one or more luminescent materials configured to convert at least part of the light source light into luminescent material light. Especially, the lighting system is configured to generate lighting system light. In specific examples, the lighting system is configured to generate in an operation mode lighting system light comprising one or more of the light source light and the optional luminescent material light. Even more specifically, the one or more solid state light sources and the optional one or more luminescent materials may be selected and/or controlled to provide in the operation mode the lighting system light with a selectable and/or controllable amount of red, deep red or near infrared light with the condition of the lighting system light being white light, in specific embodiments characterized by a color point within 10 SDCM (standard deviation of color matching), more especially within 7 SDCM, from the Black Body Line (BBL).

Alternatively or additionally, the one or more solid state light sources and the optional one or more luminescent materials may be selected to provide the lighting system light in the operation mode with the condition of the lighting system light having a luminous efficacy of at least 40 lm/W (i.e. 40 lumen per Watt). Alternatively or additionally, the one or more solid state light sources and the optional one or more luminescent materials may be selected to provide the lighting system light in the operation mode with the condition of the lighting system light having a cytochrome C oxidase efficacy of radiation (also referred to as CC eff) complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis (herein also indicated as“CC eff DNA”) is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis (herein also indicated as“CC_eff RNA”) is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm. Especially, the cytochrome C oxidase efficacy may be defined as:

wherein: _b,lO'O ⁼ is the spectral power distribution of the lighting system light; s_cyt(X) = is the spectral sensitivity of cytochrome C oxidase activation for either DNA synthesis or RNA synthesis; V(X) = is the photopic luminosity function; and v’ is a color coordinate of the lighting system light in the CIE 1976 UCS (uniform chromaticity scale) diagram.

Hence, especially the invention provides (in an aspect) a lighting system comprising (i) one or more solid state light sources configured to generate light source light and optionally (ii) one or more luminescent materials configured to convert at least part of the light source light into luminescent material light, wherein the lighting system is configured to generate in an operation mode lighting system light comprising one or more of the light source light and the optional luminescent material light, wherein the one or more solid state light sources and the optional one or more luminescent materials are selected and/or controlled to provide in the operation mode the lighting system light with a selectable and/or controllable amount of red, deep red or near infrared light with the following conditions: (a) the lighting system light is white light, especially characterized by a color point within 10 SDCM from the Black Body Line, more especially within 7 SDCM; and (b) the lighting system light has a cytochrome C oxidase efficacy of radiation complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm, wherein the cytochrome C oxidase efficacy is defined as (above).

With such lighting system, it is possible to generate white light with a relative high color rendering index and with wavelengths that may be beneficial to the eyes e.g. the eye health.

In a preferred embodiment the one or more solid state light sources and the optional one or more luminescent materials are selected to provide the lighting system light in the operation mode with a luminous efficacy of at least 40 lm/W. In this preferred embodiment, the lighting system can generate white light with a relatively high luminous efficacy. Hence, though the luminous efficacy may be slightly lower than achievable for other white light having the same color point and about the same color rendering index, the light according to the invention may aid in preventing or curing eye related health issues, like age-related macular degeneration (AMD), glaucoma, etc. Further, in embodiments such system may also be adapted to vary the radiation in dependence of features like the blue content, the correlated color temperature, the time of the day, the intensity of the lighting system light, etc. As indicated above, the lighting system may comprise (i) one or more solid state light sources configured to generate light source light and optionally (ii) one or more luminescent materials configured to convert at least part of the light source light into luminescent material light. Hence, the lighting system light may comprise one or more of the light source light and the optional luminescent material light. Especially, the lighting system light may comprise a contributions in the red, especially the deep red, which is relevant for the cytochrome C oxidase and such contributions may be individually controlled. Hence, in embodiments there are at least two solid state light sources, of which one or more may generate, optionally together with one or more luminescent materials, light having one or more wavelengths in one or more of the blue, green, yellow, and optionally red, spectral region, and of which one or more may generate, optionally together with one or more luminescent materials, light having one or more wavelengths in the red. Hence, in

embodiments the lighting system may comprise two or more solid state light sources. Phrases like“one or more solid state light sources” or“two or more solid state light sources” and similar phrases, may especially refer to one or more different types of solid state light sources” or“two or more different types of solid state light sources”. Further embodiments are described below. As indicated below, the term“red” herein especially includes red, deep red and near infrared (i.e. about 620-1400 nm).

The term“light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term“light source” may also refer to an organic light-emitting diode, such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid state light source (such as a LED or laser diode). In an embodiment, the light source comprises a LED (light emitting diode). The term LED may also refer to a plurality of LEDs. Further, the term“light source” may in embodiments also refer to a so-called chips-on-board (COB) light source. The term“COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of semiconductor light sources may be configured on the same substrate.

In embodiments, a COB is a multi LED chip configured together as a single lighting module. The term“light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 solid state light sources. Hence, in embodiments the term“one or more solid state light sources” may also refer to a COB. In embodiments, the light source may comprise one or more micro-optical elements (array of micro lenses) downstream of a single solid state light source, such as a LED, or downstream of a plurality of solid state light sources (i.e. e.g. shared by multiple LEDs). In embodiments, the light source may comprise a LED with on-chip optics. In embodiments, the light source comprises a pixelated single LEDs (with or without optics) (offering in embodiments on-chip beam steering).

The phrases“different light sources” or“a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid state light sources selected from at least two different bins. Likewise, the phrases“identical light sources” or“a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid state light sources selected from the same bin. The terms“different light sources” or especially“different types of light sources” may refer to light sources configured to generate light source light having different spectral distributions.

The term“luminescent material” especially refers to a material that can convert radiation into light, especially one or more of UV radiation and blue radiation, into visible light. The luminescent material may in specific embodiments also convert radiation into infrared radiation (IR). Hemce, upon excitation with radiation, the luminescent material emits radiation. In general, the luminescent material will be a down converter, i.e. radiation of a smaller/shorter wavelength is converted into radiation with a larger/longer wavelength (k_ex< _em), though in specific embodiments the luminescent material may comprise upconverting luminescent material, i.e. radiation of a larger/longer wavelength is converted into radiation with a smaller/shorter wavelength ( _ex> _em). In embodiment, the term “luminescence” may refer to phosphorescene. In embodiments, the term“luminescence” may also refer to fluorescence. The term“luminescent material” may also refer to a plurality of different luminescent materials. The term“different light luminescent materials” may refer to luminescent materials configured to generate luminescent material light, respectively, having different spectral distributions.

In embodiments, luminescent materials are selected from garnets and nitrides, especially doped with trivalent cerium or divalent europium, respectively. Embodiments of garnets especially include A3B5O12 garnets, wherein A comprises at least yttrium or lutetium and wherein B comprises at least aluminum. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B comprises aluminum (Al), however, B may also partly comprise gallium (Ga) and/or scandium (Sc) and/or indium (In), especially up to about 20% of Al, more especially up to about 10 % of A1 (i.e. the B ions essentially consist of 90 or more mole % of A1 and 10 or less mole % of one or more of Ga, Sc and In); B may especially comprise up to about 10% gallium. In another variant, B and O may at least partly be replaced by Si and N. The element A may especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and/or Tb are especially only present up to an amount of about 20% of A. In a specific embodiment, the garnet luminescent material comprises (Yi-_xLu_x)3B50i2:Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1.

The term“:Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the“A” ions) in the luminescent material is replaced by Ce. For instance, in the case of (Yi- _xLu_x)₃Al₅0i₂:Ce, part of Y and/or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will replace A in general for not more than 10%; in general, the Ce concentration will be in the range of 0.1 to 4%, especially 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the full correct formula could be (Yo_.iLuo_.89Ceo_.oi)3Al50i2.

Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art.

In embodiments, a red luminescent material may comprise one or more materials selected from the group consisting of (Ba,Sr,Ca)S:Eu, (Ba,Sr,Ca)AlSiN3:Eu and (Ba,Sr,Ca)2Si5N8:Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation; its presence will especially be in the range of about 0.5 to 10%, more especially in the range of about 0.5 to 5% relative to the cation(s) it replaces. The term“:Eu”, indicates that part of the metal ions is replaced by Eu (in these examples by Eu²⁺). For instance, assuming 2% Eu in CaAlSiN3:Eu, the correct formula could be (Cao_.98Euo_.o₂)AlSiN₃. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba.

The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca).

Further, the material (Ba,Sr,Ca)2Si Nx:Eu can also be indicated as iVLSLNsiEu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and/or Ba. In a further specific embodiment, M consists of Sr and/or Ba (not taking into account the presence of Eu), especially 50 to 100%, more especially 50 to 90% Ba and 50 to 0%, especially 50 to 10% Sr, such as Bai_.sSro_.sSENsiEu (i.e. 75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca).

Likewise, the material (Ba,Sr,Ca)AlSiN3:Eu can also be indicated as

MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca).

The term“luminescent material” herein especially relates to inorganic luminescent materials, which are also sometimes indicated as phosphors. These terms are known to the person skilled in the art.

Alternatively or additionally, also other luminescent materials may be applied. For instance quantum dots and/or organic dyes may be applied and may optionally be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc. etc...

Quantum dots are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots. Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium free quantum dots such as indium phosphide (InP), and copper indium sulfide (CuInS ) and/or silver indium sulfide (AglnS ) can also be used. Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore the emission color can easily be tuned by adapting the size of the quantum dots. Any type of quantum dot known in the art may be used in the present invention. However, it may be preferred for reasons of environmental safety and concern to use cadmium-free quantum dots or at least quantum dots having a very low cadmium content.

Instead of quantum dots or in addition to quantum dots, also other quantum confinement structures may be used. The term“quantum confinement structures” should, in the context of the present application, be understood as e.g. quantum wells, quantum dots, quantum rods, tripods, tetrapods, or nano-wires, etcetera.

Organic phosphors can be used as well. Examples of suitable organic phosphor materials are organic luminescent materials based on perylene derivatives, for example compounds sold under the name Lumogen® by BASF. Examples of suitable compounds include, but are not limited to, Lumogen® Red F305, Lumogen® Orange F240, Lumogen® Yellow F083, and Lumogen® F170.

The luminescent material may also comprise a Mn⁴⁺ based luminescent material. This will be elucidated below.

As indicated above, in an operation mode the lighting system light may comprise one or more of the light source light and the optional luminescent material 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. measuring, displaying, actuating, opening, shifting, changing temperature, etc... Beyond that, the term“controlling”, and similar terms may additionally include monitoring. Hence, the term“controlling”, and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as“controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and/or wireless control. The term“control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface.

The term "controllable" in the context of lighting systems or light sources especially refers to the ability to control a light source of a lighting system to emitted light source light having a particular optical property value. A controllable optical property especially refer to the possibility that a plurality of values, especially more than two, can be chosen for the respective optical property. Hence, with reference to intensity, "controllable" may imply a plurality of different intensity values between off and maximum power. With reference to color point, "controllable" may imply the possibility of selecting a plurality of different v’ values (in the CIE 1976 color space). Hence, one or more optical properties, including spectral properties such as the spectral power distribution, of the light are controllable. The term“controlling” in the context of optical properties then refers to controlling the value of the particular optical property. The control system may also be configured to receive and execute instructions from a remote control device. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or iPhone, a tablet, etc. Such device is thus not necessarily coupled to the lighting system but may be (temporarily) functionally coupled to the lighting system.

Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. In such embodiments the control system of the lighting system may be a slave control system or adapted to control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control device which has access to the lighting system on the basis of knowledge of the (unique) code of the lighting system, for example provided via a user interface or via an optical sensor (e.g. QR code reader). The lighting system may also comprise means for communicating with other systems or devices, such as remote control devices, on the basis of for example Bluetooth, Wi-Fi, ZigBee, BLE or WiMAX, or another wireless technology.

The system, or apparatus, or device may execute an action in a“mode” or “operation mode” or“mode of operation”. Likewise, in a method an action or stage, or step may be executed in a“mode” or“operation mode” or“mode of operation”. The term“mode” may also be indicated as“operation mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another operation mode, or a plurality of other operation modes. Likewise, this may not exclude that before executing the mode and/or after executing the mode one or more other modes may be executed.

However, in embodiments a control system may be available, that is adapted to provide at least one operation mode of the lighting system. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to the operation mode of a system, or apparatus, or device, that can only operate in a single operation mode (i.e.“on”, without further tunability).

As indicated above, the one or more solid state light sources and the optional one or more luminescent materials are selected to provide the lighting system light in the operation mode with the lighting system light meeting one or more specific conditions. As elucidated above, in specific embodiments the spectral properties of the lighting system light, including the cytochrome C oxidase efficacy, may essentially be fixed. However, in other embodiments the spectral properties of the lighting system light, including the cytochrome C oxidase efficacy, may be controllable. Especially, in such embodiments the system may further comprise a control system to control the lighting system light. Further embodiment will be elucidated below.

Especially, the phrase indicating that the one or more solid state light sources and the optional one or more luminescent materials are selected to provide the lighting system light in the operation mode with one or more properties and similar phrases may indicate that the combination of light source(s) and optional luminescent materials are selected and/or controlled such that the lighting system light has the indicated one or more properties. These properties may in embodiments be obtained by selecting light source(s) and/or luminescent material(s), in the case of a system wherein the optical properties of the lighting system light may essentially not be controllable, or may in other embodiments be obtained by controlling light sources(s) and/or luminescent material(s). When the lighting system provides lighting system light of which the optical properties are controllable, there may also be more operation modes wherein the herein indicated conditions are achieved. Hence, the term“operation mode” may also refer to a plurality of different operation modes.

The lighting system light may be provided (in the controlling mode) meeting one or more of the conditions: (a) the lighting system light is white light characterized by a color point within 10 SDCM from the Black Body Line; (b) the lighting system light has a luminous efficacy of at least 40 lm/W ; (c) the lighting system light has a cytochrome C oxidase efficacy of radiation complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm.

Hence, in embodiments the lighting system light may be provided (in the controlling mode) as white lighting system light, especially characterized by a color point within 10 SDCM from the Black Body Line (or black body locus). The term“white light” herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 1800 K, such as about 2000 K, and 20000 K, especially between 2700 K and 20000 K, for general lighting especially in the range of about 2700 K and 6500 K, and for backlighting purposes especially in the range of about 7000 K and 20000 K, and especially within about 10 SDCM from the BBL, more especially within about 7 SDCM from the BBL, even more especially within about 5 SDCM from the BBL. The closer the color point is to the BBL, the less off-white the white light is.

