Black vision light system using cyan-pumped white LEDs

Abstract

A light generating system generating system light, comprising a first light generating device and a second light generating device, wherein: the first light generating device is configured to generate first device light, wherein the first light generating device comprises (i) a first light source configured to generate first source light having a first dominant wavelength selected from the range of 470-500 nm, and (ii) a first luminescent material configured to convert a portion of the first source light into first luminescent material light; wherein the first device light comprises the first source light and the first luminescent material light; and wherein the first device light has a first color point; the second light generating device is configured to generate second device light, wherein the second light generating device comprises (i) a second light source configured to generate second source light having a second dominant wavelength, and (ii) a second luminescent material configured to convert at least a portion of the second source light into second luminescent material light; wherein the second device light comprises the second luminescent material light; and wherein the second device light is white light having a second color point and a second correlated color temperature Tc2.

Description

TECHNICAL FIELD

[0001] The present invention relates to a light generating system and a luminaire or lighting device comprising such a light generating system. BACKGROUND

[0002] Solid state light emitting devices comprising an adjustable melatonin suppression effect are known in the art. For example, US 9039746 describes a solid state light emitting device comprising a plurality of LED components providing an adjustable melatonin suppression effect. The plurality of LED components can be operated simultaneously according to different operating modes according to which their combined output provides the same or similar chromaticity but provides a melatonin suppression effect that differs between the different operating modes by at least a predetermined threshold amount. Switching between the operating modes can be triggered by a user input element, a timer / clock or a sensor (e.g. a photo sensor). It is also possible to adjust the chromaticity of the combined output of the plurality of LED components while providing an adjustable melatonin suppression effect at each selected combined output chromaticity. SUMMARY

[0003] Melatonin, a hormone that promotes sleep at night, is key to our sleep / wake cycle. Melatonin is a sleep-supporting hormone that is produced only around (and during) our usual bedtime. Exposure to light in the evening and at night suppresses the natural production of melatonin. When the spectrum of light shifts towards lower CCT and intensity levels (as during dawn and dusk), this reduces the melatonin suppression and makes the light less disruptive to sleep. During the day, natural daylight with a high correlated color temperature (CCT, also denoted as "color temperature" herein) and intensity provides people with energy, making them wake up and alert. Current high performance LED-based lighting devices with tunable CCT are able to mimic the different stages of daylight (i.e. changes in spectral power distribution and changes in CCT) to a certain extent.

[0004] In addition to the generally known cones and rods, the human eye has melanopsin containing photoreceptors that influence the circadian entrainment and melatonin secretion that are sensitive in a specific wavelength range. In Figure 6 The relative spectral sensitivity of the classical receptors (rods and cones) and the melanopsin receptors is provided in Figure 1 of WO 2016 / 028 1 1 1 Al (see also R.J. Lucas et al., Measuring and using light in the melanopsin age, Trends in Neurosciences, Vol. 37, No. 1, January 2014, pp. 1 -9; http: / / www.sciencedirect.com / science / article / pii / S0166223613001975, Report "CIETN 003:2015: Report on the First International Workshop on Circadian and Neurophysiological Photometry, 2013" http: / / cie.co.at / index.php?i_ca_id= 978 (with link to excel toolbox http: / / files.cie.co.at / 784_TN003_Toolbox.xls ). If the spectral power in the scotopic wavelength range is absent or low, the suppression of melatonin production by exposure will be less, enabling faster sleep onset and more consolidated sleep. If the spectral power in the scotopic range is increased, the exposure will result in stronger melatonin suppression. In general, when the power in the scotopic range (and the ability to suppress melatonin during the night) is increased, it can be said that the exposure has a higher biological activity and is more alerting. The effectiveness of a given spectrum in suppressing melatonin production can be expressed in a melanopic effectiveness factor (MEF). This factor is calculated by multiplying the spectral power distribution (SPD(λ)) of the light emitted by the lighting system by the scotopic sensitivity function (m(λ)), divided by the product of the SPD(λ) and the photopic luminosity function (V(λ)), normalized by the area under m(λ) and V(λ), see equation 1 (see also Figure 1 ).

[0005]

[0006] This can be simplified to

[0007]

[0008]

[0009] Hence, the above sum is in the visible range of 380-780 nm. By definition, an equi-energy light source MEF EE has a MEF equal to 1. In particular, an equi-energy light source has an SPD(λ) = constant (e.g. 1) for all (visible) wavelengths.