Also, in embodiments the lighting system light may be provided having a photopic luminous efficacy of at least 40 lm/W. Here, the term“photopic luminous efficacy”, “luminous efficacy” or“efficacy” especially refers to the photopic luminous efficacy of radiation, which has a maximum possible value of 683 lm/W (lumen per watt ), for the case of monochromatic light at a wavelength of 555 nm (green). For instance, a tungsten light bulb at about 2800 K has a luminous efficacy of about 15 lm/W. The lighting system of the present invention has a substantial higher luminous efficacy than a tungsten light bulb. For instance, this may be achieved with one or more primarily blue emitters, one or more primarily green and/or yellow emitters, and one or more primarily red emitters. The luminous efficacy is related to the spectral eye sensitivity (V (2)), which is at maximum at about 555 nm, and which rapidly decreases below about 500 nm or above about 630 nm, and is hardly significant anymore at wavelengths below about 450 nm or above about 680 nm. Photopic luminous efficacies of at least 40 lm/W may be achieved when using e.g. the one or more solid state light sources (and the optionally one or more luminescent materials) as described herein.

The activation spectrum for the cytochrome C oxidase chromophore appears to differ for DNA synthesis and RNA synthesis. The activation spectra are known in the art and are herein illustrated as graphs (Fig. 1) and in table format (Table 1) to be used in numerical integration methods to approximate the value of the integral in cytochrome C oxidase efficacy formula:

Table 1 : activation spectra (s_cyt(X)) for the cytochrome C oxidase chromophore for

DNA and RNA synthesis, respectively

The spectral sensitivity data of cytochrome C oxidase activation as listed in Table 1 and illustrated in Fig. 1 are normalized to 1. Note that the most pronounced and efficient activation is in the wavelength range between 550-900 nm. For wavelengths which activate cytochrome C oxidase, i.e. within a range from 550 nm to 900 nm, a cytochrome C oxidase efficacy can be defined, semi analogous to the photopic luminous efficacy for visible light but now in relation to cytochrome C oxidase activation instead of photopic luminosity. Such efficacy is referred to herein as cytochrome C oxidase efficacy (CC eff) of light. Such efficacy may be defined as the spectral power of the light in the spectral range of 550-900 nm weighted with the cytochrome C oxidase activation curves for respectively DNA synthesis and RNA synthesis, respectively, relative to the spectral power in the spectral range of 380- 780 nm weighted with the luminosity function of the human eye.

These cytochrome C oxidase efficacy thus also differs for DNA and RNA synthesis, which is the reason why the cytochrome C oxidase efficacy related feature of the herein described lighting devices and systems is defined for DNA and RNA synthesis respectively. The cytochrome C oxidase efficacy is in general defined as:

J_ss„ _¾*a) M

Cytochrome C oxidase Efficacy of radiation (W / Lm ) = 7RO

683 J₃₈₀ F_eL U) V( ) άl wherein:

b_,lO'O ⁼ is the spectral power distribution of the lighting system light;

s_cyt(A) = is the spectral sensitivity of cytochrome C oxidase activation for either DNA synthesis or RNA synthesis;

V(X) = is the photopic luminosity function; and

v’ is a color coordinate of the lighting system light in the CIE 1976 UCS (uniform chromaticity scale) diagram.

The inventors have extensively studied existing commercially available lamps providing white light, but to the best of their knowledge none of the existing lamps provide white light (especially with a color point within 10 SDCM, especially within 7 SDCM, from the Black Body Line and/or especially having an photopic luminous efficacy of at least 40 lm/W) having a cytochrome C oxidase efficacy complying with the condition (i) that the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and/or with the condition (ii) that the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm. The luminous efficacy of known ((amongst others) solid state based) examples having a correlated color temperature between 2700-6300 K is found to be in the range of 21.5-23.4 lm/W.

Above cytochrome C oxidase efficacy conditions imply four alternative conditions of which, in embodiments, two or more may be combined.

Especially, in embodiments (in an operation mode) the lighting system light may comply with following conditions: the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm. In other embodiments, the lighting system light may comply with at least the smaller value of at least (6.2*v’-2.48) mW/lm and at least 0.85 mW/lm. In still other embodiments, the lighting system light may comply with the larger value of at least (6.2*v’-2.48) mW/lm and at least 0.85 mW/lm. Especially, in embodiments the cytochrome C oxidase efficacy for DNA synthesis of the lighting system light is at least 0.4 mW/lm, especially at least 0.45 mW/lm, for all v’ values smaller than 0.45 (and of course within 10 SDCM, more especially within 7 SDCM from the Black Body Line).

Alternatively or additionally, in embodiments (in an operation mode) the lighting system light may compy with following conditions: the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm. In other embodiments, the lighting system light may comply with at least the smaller value of at least (7.5*v’-2.975) mW/lm and at least 1.05 mW/lm. In still other embodiments, the lighting system light may comply with the larger value of at least (7.5*v’-2.975) mW/lm and at least 1.05 mW/lm. Especially, in embodiments the cytochrome C oxidase efficacy for RNA synthesis of the lighting system light is at least 0.45 mW/lm, especially at least 0.5 mW/lm, for all v’ values smaller than 0.45 (and of course within 10 SDCM from the Black Body Line, more especially within 7 SDCM from the Black Body Line).

In embodiments, v’<0.54, especially v’<0.53. The lower v’, the higher the relative impact of additional red radiation may be on the cytochrome C oxidase efficacy.

In specific embodiments (in an operation mode), especially wherein the color point of the lighting system light has a v’<0.53, the lighting system light may have a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.39) mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.875) mW/lm. Especially both conditions may apply. In such embodiments, the cytochrome C oxidase efficacy is even higher, and thus the beneficial impact on the ocular health may be stronger.

In yet more specific embodiments (in an operation mode), especially wherein the color point of the lighting system light (also) has a v’<0.54, even more especially v’<0.53, the lighting system light has a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least 1.05 mW/lm. Especially both conditions may apply. Hence, in embodiments the cytochrome C for the DNA synthesis is at least (6.2*v’-2.48) mW/lm, even more especially at least (6.2*v’-2.39) mW/lm, and/or the cytochrome C for the RNA synthesis is at least (7.5*v’-2.975) mW/lm, even more especially at least (6.2*v’-2.39) mW/lm. In further embodiments, additionally the cytochrome C for the DNA synthesis may also be at least 0.85 mW/lm and/or the cytochrome C for the RNA synthesis may also be at least 1.05 mW/lm. As indicated above, the lighting system may comprise in embodiments at least two types of different light sources. One type may essentially be used for generating white light, optionally depleted in red light, and another type may essentially be used for generating red light providing cytochrome C oxidase activation. For generating white light, a

luminescent material may be used to convert part of the light from the one types of light sources.

Hence, in embodiments the lighting system comprises at least two light sources and the one or more luminescent materials, wherein a first light source of the at least two light sources is configured to generate blue light source light, a second light source of the at least two light sources is configured to generate red light source light, and wherein a first luminescent material of the one or more luminescent materials is configured to convert at least part of the blue light source light into luminescent material light having one or more wavelengths in the green and yellow wavelength range. For instance, the first luminescent material may comprise a garnet material. The first luminescent material may especially generate light having a color point in the green or yellow. Note that the term“first luminescent material” may also refer to two or more different types of luminescent material configured to convert at least part of the blue light source light into luminescent material light having one or more wavelengths in the green and yellow wavelength range.

The terms“violet light” or“violet emission” especially relates to light having a wavelength in the range of about 380-440 nm. The terms“blue light” or“blue emission” especially relates to light having a wavelength in the range of about 440-495 nm (including some violet and cyan hues). The terms“green light” or“green emission” especially relate to light having a wavelength in the range of about 495-570 nm. The terms“yellow light” or “yellow emission” especially relate to light having a wavelength in the range of about 570- 590 nm. The terms“orange light” or“orange emission” especially relate to light having a wavelength in the range of about 590-620 nm.