[0010] The maximum sensitivity of this sensor in the human eye (intrinsic photoreceptive retinal ganglion cells or iPRGCs) is around 490 nm. Stimulation of iPRGCs during the day (or lack of stimulation at night) is important for controlling the circadian rhythm (entrainment of the 24-hour cycle).

[0011] The melanopic efficiency of a spectrum can be calculated using the MDEF (Melanopic D65 Efficiency Factor) (sometimes also denoted as MDER, i.e. Melanopic Daylight Efficacy Ratio). In this case, instead of an equal-energy light source, a D65 light source (i.e. CIE standard illuminant D65) is used, which is a commonly used standard light source defined by the International Commission on Illumination (CIE). The MDEF can be defined as the lux illumination of a D65 source that is required to produce the same iPRGCs stimulus per lux of the test source (or test system). The MDEF value for a D65 source is approximately 0.906*MEF value. Instead of the MDEF value, also the MELR value can be applied. The term MELR refers to the melanopic efficacy of the emitted light (mW / Lm).

[0012] Instead of the MDEF value, also the MELR value (Melanopic Efficacy of the emitted light) can be used. With respect to the calculation of the MDEF value and the MELR value, the following can be mentioned. For the test spectrum to be evaluated, it can be calculated how many mW are in the spectral region of the test spectrum (by weighting the spectrum with m( ). It can also be calculated how many Lm are produced. The ratio of the power in mW to the lumens in Lm is called the MELR value. For the D65 reference spectrum, this calculation can also be made. The MELR of D65 = 1.326 mW / Lm. The ratio of the MELR value of the test spectrum to be evaluated to the MELR value of the reference spectrum (D65) is called the MDEF (or MDEF value). The MDEF, is a value without units.

[0013] Thus, the MELR can be expressed in mW / Lm, where the mW is calculated from The lumens in Lm are calculated in the normal way.

[0014] As mentioned above, especially the MDEF is applied, which is further denoted herein as MDER. The MDER is defined as:

[0015]

[0016] where SPD( ) is the spectral power distribution of the light emitted by the light emitting device, m( ) is the melanopic sensitivity function, and V( ) is the photopic luminance function.

[0017] As mentioned above, the biological effect of the illumination is the product of the illuminance (lux at the eye) * MDER * (exposure time). Secondly, the exposure time (morning / night) also determines the influence on the person. Under normal indoor lighting conditions, the iPRGCs stimulus is too low during the day (e.g. 500 lux, 4000 K, MDER ~ 0.6 in an office).

[0018] It seems desirable to enrich the illumination with blue light. However, using a direct blue emitter in combination with a white LED to boost the spectrum of the light can have a large disadvantage. The strongly deviating color point (the direct blue emitter is not a white LED, but a light blue / green) prohibits the use in an illumination system without sufficient (color) mixing. Therefore, the approach using a direct blue emitter cannot be used in e.g. panels (side or direct illumination) or in illumination systems using lenses. In case the light emitted by the blue enhanced LED is white, these problems can be reduced or even absent. However, a tunable system using a white LED in combination with a blue pumped LED can only achieve a very limited tuning range. Furthermore, a blue pumped white LED with a deep red phosphor having an emission peak intensity between 640 and 680 nm seems to be very inefficient.

[0019] It is therefore an aspect of the present application to provide an alternative illumination system which preferably further at least partially obviates one or more of above-described drawbacks. It can be an aim of the present application to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide the public with a useful alternative.