Herein, the terms“red light” or“red emission” or“red radiation” especially relate to light having a wavelength in the range of about 620-1400 nm (including deep red and near infrared). The term“deep red” especially relates to light having a wavelength in the range of about 650-750 nm; the term“near infrared especially relates to radiation having a wavelength in the range of 750-1400 nm. Hence, the term“red light source light” may refer to light having a wavelength in the range of about 620-1400 nm. As the lighting system light in the operation mode (or one or more of the operation modes) is white light, the lighting system light will especially at least have one or more wavelengths in the range of 620-650 nm as the red component of the white light (in the art,“red” may refer to this wavelength of 620-650 nm).

The term“pink light” or“pink emission” refers to light having a blue and a red component.

The terms“visible”,“visible light” or“visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm, though larger wavelengths may also be visible.

The term“a wavelength” may also refer to a plurality of different wavelengths.

Terms like“first”,“second”, etc., may especially be used to distinguish between different types of light sources or different types of luminescent material, etc...

As can be derived from the activation spectra for cytochrome C oxidase chromophore for DNA and RNA synthesis, respectively, especially a few spectral positions are relevant. Hence, in embodiments a luminescent material and/or a solid state light source may be applied to generate radiation in the 550-900 nm wavelength range, especially in the 600-850 nm wavelength range, especially with one or more peak wavelengths within one or more of the following wavelength ranges: (i) 605-635 nm, (ii) 660-690 nm, (iii) 755-790 nm, and (iv) 800-835 nm.

Hence, light having a cytochrome C oxidase efficacy above zero may especially at least have wavelengths in the orange and red (including deep red and near infrared).

Instead of the term“activation spectra”, and similar terms, also the term “action spectra”, or similar terms, may be applied.

Hence, in specific embodiments the lighting system may comprise at least two light sources, wherein a second light source of the at least two light sources is configured to generate (red) light source light having a peak wavelength within one of the following wavelength ranges: (i) 605-635 nm, (ii) 660-690 nm, (iii) 755-790 nm, and (iv) 800-835 nm. For instance, in embodiments the lighting system may comprise a first light source which, optionally together with a luminescent material, is configured to generate white light (comprising one or more of the light source light of the first light source and the luminescent material light), and a second light source (optionally luminescent material based) configured to generate light source light having a peak wavelength within one of the following wavelength ranges: (i) 605-635 nm, (ii) 660-690 nm, (iii) 755-790 nm, and (iv) 800-835 nm. Hence, the lighting system may amongst others be based on a white light source and a mixing of one or more of orange and red (including deep red and near infrared) light. The different types of light sources are especially individually controllable (with the control system) such that the contributions of the light source light from each of the light sources to the lighting system light are controllable.

In yet further specific embodiments, the lighting system comprises a solid state light source (optionally in combination with a luminescent material) configured to generate first light (comprising light source light (from the solid state light source) and/or optional luminescent material light) having a wavelength in the spectral range of 620-650 nm, and another solid state light source (optionally in combination with (another)

luminescent material) configured to generate second light (comprising the light source light (from the solid state light source) and/or optional (other) luminescent material light) having a wavelength in one or more wavelength ranges selected from the group consisting of i) 660- 690 nm, (ii) 755-790 nm, and (iii) 800-835 nm, wherein the first light and the second light have different spectral power distributions.

Alternatively or additionally, in embodiments the lighting system may comprise the one or more luminescent materials, wherein a second luminescent material of the one or more luminescent materials is configured to convert at least part of the light source light into luminescent material light having a peak wavelength in a wavelength range of 600- 850 nm. Especially, in embodiments the second luminescent material may comprise a Mn⁴⁺ comprising luminescent material. In embodiments, the second luminescent material may be of the type M2AX6 doped with tetravalent manganese, wherein M comprises an alkaline cation, wherein A comprises a tetravalent cation, and wherein X comprises a monovalent anion, at least comprising fluorine (F). For instance, M2AX6 may comprise K1_.5Rbo_.5AX6. M relates to monovalent cations, such as selected from the group consisting of potassium (K), rubidium (Rb), lithium (Li), sodium (Na), cesium (Cs) and ammonium (NH₄ ⁺), and especially M comprises at least one or more of K and Rb. Preferably, at least 80%, even more preferably at least 90%, such as 95% of M consists of potassium and/or rubidium. The cation A may comprise one or more of silicon (Si) titanium (Ti), germanium (Ge), stannum (Sn) and zinc (Zn). Preferably, at least 80%, even more preferably at least 90%, such as at least 95% of A consists of silicon and/or titanium and/or germanium (not taking into account the partial replacement by Mn⁴⁺). Especially, M comprises potassium and A comprises titanium. X relates to a monovalent anion, but especially at least comprises fluorine. Other monovalent anions that may optionally be present may be selected from the group consisting of chlorine (Cl), bromine (Br), and iodine (I). Preferably, at least 80%, even more preferably at least 90%, such as 95% of X consists of fluorine. The term“tetravalent manganese” refers to Mn⁴⁺. This is a well-known luminescent ion. In the formula as indicated above, part of the tetravalent cation A (such as Si) is being replaced by manganese. Hence, M2AX6 doped with tetravalent manganese may also be indicated as M2Ai-_mMn_mX6. The mole percentage of manganese, i.e. the percentage it replaces the tetravalent cation A will in general be in the range of 0.1-15 %, especially 1-12 %, i.e. m is in the range of 0.001-0.15, especially in the range of 0.01-0.12. Further embodiments may be derived from WO2013/088313, which is herein incorporated by reference.

In specific embodiments, the color point is within 5 SDCM from the BBL, which may be even less off-white than within 7 SDCM.

Further, with the present system it may be possible to create lighting system light wherein the color rendering index of the lighting system light is at least 75, such as at least 80, like even at least 85. The higher the color rendering index, the better the color rendering of illuminated objects may be.

Further, with the present system it may be possible to create lighting system light wherein the lighting system light has a luminous efficacy of at least 40 lm/W, such as especially at least 105 lm/W. The higher photopic luminous efficacy, the more efficient the lighting system may be.

The power Watt in the unit of photopic luminous efficacy (such as in the phrase“luminous efficacy of at least 40 lm/W” and similar phrases) is especially the electrical power. This is the electrical power used to power the one or more solid state light sources. The term“electrical power” may also refer to the wall-plug power.

The term“spectral power” of a light spectrum may refer to the surface area under the spectrum graph of a light spectrum when expressed in W/nm versus nm. With respect to the cytochrome C oxidase efficacy, this efficacy is indicated in W/lm or mW/lm (i.e. milli Watt per lumen). The unit mW/lm especially refers to the spectral weighted Watts per lumen output. This is similar to other photoreceptor efficacies.

As indicated above, especially the system may further comprise a control system, for controlling optical properties of the lighting system light. Especially, in such embodiments the lighting system may comprise a plurality of (different) light sources, which may individually (or as subsets) be controlled.

Hence, in embodiments the lighting system may further comprise a controller or control system. In embodiments, the control system may control in dependence of one or more of a user input signal received from a user interface, a sensor signal received from a sensor and a timer. The term“timer” may refer to a clock and/or a predetermined time scheme. Instead of the term“timer” or“predetermined time scheme”, also the term“lighting schedule” may be applied. In embodiments, the control system may especially be configured to control the cytochrome C oxidase efficacy of the radiation in dependence of one or more of a user input signal, a lighting schedule and a sensor signal. The user input signal may be provided via a user interface. The lighting schedule may be predefined, may be defined by a user, may be imposed via an external signal, such as when the control system is temporarily or permanently connected with the internet, etc... Examples of time-based lighting schedules are further also indicated below. The sensor signal may be provided by a sensor, such as an optical sensor. The sensor may be a presence sensor. The sensor may be a proximity sensor. The sensor may be a daylight sensor. The sensor may be a temperature sensor. The sensor may be a camera. The sensor may be a sound sensor. The control system may derive from the sensor signal one or more of presence of people in a space, the number of people present in a space, an approximate age of one or more people in a space, a proximity of a person to the lighting system (i.e. a light emitting surface of the lighting system (more especially the lighting device)) etc. etc...