[0020] Thus, in a first aspect, the present application provides a light generating system configured to generate system light. The light generating system comprises a first light generating device and a second light generating device. The first light generating device is configured to generate first device light. In particular, the first light generating device comprises (i) a first light source configured to generate first light source light having a first dominant wavelength Adi. In a particular embodiment, the first dominant wavelength Adi is selected from the range of 470-500 nm. Further, in particular, the first light generating device comprises (ii) a first luminescent material configured to convert a portion of the first light source light into first luminescent material light. In particular, the first device light comprises the first light source light and the first luminescent material light. In a particular embodiment, the first device light has a first color point. Further, the second light generating device is configured to generate second device light. In particular, the second light generating device comprises (i) a second light source configured to generate second light source light having a second dominant wavelength Ad2. Further, in particular, the second light generating device comprises (ii) a second luminescent material configured to convert at least a portion of the second light source light into second luminescent material light. In particular, the second device light comprises the second luminescent material light and optionally the second light source light. In a particular embodiment, the second device light has a second color point. In particular, the second device light is white light having a second correlated color temperature Tc2. In particular in embodiments Adi - Ad2 > 10 nm. Further, in particular, the spectral power distributions of the first light source light and the second light source light are different. In a particular embodiment, the first color point and the second color point have a maximum difference of 0.03 for u’ and / or a maximum difference of 0.03 for v’. In particular, the color points u’ and v’ are based on the 10° color matching functions according to CIE S 0140-1 / E:2006 (see Table 2 of CIE S 014-1 / E:2006) (also denoted herein as “10° CMF” and similar phrases).Thus, in particular, the present application provides in an embodiment a light generating system configured to generate system light, wherein the light generating system comprises a first light generating device and a second light generating device, wherein: (a) the first light generating device is configured to generate first device light, wherein the first light generating device comprises (i) a first light source configured to generate first light source light having a first dominant wavelength λdi selected from the range of 470-500 nm, and (ii) a first luminescent material configured to convert part of the first light source light into first luminescent material light; wherein the first device light comprises the first light source light and the first luminescent material light; and wherein the first device light has a first color point; (b) the second light generating device is configured to generate second device light, wherein the second light generating device comprises (i) a second light source configured to generate second light source light having a second dominant wavelength λd2, and (ii) a second luminescent material configured to convert at least part of the second light source light into second luminescent material light; wherein the second device light comprises the second luminescent material light and optionally the second light source light; and wherein the second device light has a second color point (and wherein in particular the second device light is white light having a second correlated color temperature Tc2); (c) λdi - λd2≥ 10 nm; (d) the spectral power distributions of the first light source light and the second light source light are different; and (e) the first color point and the second color point have a maximum difference in u’ of 0.03 and / or a maximum difference in v’ of 0.03 (using the 10° color matching functions according to CIE S 014-1 / E:2006 (see Table 2)).

[0021] Herein, color points are in particular defined using the 10 degrees color matching functions according to CIE S 014-1 / E:2006 (see Table 2). Color temperatures are based on the CIE 1960 diagram (u, v values, i.e. using the CIE 1931 2 degrees color matching functions).

[0022] It appears that combining a cyan-pumped LED and a blue-pumped LED having the same color of the second channel allows to generate a tunable system having a large tuning range. In this way, the lighting system can have a fixed or variable MDER, and also a possibly variable correlated color temperature (CCT). Further, combining a cyan-pumped LED and a blue-pumped LED having the same color can also be used in this way to provide a lighting system having a so improved MDER. In this way, the lighting system can be equipped with a fixed or variable MDER, having a substantially fixed correlated color temperature (CCT).

[0023] As mentioned above, the present application provides a light generating system configured to generate system light, wherein the light generating system comprises a first light generating device and a second light generating device.

[0024] The term "first light generating device" can also refer to a plurality of substantially identical light generating devices (such as from the same bin). The term "second light generating device" can also refer to a plurality of substantially identical light generating devices (such as from the same bin). The terms "first light generating device" and "second light generating device" especially refer to devices that differ, in particular in one or more spectral properties. Herein, the spectral distribution is different and for example the color rendering index (CRI) can differ substantially, such as by at least 10 points. Hence, the spectral power distribution of the first light source light and the second light source light is different. However, the color point can be substantially the same. Hence, in embodiments, the first color point and the second color point can differ maximally by 0.03 for u' and / or by 0.03 for v' (such as maximally by 0.02 for u' and / or by 0.02 for v'). Even more particularly, in embodiments, the first color point and the second color point can differ maximally by 0.01 for u' and / or by 0.01 for v'. For the u' and v' values, especially the 10° color matching functions according to CIE S 014-1 / E:2006 (see Table 2) apply (i.e. the 10° color matching functions). Further, the phrase "the light generating system comprises a first light generating device and a second light generating device" does not exclude the presence of further light generating devices. As will be shown below, in a number of embodiments, the light generating system can comprise a further (third) light generating device. Herein, the term "illumination system" or "system" can also be applied instead of the term "light generating system". Further, herein, the term "illumination device" or "device" can also be applied instead of the term "light generating device".

[0025] Herein, the light generating device especially comprises a solid state light source (see further below as well).

[0026] As indicated above, the first light generating device and the second light generating device are substantially different, such as providing device light with different spectral power distributions. However, the color point can be substantially the same. Below, some embodiments are described with respect to the first light generating device and the second light generating device.

[0027] The first light generating device is configured to generate first device light.

[0028] In particular, the first light generating device comprises a first light source configured to generate first light source light having a first dominant wavelength λdi. The first light source especially comprises a solid state light source, such as an LED. The first dominant wavelength λdi is especially selected from the range of 470-500 nm. Hence, the first light source is especially a cyan light source, e.g. a cyan LED. More particularly, the first dominant wavelength λdi can be selected from the range of 470-490 nm. Best results can be obtained with a first dominant wavelength λdi selected from the range of 475-485 nm. Even more particularly, the first dominant wavelength λdi can be selected from the range of 478-484 nm (such as about 480 nm).

[0029] The first light generating device further comprises a first luminescent material configured to convert a part of the first light source light into first luminescent material light. Hence, a part of the first light source remains unconverted and can be part of the first device light. The first device light thus comprises the first light source light and the first luminescent material light.

[0030] In particular embodiments, the first luminescent material comprises a phosphor having a full width at half maximum (FWHM) of at least 25 nm, such as at least 50 nm in embodiments, and having a peak wavelength selected from the range of 590-640 nm. Even more particularly, the first luminescent material can be configured to convert a part of the first light source light into first luminescent material light having a first luminescent material dominant wavelength λdL1 selected from the range of 575-638 nm. In embodiments, the first luminescent material dominant wavelength λdL1 is selected from the range of 575-630 nm. Even more particularly, the first luminescent material dominant wavelength λdL1 is selected from the range of 575-612 nm, such as about 577-605 nm, or even about 577-599 nm. In case the FWHM is larger than about 50 nm, the first luminescent material dominant wavelength λdL1 can in particular be lower than about 612 nm, while in case the FWHM is 30 nm or less, the first luminescent material dominant wavelength λdL1 can in particular be lower than about 638 nm. In embodiments, the first luminescent material dominant wavelength λdL1 can be obtained with a single luminescent material. In other embodiments, the first luminescent material dominant wavelength λdL1 can be obtained with two or more first luminescent materials, such as a plurality of different types of quantum dots. However, in particular embodiments, the first device light can substantially consist of a single type of first light source, such as a cyan LED, and a single type of first luminescent material.

[0031] Particularly good results can be obtained when the first dominant wavelength λd1 is selected from the range of 478-484 nm and wherein the first luminescent material dominant wavelength λdL1 is selected from the range of 575-638 nm, such as about 577-605 nm, even more particularly from the range of about 577-599 nm. This can provide the desired color point in a relatively energy efficient manner. To this end, for example, a divalent europium nitride containing (as an example shown below) can be applied. Alternatively or additionally, a tetravalent manganese doped fluoride, such as K2SiF6:Mn 4+ ) or a similar type of tetravalent manganese doped fluoride. It appears in particular that the combination of the first light source, such a first luminescent material and optionally one or more additional first luminescent materials, such as a cerium containing garnet type, can be very useful for providing the first light generating device.

[0032] The term "first light source" can also refer to a plurality of substantially identical first light sources, such as solid state light sources from a substantially identical batch. The term "first light source" can also refer to a plurality of different first light sources, although they all comply with the conditions indicated herein. The term "first luminescent material" can also refer to a plurality of different luminescent materials.

[0033] In particular, the first device light is white light based on a color point using the 10° color matching function.

[0034] Typically, color points and correlated color temperatures are defined based on the 2° color matching function, such as CIE 1931. From the website: https: / / www.konicaminolta.com / instruments / knowledge / color / part4 / 01.html The color sensitivity of the eye varies as a function of viewing angle (object size). CIE originally defined a standard observer in 1931 using a 2 field of view, hence the designation 2 standard observer. In 1964, CIE defined an additional standard observer, this time based on a 10° field of view; this is referred to as the 10 auxiliary standard observer. To give an idea of what a 2° field of view is compared to a 10° field of view, at a viewing distance of 50 cm, a 2° field of view would be a 1.7 cm circle, whereas a 10° field of view at the same distance would be an 8.8 cm circle. Color matching functions are tristimulus values of an equal-energy spectrum as a function of wavelength. These functions are intended to correspond to the sensitivity of the human eye. Separate sets of three color matching functions are specified for the 2° standard observer and the 10° auxiliary standard observer.

[0035] Hence, in this document CIE S 014-1 / E:2006 is used, see Table 1 and Table 2, respectively.

[0036] In view of the user perception, it seems more useful to define the color point of the first device light using the 10° color matching function. For comparing the color points of the first device light and the second device light, in this document the color point using the 10° color matching function is applied. Hence, for comparing these color points, both color points should be defined based on the 10° color matching function. For comparing the color points of the second device light and the third device light, in this document typically the color point using the 2° color matching function is applied. This also allows to provide a correlated color temperature.