As indicated above, the lighting system light may have specific properties in an operation mode. The term“operation mode” may also refer to a plurality of different operation modes. In an operation mode, for instance, the cytochrome C oxidase efficacy may be controllable in relation to the intensity of the light or the correlated color temperature (or to both). For instance, when the intensity increases, blue light hazard may increase as, in absolute number of photons, more blue light is generated. Hence, it may be beneficial to also provide a higher cytochrome C oxidase efficacy component in the light output spectrum. When correlated color temperature increase, the relative blue content may be increased and hence, also in such embodiments, it may be beneficial to provide a higher cytochrome C oxidase efficacy component in the light output spectrum.

Hence, in embodiments the control system may be configured to control the cytochrome C oxidase efficacy and an optical property of the lighting system light, wherein the optical property is selected from the group of a correlated color temperature and a luminous flux of the lighting system light. Especially, the control system may be configured to control in an operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light such that over at least part of a dimming range of the optical property there is positive proportionality between the optical property and the cytochrome C oxidase efficacy. Herein, the term“dimming range” refers to the range over which the lighting system light and/or an optical property thereof may be dimmed up or dimmed down.

Up dimming of the correlated color temperature may thus especially indicate increasing the correlated color temperature; down dimming the correlated color temperature may thus especially indicate decreasing the correlated color temperature. Hence, in embodiments the phrase“over at least part of a dimming range of the optical property of the lighting system light” and similar phrases may refer to over at least part of a (dimming) range of the correlated color temperature of the lighting system light. Up dimming of the luminous flux may thus especially indicate increasing the luminous flux; down dimming the luminous flux may thus especially indicate decreasing the luminous flux. Hence, in (other)

embodiments the phrase“over at least part of a dimming range of the optical property of the lighting system light” and similar phrases may refer to over at least part of an intensity range of the luminous flux of the lighting system light.

The phrase“positive proportionality between the optical property and the cytochrome C oxidase efficacy” indicates that when increasing one of these, also the other increases, or when one of these decreases, also the other decreases.

Especially, in embodiments when the CCT is increased the cytochrome C oxidase efficacy of the lighting system light may (also) be increased; when the CCT is decreased the cytochrome C oxidase efficacy of the lighting system light may also be decreased. The proportionality may be linear or non-linear.

Especially, in embodiments when the luminous flux is increased the cytochrome C oxidase efficacy of the lighting system light may (also) be relatively increased (i.e. especially increases more than only due to the increase of the luminous flux); when the CCT is decreased the cytochrome C oxidase efficacy of the lighting system light may also be decreased (i.e. especially decreases more than only due to the decrease in CCT). Hence, cytochrome C oxidase efficacy may be controlled independently from, but in relation to, the total luminous flux. The proportionality may be linear or non-linear.

Alternatively or additionally, the control system may be configured to control in an operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light such that over at least part of a dimming range of the optical property there is negative proportionality between the optical property and the cytochrome C oxidase efficacy, wherein the optical property is the v\ When the blue content increases or when the CCT increases, in general the v’ value decreases. Hence, in such embodiments there may be a negative proportionality. The proportionality may be linear or non-linear. When changing the optical property, also the spectral power distribution may change.

Alternatively or additionally, it may be useful to keep the cytochrome C oxidase efficacy of the light substantially constant above a certain threshold value, even when varying other optical properties of the light as function of one or more received inputs.

Hence, in embodiments the control system may be configured to control in an operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light such that over at least part of a dimming range of the optical property the lighting system light has a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’- 2.975) mW/lm. In yet other embodiments, the control system may be configured to control in an operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light such that over at least part of a dimming range of the optical property the lighting system light has a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least 1.05 mW/lm.

In embodiments, the lighting system light may be subject to a time-based lighting schedule, such as a 24 hours scheme, or a 24/7 scheme, etc... For instance, the schedule may be used for office lighting, home lighting, hospitality lighting, etc. etc... Such lighting may take account of the natural variation in light over the day, or such schedule may take into account that the Equivalent Melanopic Lux (EML), as defined in the WELL Building Standard at certain periods may be chosen to increase or decrease alertness.

As known, next to the commonly known cones and rods, the human eye has melanopsin containing photoreceptors which are sensitive in a specific wavelength range (the melanopic wavelength range) and affect melatonin secretion. If the spectral power in the melanopic wavelength range is absent or low, melatonin hormone production is not inhibited to promote sleep. If the spectral power in the melanopic range is high enough, melatonin production will be suppressed and consequently may increase alertness. The effectiveness of suppressing melatonin production can be expressed in terms of the melanopsin effectiveness factor (MEF). This factor is calculated by multiplying the spectral power distribution of the light emitted by a lighting apparatus (8Rϋ(l)) with the melanopic sensitivity function (m(k)) divided by the product of SPD(å) and the photopic sensitivity function (V(å)), normalized by the areas of ih(l) and U(l), see equation below.

MEF = ( [SU(l)] / [åhi(l)]) · [å (SPD(å) · ih(l))] / [å (SPD(å) · U(l))]

This can be simplified to

MEF =1.22 · [å (SPD(å) · m(å))] / [å (SPD(å) · U(l))] or

Hence, the above indicated summations are over the visible range of 380-780 nm. The MEF formulas as well as the melanopic and photopic sensitivity functions are disclosed in WO2016146688A1. The URL

http://lucasgroup.lab.manchester.ac.uk/measuringmelanopicilluminance/ provides a toolbox with a listing of the melanopic and photopic sensitivity function.

Therefore, in embodiments the control system may also be configured to control in an operation mode the cytochrome C oxidase efficacy in dependence of or as a function of the EML or MEF of the light which may include a time-based lighting schedule.

The lighting system may in embodiments essentially consist of a lighting device. In other embodiments, the lighting system may comprise a lighting device and a control system, external of the lighting device. However, in other embodiments the control system may be comprised by the lighting device. Further, the lighting system may comprise one or more sensors. These sensors may be external from a lighting device or one or more sensors may be comprised by a lighting device. The lighting system may comprise a user interface, which may be external of a lighting device or which may be comprised by a lighting device. The term“lighting device” may also refer to a plurality of different lighting device. In an embodiment, the lighting system may comprise a plurality of different lighting devices.

In specific embodiments, the lighting system comprises a lighting device, wherein the lighting device comprises the one or more solid state light sources, especially at least two solid state light sources and the optional one or more luminescent materials. Such lighting device may be configured to generate lighting device light. Essentially all embodiments in relation to the lighting system en lighting system light may also relate to the lighting device and lighting device light. Hence, a lighting device may be an embodiment of a lighting system and lighting device light may be an embodiment of the lighting system light.

Hence, in yet a further aspect the invention also provides such lighting device, wherein the lighting device comprises the one or more solid state light sources, especially at least two solid state light sources and the optional one or more luminescent materials. The lighting device may be comprised by a luminaire. Hence, in yet a further aspect, the invention also provides a luminaire comprising the lighting device as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc...

In specific embodiments (of the lighting system, or the lighting device, or the luminaire (or the method)), a second light source of the at least two light sources is configured to generate red light source light having a peak wavelength within one of the following wavelength ranges: (i) 660-690 nm, and (ii) 755-790 nm.

In yet a further aspect, the invention also provides a method of controlling in an operation mode lighting system light of a lighting system, wherein a spectral power distribution of the lighting system light is selectable and/or controllable, wherein the method comprises selecting and/or controlling an amount of red, deep red or near infrared light in spectral power distribution of the lighting system light in dependence of one or more of a user input signal, a lighting schedule, and a sensor signal, and maintaining during the operation mode the following conditions:

(a) the lighting system light is white light characterized by a color point within 10 SDCM, especially within 7 SDCM, from the Black Body Line; and

(b) the lighting system light has a cytochrome C oxidase efficacy complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm, wherein the cytochrome C oxidase efficacy is defined as: wherein:

b_,lO'O ⁼ is the spectral power distribution of the lighting system light;

s_cyt ( -) = is the spectral sensitivity of cytochrome C oxidase activation for either DNA synthesis or RNA synthesis;

V(X) = is the photopic luminosity function; and

v’ is a color coordinate of the lighting system light in the CIE 1976 UCS (uniform

chromaticity scale) diagram.

In an embodiment of the method, the lighting system light has a luminous efficacy of at least 40 lm/W.

In yet a further aspect, the invention also provides a computer program product, which, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system. In yet a further aspect, the invention also provides a computer program product, which, when running on a computer which is functionally coupled to or comprised by a device, an apparatus, or a system, such as e.g. described herein, executes the herein described method.

The lighting system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive

applications, (outdoor) road lighting systems, urban lighting systems, etc...

The lighting system may be configured such that during operation normal use will not lead to flux of more than 1 cytochrome C oxidase weighted mW/cm² on the eye.

Hence, amongst others, the invention provides a lighting system comprising (i) one or more solid state light sources configured to generate light source light and optionally (ii) one or more luminescent materials configured to convert at least part of the light source light into luminescent material light, wherein the lighting system is configured to generate in an operation mode lighting system light comprising one or more of the light source light and the optional luminescent material light, wherein the one or more solid state light sources and the optional one or more luminescent materials are selected to provide the lighting system light in the operation mode with the condition that (a) the lighting system light is white light, and (b) the lighting system light has a minimum efficacy in activating cytochrome C oxidase in human tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Fig. 1 displays the Cytochrome C oxidase action spectral curves for DNA synthesis and RNA synthesis. The horizontal axis represents the wavelength in nm, the vertical axis represents the relative spectral sensitivity;

Fig. 2a displays the cytochrome C oxidase (DNA synthesis, see Fig. 1 action spectrum) efficacy E (expressed in Cytochrome-C-DNA-synthesis weighted mW/lm) for a multitude of common white light sources. The rising linear line represents a Cytochrome C DNA efficacy described by 6.2 * v’ - 2.48 mW/lumen. The horizontal line represents a Cytochrome C DNA efficacy of 0.85 mW/lm, this being the highest Cytochrome C oxidase efficacy of all light sources plotted in the figure;

Fig. 2b displays the Cytochrome-C oxidase (RNA synthesis, see Fig. 1 action spectrum) efficacy E (expressed in Cytochrome-C-RNA-synthesis weighted mW/lm) for a multitude of common white light sources. The rising linear line represents a Cytochrome C RNA efficacy described by 7.5 * v’ - 2.975 mW/lumen. The horizontal line represents a Cytochrome C RNA efficacy of 1.05 mW/lm, this being the highest value in the figure;

Figs. 3a-3b schematically depict embodiments of the lighting system (or of the lighting device); and

Fig. 4 displays some examples.

The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It was found that with deep red and NIR light the mitochondrial activity can be improved in ocular tissues/(animal) models, indicating that visual -function and eye-health related problems like AMD and glaucoma, can be improved. The mitochondrial activation can be realized by the chromophore Cytochrome C oxidase in the mitochondria that absorb deep red/NIR light and stimulates amongst others the production of ATP, the primary source of energy for cells. Cytochrome-C oxidase stimulation by (deep) red light can be calculated based on the spectral sensitivities as defined by T. Karu, who measured DNA and RNA transcription effects mediated through Red and NIR light via the Cytochrome C oxidase pathway (see also http://photobiologv.info/Karu.html; Action Spectra, Their Importance for Low Level Light Therapy).

Fig. 1 gives the curves of the cytochrome C sensitivity functions for the DNA and RNA synthesis routes. Note there is substantial spectral overlap, but in some wavelength ranges the peak maxima (substantially) differ. For this reason, both the DNA and RNA cytochrome C oxidase efficacy are herein defined.

The cytochrome-C action spectra curves of Fig. 1, which are normalized to 1, can be multiplied with the spectral radiant flux (in mW) to calculate the Cytochrome C absorption/activation per visible lumen for that particular type of radiation. This quantity expresses the Cytochrome C oxidase efficacy (in weighted mW/Lm) of a light source and is calculated for many commercially available light sources and plotted as the“Cytochrome C DNA effectiveness” and“Cytochrome C RNA effectiveness”, see also Figs 2a and 2b, respectively.

The content of deep red and NIR light in the current electrical light sources is minimal. The presently proposed deep red/NIR enhanced spectra are different from the current available artificial light sources known and has the potential to delay (or even prevent) the onset of retinal diseases. The stimulation can be quantified with a Cytochrome C effectiveness factor. A red enhanced light spectrum may also be expected to have a positive effect on visual-comfort and/or eye-fatigue during prolonged light exposures. The light sources displayed as points in Figs. 2a and 2b are artificial/electrical light sources within 10 SDCM from the BBL, hence each point in the figures represents one particular (spectral) kind of white light source.

Figs. 2a and 2b also show the conditions for the DNA or RNA cytochrome C oxidase efficacy; see further also below. Specific conditions (not displayed in these Figures) may be: v’<0.53, and a cytochrome C oxidase efficacy of radiation complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.39) mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.875) mW/lm.

There are several ways to create spectra that fulfil the Cytochrome C oxidase efficacy criteria limits as defined above, such as for instance: • Phosphor converted LED with a deeper Red and or narrow Red phosphor at the correct position to enhance the cytochrome-C efficacy

• A combination of LED’s, of blue, green (lime) and red (or mixture of

Red/deep red/NIR) LED’s.

• A combination of white LED’ s and a Deep red and/or NIR LED’ s (standard white LEDs in combination with NIR LEDs, as these do not influence the color point)

Figs 3a-3b schematically depict embodiments of the lighting system 1000 (or lighting device 100).

Fig. 3a schematically depicts an embodiment of the lighting system 1000, wherein the lighting system 1000 comprises (i) one or more solid state light sources 10 configured to generate light source light 11 and optionally (ii) one or more luminescent materials 20 configured to convert at least part of the light source light 11 into luminescent material light 21.

Fig. 3a schematically depicts a number of variants in a single drawing.

Further, more features than displayed can be present.