[0037] Note that in specific embodiments the second device light and the third device light using the 2° color matching function is white light. Since the color point of the first device light and the second device light using the 10° color matching function is substantially the same (maximum difference of 0.03 for u' and / or 0.03 for v', such as maximum difference of 0.02 for u' and / or 0.02 for v', even more particularly maximum difference of 0.01 for u' and / or 0.01 for v', even more particularly maximum difference of 0.005 for u' and / or 0.005 for v'), in practice in embodiments the first device light is also white light and can be perceived as white light by a (10° auxiliary standard) observer.

[0038] In particular assuming the 2° color matching function, the term "white light" herein is known to the person skilled in the art. Herein especially relates to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2700 K and 6500 K. Further, in embodiments the correlated color temperature (CCT) is especially a color point within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

[0039] Hence, the second device light is especially (such) white light. As mentioned above, since the color point of the first device light and the second device light using the 10° color matching function is substantially the same, the first device light can also (in embodiments) be denoted as white light.

[0040] Further, the first device light has a first color point. In particular, in embodiments the color point is selected from the range of 0.18-0.24 for u' and 0.4-0.53 for v' (using the 10° CMF). More in particular, u' can be selected from the range of 0.19-0.23, such as 0.195-0.22, more in particular from the range of 0.195-0.205. More in particular, v' can be selected from the range of 0.41-0.52, more in particular from the range of 0.43-0.50, such as in particular from the range of 0.46-0.47 (using the 10° CMF). The former range is equal to about 20000-3500 K in the u'v' CIE diagram of 1976, for example.

[0041] Further, the first device light has a first correlated color temperature Tci. Hence, the first light generating device can be denoted as a cool white light generating device.

[0042] The first light generating device can further comprise a cyan LED as the pump LED. Hence, the first light generating device can also be denoted as a cyan LED or a cyan PC LED herein.

[0043] The second light generating device is configured to generate second device light.

[0044] In particular, the second light generating device comprises a second light source configured to generate second light source light having a second dominant wavelength λd2. The second light source especially comprises a solid state light source, such as an LED. In particular, the second dominant wavelength λd2 is smaller than the first dominant wavelength λd1. Hence, the first light source and the second light source especially belong to different bins. In embodiments, λd1- λd2≥ 10 nm.

[0045] In embodiments, the second light source can be configured to generate visible light, especially blue light. Hence, in embodiments, the second light source can in particular be configured to generate first light source light having a second dominant wavelength λd2 selected from the range of 430-470 nm, such as at least 430 nm, but at least smaller than the first dominant wavelength λd1 (see also above). In specific embodiments, λd2≤ 465 nm.

[0046] Alternatively or additionally, in embodiments, the second light source can be configured to generate light having an even shorter (dominant) wavelength. Hence, in embodiments, the second light source can in particular be configured to generate first light source light having a second dominant wavelength λd2 selected from the range of 380-430 nm.

[0047] The second light generating device further comprises a second luminescent material configured to convert at least part of the second light source light into second luminescent material light. Hence, at least part of the second light source light can remain unconverted and can be part of the second device light. Hence, the second device light comprises the second luminescent material light and optionally the second light source light. As mentioned above, there can be two main embodiments. In a first embodiment, the second light source can be configured to generate blue light. In such embodiments, one or more luminescent materials can be used to convert part of the second light source light into second luminescent material light. In a second embodiment, the second light source can be configured to generate light source light having a dominant wavelength below the (blue) wavelength range of 430-470 nm. In such embodiments, especially the light source light can be fully converted into luminescent material light. Hence, in such second embodiments, the second light generating device can in particular comprise two or more different luminescent materials.

[0048] The term "second light source" can also refer to a plurality of substantially identical second light sources, such as solid state light sources from substantially the same bin. The term "second light source" can also refer to a plurality of different second light sources, although they all comply with the conditions indicated herein. The term "second luminescent material" can also refer to a plurality of different luminescent materials.

[0049] In particular, the second device light is white light, as its color point is determined as x, y in the CIE 1931 color diagram (2° CMF), or as u'v' in the CIE 1976 color diagram (2° CMF), within 15 SDCM from the BBL, even more particularly within about 10 SDCM from the BBL.

[0050] Further, the second device light has a second color point. In particular, in embodiments, the second color point is selected from the range of 0.19-0.27 for u' and 0.42-0.54 for v' (in 2° CMF). More particularly, the second color point is selected from the range of 0.19-0.26 for u' and 0.43-0.53 for v' (in 2° CMF). The color point of the 2° CMF or 10° CMF can be substantially the same for the second device light. Thus, in embodiments, the second color point is selected from the range of about 0.19-0.27 for u' and about 0.42-0.54 for v' (in 10° CMF). More particularly, the second color point is selected from the range of about 0.19-0.26 for u' and about 0.43-0.53 for v' (in 10° CMF).