Here, by way of example an embodiment is depicted wherein the lighting system 1000 comprises a lighting device 100, wherein the lighting device 100 comprises the one or more solid state light sources 10, and the optional one or more luminescent materials 20. A housing may be provided, with one or more, especially two or more different types of solid state light sources 10. Here, luminescent material 20 is depicted in close proximity of the solid state light sources. However, remote configurations of the luminescent material(s) may also be possible. The lighting device 100 may comprise a diffusor. The lighting device may comprise a window, through which lighting system light escapes. The window is indicated with reference 105. The window may be a diffusor. The window may be a polymeric or glass window, etc. The light source(s) 10 and the luminescent material(s) may be configured upstream of the window 105. The terms“upstream” and“downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is“upstream”, and a third position within the beam of light further away from the light generating means is“downstream”. The lighting device 100 is configured to generate lighting device light 101 (which, in the schematically depicted embodiment is essentially the same as the lighting system light 1001). Especially, the lighting system 1000 is configured to generate in an operation mode lighting system light 1001 comprising one or more of the light source light 11 and the optional luminescent material light 21. Further, especially the one or more solid state light sources 10 and the optional one or more luminescent materials 20 are selected to provide the lighting system light 1001 in the operation mode with one or more of the following conditions:

(a) the lighting system light 1001 is white light characterized by a color point within 10 SDCM, especially within 7 SDCM from the Black Body Line;

(b) the lighting system light 1001 has a luminous efficacy of at least 40 lm/W;

(c) the lighting system light 1001 has a cytochrome C oxidase efficacy CC eff of radiation complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’- 2.975) mW/lm or is at least 1.05 mW/lm, wherein the cytochrome C oxidase efficacy is defined as:

Cytochrome C oxidase Efficacy of radiation (W / Lm ) =

tral power distribution of the lighting system light 1001;

sc_yt(A) = is the spectral sensitivity of cytochrome C oxidase activation for either DNA synthesis or RNA synthesis;

V(X) = is the photopic luminosity function; and

v’ is a color coordinate of the lighting system light (1001) in the CIE 1976 UCS (uniform chromaticity scale) diagram.

Fig. 3a schematically depicts an embodiment wherein the lighting system 1000 comprises at least two light sources 10 and the one or more luminescent materials 20. A first light source 1110 of the at least two light sources 10 may be configured to generate blue light source light 11. A second light source 1210 of the at least two light sources 10 may be configured to generate red light source light 11. A first luminescent material 1120 of the one or more luminescent materials 20 may be configured to convert at least part of the blue light source light 11 into luminescent material light 21 having one or more wavelengths in the green and yellow wavelength range (such as a cerium comprising garnet material). Fig. 3a may also schematically depict an embodiment wherein the lighting system 1000 comprises at least two light sources 10, wherein a second light source 1210 of the at least two light sources 10 may be configured to generate red light source light 11 having a peak wavelength within one of the following wavelength ranges: (i) 605-635 nm,

(ii) 660-690 nm, (iii) 755-790 nm, and (iv) 800-835 nm. This may be a red LED (without phosphor conversion).

In specific embodiments, the second light source 1210 of the at least two light sources 10 is configured to generate red light source light 11 having a peak wavelength within one of the following wavelength ranges: (i) 660-690 nm, and (ii) 755-790 nm (see e.g. also below examples 1 and 2).

Fig. 3a may also schematically depict an embodiment wherein the lighting system (1000) comprises the one or more luminescent materials (20), wherein a second luminescent material (1220) of the one or more luminescent materials (20) is configured to convert at least part of the light source light (11) into luminescent material light (21) having a peak wavelength in a wavelength range of 600-850 nm. This may be based on a phosphor conversion LED. Note that in Fig. 3a two different phosphor conversion LEDs are schematically depicted. In embodiments, the two different LEDs may generate different colors. In other embodiments, both LEDs may comprise two (or more) different luminescent materials). In embodiments, the second luminescent material (1220) comprises a Mn⁴⁺ comprising luminescent material (see e.g. also below Examples 2 and 3).

As schematically depicted, in embodiments the lighting system 1000 may further comprising a control system 30, wherein the control system is configured to control the cytochrome C oxidase efficacy in dependence of one or more of a user input signal, a lighting schedule, and a sensor signal. Further, the lighting system may comprise a user interface 40. Yet further, the lighting system may comprise one or more sensors 50.

As indicated above, the control system 30 may be configured to control the cytochrome C oxidase efficacy and an optical property of the lighting system light 1001, wherein the optical property is selected from the group of a correlated color temperature and a luminous flux of the lighting system light 1001. Yet further, the control system 30 may be configured to control in an operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light 1001 such that over at least part of a dimming range of the optical property there is positive proportionality between the optical property and the cytochrome C oxidase efficacy. In embodiments, the control system 30 may be configured to control in an operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light 1001 in dependence of a time-based lighting schedule.

EXAMPLES

A combination of a white LED with a deep red emitter was provided, see further details in the table below. A spectral solution can be made by for instance adding a NIR LED, while maintaining the color of the standard white LED. The solution shown in Fig. 4 (Ex. 1) has a cytochrome-C oxidase DNA efficacy of 0.98 at a v’ of 0.527. The luminous efficacy of such a source will be well over 40 Lm/W : combining 1W of white light with an efficiency of 150 Lm/W with 0.25 W of NIR light will yield a light source with an overall efficiency of 100 Lm/W.

Further examples were also simulated, see Examples 2-4 in the table. The spectral distributions of these examples are shown in Fig. 4.

An incandescent source for instance has a Cytochrome C DNA efficiency of >1.4 at a v’ of 0.524, significantly above the horizontal line given in Fig. 2a, but an efficacy above much lower than 40 lm/W. These sources, however, suffer from a low luminous efficacy. All LED sources, C DM4 ike sources, etc. are below the lines in Figs 2a and 2b. Daylight 6500K has a Cytochrome C DNA Efficacy value of >0.75 at a v’ of 0.468, which is also higher than traditional light sources at a similar color point.

In embodiments, the control system may be configured to maintain a threshold of specific value (range) for the CRI and also control the cytochrome C oxidase efficacy in dependence of the v’ value.

In embodiments, the control system may control the cytochrome C oxidase efficacy in dependence of the lumen output/light intensity of the system/element, and e.g. (automatically) increase when the lumen output/light intensity of the lighting system/element increases (as to reduce the potential damaging impact of its high intensity light, for instance in a reading light, or in a light therapy device) (and decrease vice versa).

In embodiments, the control system may control the cytochrome C oxidase efficacy in dependence of a value related to the Blue Light Hazard (or the blue light Hazard efficacy / lumen) light generated by the lighting system, and e.g. (automatically) increases the cytochrome C oxidase efficacy when the BLH (or the BLH efficacy /lumen) of the system/element increases (as to reduce the potential damaging impact of blue-rich light of the system/element) (and decrease vice versa).

In embodiments, the control system may control the cytochrome C oxidase efficacy in dependence of a melanopic (ir)radiance (or the melanopic efficacy / lumen, or the MEF) of the light generated by the lighting system/, and e.g. (automatically) increases when the melanopic (ir)radiance (or the melanopic efficacy / lumen, or the MEF) of the

system/element increases (as to reduce the potential damaging impact of blue rich, biologically more active (and melanopsin stimulating) high MEF light, for instance in a reading light, or in a light therapy device) (and decrease vice versa).

In embodiments, the control system may e.g. first increase the cytochrome C oxidase efficacy before it changes the intensity/melanopic (ir)radiance, as to pre-protect the retina for the potentially more harmful (i.e., brighter, more blue) subsequent light exposure.

In embodiments, the control system may be configured to control the cytochrome C oxidase efficacy in dependence on the time of day, or the internal (circadian) time of the user (such as e.g. for shift work applications or for people who are travelling).

This can be used to reduce the damaging action of nocturnal light.

In embodiments, the lighting system may be generated to provide lighting system light with a multi-hour dynamic rhythm (or light dark cycle) in which intensity and spectrum is (automatically and/or cyclically) varied over time and where during part of the light cycle the light emission is characterized by a cytochrome C oxidase efficacy complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm.