[0051] Further, the second device light can have a second correlated color temperature Tc2. In particular, in embodiments, the second correlated color temperature Tc2may be selected from the range of 2700-6500 K, in particular at least about 3000 K, even more particularly at least about 3300 K, such as at least 3400 K. More particularly, the second correlated color temperature Tc2may be at least 3500 K, such as even more particularly at least about 4000 K. In yet another particular embodiment, the second correlated color temperature Tc2may be selected from the range of at least 4500 K, such as at least 5000 K, like from the range of 5000-6500 K. Thus, the second light generating device can represent a cool white light generating device.

[0052] As mentioned above, the spectral power distributions of the first light source light and the second light source light are different. However, the color points can be substantially the same (based on 10° CMF). Thus, in embodiments, the first color point and the second color point can differ at most by 0.03 for u' and / or by 0.03 for v' (based on 10° CMF), such as at most by 0.01 for u' and / or by 0.01 for v', even more particularly at most by 0.005 for u' and / or by 0.005 for v' (based on 10° CMF).

[0053] Thus, in embodiments, the light generating system can comprise one or more first light generating devices and one or more second light generating devices, and no other types of light generating devices (which can contribute to the system light). Thus, in such embodiments, the system light can essentially consist of the first device light and the second device light. However, in specific embodiments, the light generating system can further comprise a system configured to control the system light. In such embodiments, the spectral power distribution of the system light can be controlled, e.g., by (e.g., individually) controlling the power to the first light generating devices and the second light generating devices. Thus, in such embodiments, the system light can essentially consist of the one or more first device light and the second device light.

[0054] The term "control" and similar terms refer, inter alia, to at least determining the behavior of an element or supervising the operation of an element. Thus, "control" and similar terms here can refer, for example, to imposing a behavior on an element (determining the behavior or supervising the operation of an element), etc., such as measuring, displaying, actuating, opening, displacing, changing a temperature, etc. In addition thereto, the term "control" and similar terms can additionally include monitoring. Thus, the term "control" and similar terms can include imposing a behavior on an element and imposing a behavior on an element and monitoring the element. The control of an element can be done with a control system, which can also be denoted as "controller". The control system and the element can thus be functionally coupled at least temporarily or permanently. The element can comprise the control system. In embodiments, the control system and the element can not be physically coupled. The control can be done by wired and / or wireless control. The term "control system" can also refer to a plurality of different control systems, which are functionally coupled, inter alia, and wherein, for example, one control system can be a master control system and one or more other control systems can be slave control systems. The control system can comprise or can be functionally coupled to a user interface.

[0055] The control system can also be configured to receive and execute instructions from a remote control. In embodiments, the control system can be controlled via an App on a device, such as a portable device (like a smart phone or I-phone, a tablet, etc.). Thus, the device does not necessarily have to be coupled to the lighting system, but can be (temporarily) functionally coupled to the lighting system.

[0056] Hence, in embodiments, the control system can (also) be configured to be controlled by an App on a remote device. In such embodiments, the control system of the lighting system can be a slave control system or be controlled in a slave mode. For example, the lighting system can be identifiable with a code, in particular a unique code for the respective lighting system. The control system of the lighting system can be configured to be controlled by an external control system that accesses the lighting system based on knowledge of the (unique) code (by optical sensor (such as a QR code reader) inputting the (unique) code via a user interface). The lighting system can also comprise means for communicating with other systems or devices, such as based on Bluetooth, WIFI, LiFi, ZigBee, BLE or WiMAX, or other wireless technologies.

[0057] A system, apparatus or device can perform an action in a "mode" or "operating mode" or "mode of operation". Likewise, in a method, an action or phase or step can be performed in a "mode" or "operating mode" or "mode of operation". The term "mode" can also be denoted as "control mode". This does not exclude that the system, apparatus or device can also be adapted to provide another control mode or a plurality of other control modes. Likewise, this can not exclude that one or more other modes can be performed before and / or after the performance of the mode.

[0058] However, in embodiments, the control system can be available that is adapted to provide at least a control mode. If other modes are available, the selection of such mode can be performed in particular via a user interface, although other options (such as performing a mode according to a sensor signal or a (time) scheme) are possible. In embodiments, the operating mode can also refer to a system, apparatus or device that is only capable of operating in a single operating mode (i.e. "on" without further tunability).