In embodiments, the lighting system may be configured to allow a user adjust the spectral composition of the lighting system light, while control system is configured to automatically secures that the Cytochrome C oxidase efficacy complies with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm. If needed, the system will automatically adjust the color point of the emitted light so that the threshold criterium continues to be met. Cooler colors generically may have lower deep red/NIR content but have higher values of the high energetic wavelength (blue, violet) in the spectrum.

In embodiments, the control system may be configured to control the

Cytochrome C oxidase efficacy (and/or the BLH efficacy) in dependence on the age of the user or on the ocular health of the user. As soon a single user with a high age or certain ocular pathology enters the light exposure area with multiple users, the system may e.g. increase the Cytochrome C oxidase efficacy /lumen (and/or decreases the BLH

efficacy /lumen) to match the needs of that user.

In embodiments, the control system may be configured to control the cytochrome C oxidase efficacy in dependence of a spatial light distribution and/or brightness contrasts in the room. When the spatial distribution results in more glare and/or eye discomfort, the Cytochrome C oxidase efficacy may be increased (assuming this has a protective effect against eye fatigue and visual discomfort) (and decrease vice versa).

The term“plurality” refers to two or more.

The terms“substantially” or“essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms“substantially” or“essentially” may also include embodiments with“entirely”,“completely”,“all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term“essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

The term“comprise” includes also embodiments wherein the term “comprises” means“consists of’. The term“and/or” especially relates to one or more of the items mentioned before and after“and/or”. For instance, a phrase“item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an

embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words“comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; in the sense of“including, but not limited to”.

The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A lighting system (1000) comprising (i) one or more solid state light sources

(10) configured to generate light source light (11) and optionally (ii) one or more luminescent materials (20) configured to convert at least part of the light source light (11) into

luminescent material light (21), wherein the lighting system (1000) is configured to generate in an operating mode lighting system light (1001) comprising one or more of the light source light (11) and the optional luminescent material light (21), wherein the one or more solid state light sources (10) and the optional one or more luminescent materials (20) are selected and/or controlled to provide in the operating mode the lighting system light (1001) with a selectable and/or controllable amount of red, deep red or near infrared lightwith the following conditions:

(a) the lighting system light (1001) is white light characterized by a color point a color point within 10 SDCM from the Black Body Line; and

(b) the lighting system light (1001) has a cytochrome C oxidase efficacy complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm, wherein the cytochrome C oxidase efficacy is defined as:

wherein:

F_b,l(A) ⁼ is the spectral power distribution of the lighting system light (1001);

V(X) = is the photopic luminosity function; and

v’ is a color coordinate of the lighting system light (1001) in the CIE 1976 UCS (uniform chromaticity scale) diagram;

the lighting system comprising a control system configured to control in the operation mode of the lighting system the cytochrome C oxidase efficacy in dependence of one or more of a user input signal, a lighting schedule, and a sensor signal.

2. The lighting system (1000) according to claim 1, wherein the lighting system (1000) comprises at least two light sources (10) and the one or more luminescent materials (20), wherein a first light source (1110) of the at least two light sources (10) is configured to generate blue light source light (11), a second light source (1210) of the at least two light sources (10) is configured to generate red light source light (11), and wherein a first luminescent material (1120) of the one or more luminescent materials (20) is configured to convert at least part of the blue light source light (11) into luminescent material light (21) having one or more wavelengths in the green and yellow wavelength range.

3. The lighting system (1000) according to any one of the preceding claims, wherein the lighting system (1000) comprises at least two light sources (10), wherein a second light source (1210) of the at least two light sources (10) is configured to generate red light source light (11) having a peak wavelength within one of the following wavelength ranges: (i) 605-635 nm, (ii) 660-690 nm, (iii) 755-790 nm, and (iv) 800-835 nm.

4. The lighting system (1000) according to any one of the preceding claims, wherein the lighting system (1000) comprises the one or more luminescent materials (20), wherein a second luminescent material (1220) of the one or more luminescent materials (20) is configured to convert at least part of the light source light (11) into luminescent material light (21) having a peak wavelength in a wavelength range of 600-850 nm.

5. The lighting system (1000) according to claim 4, wherein the second luminescent material (1220) comprises a Mn⁴⁺ comprising luminescent material.

6. The lighting system (1000) according to any one of the preceding claims, wherein v’<0.53, and wherein the lighting system light (1001) has a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.39) mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.875) mW/lm.

7. The lighting system (1000) according to any one of the preceding claims, wherein v’<0.53, and wherein the lighting system light (1001) has a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least 1.05 mW/lm.

8. The lighting system (1000) according to any one of the preceding claims, wherein the color point of the lighting system light (1001) is within 7 SDCM from the Black Body Line, wherein the color rendering index of the lighting system light (1001) is at least 75, and wherein the lighting system light (1001) has an efficacy of at least 105 lm/W.

9. The lighting system (1000) according to any one of the preceding claims, wherein the control system (30) is configured to control in the operation mode the cytochrome C oxidase efficacy and an optical property of the lighting system light (1001), wherein the optical property is selected from the group of a correlated color temperature and a luminous flux of the lighting system light (1001).

10. The lighting system (1000) according to claim 9, wherein the control system (30) is configured to control in the operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light (1001) such that over at least part of a dimming range of the optical property there is a positive proportionality between the optical property and the cytochrome C oxidase efficacy.

11. The lighting system (1000) according to any one of the preceding claims 9-10, wherein the control system (30) is configured to control in the operation mode the cytochrome C oxidase efficacy and the correlated color temperature of the lighting system light (1001) such that over at least part of a range of the correlated color temperature the lighting system light (1001) has a cytochrome C oxidase efficacy complying with one or more of the following conditions: (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm.

12. The lighting system (1000) according to any one of the preceding claims 9-11, wherein the control system (30) is configured to control in the operation mode the cytochrome C oxidase efficacy and the optical property of the lighting system light (1001) in dependence of a time-based lighting schedule.

13. The lighting system (1000) according to any one of the preceding claims, comprising a lighting device (100), wherein the lighting device (100) comprises the one or more solid state light sources (10) and the optional one or more luminescent materials (20).

14. A method of controlling in an operation mode lighting system light (1001) of a lighting system (1000), wherein a spectral distribution of the lighting system light (1001) is selectable and/or controllable, wherein the method comprises selecting and/or controlling an amount of red, deep red or near infrared light in the spectral distribution of the lighting system light (1001) in dependence of one or more of a user input signal, a lighting schedule, and a sensor signal, and maintaining during the operation mode the following conditions:

(a) the lighting system light (1001) is white light characterized by a color point within 10 SDCM from the Black Body Line; and

(b) the lighting system light (1001) has a cytochrome C oxidase efficacy CC eff of radiation complying with one or more of the following conditions (i) the cytochrome C oxidase efficacy for DNA synthesis is at least (6.2*v’-2.48) mW/lm or is at least 0.85 mW/lm, and (ii) the cytochrome C oxidase efficacy for RNA synthesis is at least (7.5*v’-2.975) mW/lm or is at least 1.05 mW/lm, wherein the cytochrome C oxidase efficacy is defined as:

wherein:

V(X) = is the photopic luminosity function; and v’ is a color coordinate of the lighting system light (1001) in the CIE 1976 UCS (uniform chromaticity scale) diagram.

15. The method of claim 14, wherein the lighting system light (1001) has a luminous efficacy of at least 40 lm/W.