[0059] Hence, in embodiments, the control system can control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor) and a timer. The term "timer" can refer to a clock and / or a predetermined time scheme.

[0060] In yet another embodiment, the system can further comprise an input device selected from the group consisting of a user interface, a time device and a sensor, wherein the control system can in particular be configured to control the spectral power distribution of the system light in response to a signal of the input device.

[0061] The light generating system further comprises a third light generating device.

[0062] The third light generating device comprises a third light source configured to generate third light source light having a third dominant wavelength λd3. The third light source especially comprises a solid state light source, such as a LED. The third dominant wavelength λd3 is smaller than the first dominant wavelength λd1, and λd1- λd3≥ 10 nm. Hence, the first light source and the third light source especially belong to different bins.

[0063] In embodiments, the third light source can be configured to generate visible light, especially blue light. Hence, in embodiments, the third light source can especially be configured to generate first light source light having a third dominant wavelength λd3 selected from the range of 430-470 nm, such as at least 430 nm, but at least smaller than the first dominant wavelength λd1 (see also above). In specific embodiments, λd3≤ 465 nm.

[0064] Alternatively or additionally, in embodiments, the third light source can be configured to generate light having an even shorter (dominant) wavelength. Hence, in embodiments, the third light source can especially be configured to generate first light source light having a third dominant wavelength λd3 selected from the range of 380-430 nm.

[0065] The third light generating device further comprises a third luminescent material configured to convert at least part of the third light source light into third luminescent material light. Hence, at least part of the third light source light can remain unconverted and can be part of the third device light. Hence, the third device light comprises third luminescent material light and optionally third light source light. As mentioned above, there can be two main embodiments. In a first embodiment, the third light source can be configured to generate blue light. In such embodiments, one or more luminescent materials can be used to convert part of the third light source light into third luminescent material light. In a second embodiment, the third light source can be configured to generate light source light having a dominant wavelength below the (blue) wavelength range of 430-470 nm. In such embodiments, especially the light source light can be fully converted into luminescent material light. Hence, in such third embodiments, the third light generating device can especially comprise two or more different luminescent materials.

[0066] The term "third light source" can also refer to a plurality of substantially identical third light sources, such as solid state light sources from substantially identical bins. The term "third light source" can also refer to a plurality of different third light sources, although they all comply with the conditions indicated herein. The term "third luminescent material" can also refer to a plurality of different luminescent materials.

[0067] Especially, the third device light is white light.

[0068] Further, the third device light has a third color point. In particular, in embodiments the color point is selected from the range of 0.22-0.30 for u’ and 0.46-0.54 for v’ (using 2° CMF). More in particular, in embodiments the color point is selected from the range of 0.23-0.29 for u’ and 0.47-0.53 for v’ (using 2° CMF). The color point of the 2° CMF or 10° CMF is substantially the same for the third device light. Hence, in embodiments the color point is selected from the range of 0.22-0.30 for u’ and 0.46-0.54 for v’ (using 10° CMF). More in particular, in embodiments the color point is selected from the range of 0.23-0.29 for u’ and 0.47-0.53 for v’ (using 10° CMF).

[0069] It is assumed that the color point u’2 (u’ color coordinate of the second device light) based on the 2° CMF is smaller than u’3 (color coordinate of the third device light). In particular, u’3-u’2 > 0.01, in particular u’3-u’2 > 0.02, even more in particular u’3-u’2 > 0.03. Further, it is assumed that the color point v’2 (v’ color coordinate of the second device light) based on the 2° CMF can be smaller than v’3 (color coordinate of the third device light). In particular, v’3-v’2 > 0.01, in particular v’3-v’2 > 0.02, even more in particular v’3-v’2 > 0.03. In yet another particular embodiment, one or more (in particular both) of the following apply: u’3-u’2 > 0.04 and v’3-v’2 > 0.04.

[0070] Further, the device light has a third correlated color temperature Tc3. In particular, in embodiments the third correlated color temperature Tc3 is selected from the range of 2000-4000 K, such as in particular from the range of 2700-3500 K, such as up to about 3400 K.

[0071] In particular, Tc2-Tc3 > 700 K, even more in particular Tc2-Tc3 > 800 K, yet even more in particular Tc2-Tc3 > 1000 K. Further, in particular embodiments Tc2-Tc3 > 1300 K. As indicated above, the correlated color temperature is defined based on the 2° CMF, among others.

[0072] Hence, the third light generating device can represent a warm white light generating device.

[0073] As can be derived from the above, in embodiments the spectral power distribution of the first light source light and the third light source light are different.

[0074] Thus, in embodiments, the light generating system can comprise one or more first light generating devices, one or more second light generating devices and one or more third light generating devices, and no other type of light generating device (which can contribute to the system light). Thus, in such embodiments, the system light can essentially consist of the first device light, the second device light and the third device light. However, in specific embodiments, the light generating system can further comprise a system configured to control the system light (see also above). In such embodiments, the spectral power distribution of the system light can be controlled, e.g., by (e.g., individually) controlling the power to the first light generating devices, the second light generating devices and the third light generating devices. Thus, in such embodiments, the system light can essentially consist of one or more of the first device light, the second device light and the third device light.

[0075] Some further embodiments are described below.

[0076] In specific embodiments, the first light source light has a first dominant wavelength λdi selected from the range of 470-490 nm, the second light source light has a second dominant wavelength λd2 selected from the range of 390-470 nm, and the third light source light has a third dominant wavelength λd3 selected from the range of 390-470 nm. With such wavelengths, the system light can be provided in a relatively efficient manner.

[0077] The term "light source" can refer to a semiconductor light emitting device such as a light emitting diode (LED), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSEL), an edge emitting laser, or the like. The term "light source" can also refer to an organic light emitting diode such as a passive-matrix (PMOLED) or active-matrix (AMOLED). In particular embodiments, the light source comprises a solid state light source such as an LED or laser diode. In one embodiment, the light source comprises an LED (light emitting diode). The term LED can also refer to a plurality of LEDs. Furthermore, the term "light source" can also refer to a so-called chip-on-board (COB) light source in embodiments. The term "COB" especially refers to an LED chip in the form of a semiconductor chip that is neither encased nor connected but mounted directly onto a substrate such as a PCB. Thus, a plurality of semiconductor light sources can be configured on the same substrate. In embodiments, the COB is a plurality of LED chips that are configured together as a single lighting module. The term "light source" can also relate to a plurality of (substantially identical (or different)) light sources such as 2-2000 solid state light sources. In embodiments, the light source can comprise one or more micro-optical elements (micro-lens arrays) downstream of a single solid state light source such as an LED or downstream of a plurality of solid state light sources (i.e. shared by a plurality of LEDs, for example). In embodiments, the light source can comprise an LED with on-chip optics. In embodiments, the light source comprises a pixelated single LED (with or without optics) (providing on-chip beam steering in embodiments).

[0078] The phrase "different light sources" or "a plurality of different light sources" and similar phrases can refer to a plurality of solid state light sources selected from at least two different bins in embodiments. Likewise, the phrase "same light sources" or "a plurality of same light sources" and similar phrases can refer to a plurality of solid state light sources selected from the same bin in embodiments.

[0079] In particular embodiments, each phosphor comprised in the luminescent material (210, 220, 230) is configured to provide an emission, each phosphor having a full width at half maximum of at least 25 nm. For example, one or more of the first luminescent material, the second luminescent material, and the third luminescent material can comprise quantum dots.

[0080] In other embodiments, the second luminescent material and / or the third luminescent material comprises a phosphor configured to provide luminescent material light (221, 231) having a full width at half maximum of at least 40 nm. Thus, in embodiments, the second luminescent material light can have a FWHM of at least 40 nm. Alternatively or in addition, in embodiments, the third luminescent material light can have a FWHM of at least 40 nm.

[0081] In embodiments, the second luminescent material comprises one or more of a cerium containing garnet type luminescent material and a divalent europium based nitride material. In particular, the second luminescent material can comprise both. Alternatively or additionally, in embodiments, the third luminescent material comprises one or more of a cerium containing garnet type luminescent material and a divalent europium based nitride material. In particular, the third luminescent material can comprise both. In further embodiments, the third luminescent material can (additionally) comprise a Mn 4+ based narrow-band red emitting phosphor.

[0082] When luminescent materials are applied herein, the luminescent materials are especially configured downstream of a light source, such as the white light emitting solid state light source in the above embodiments. Hence, in embodiments, the light source can be configured upstream of the luminescent material, wherein the luminescent material is configured to convert at least part of the light source light. The terms "upstream" and "downstream" relate to the arrangement of items or features with respect to the propagation of light from a light generating device (here especially a light source), wherein a second position within the light beam closer to the light generating device is "upstream" and a third position within the light beam further away from the light generating device is "downstream" with respect to a first position within the light beam from the light generating device.

[0083] For green, yellow, orange and / or red emitting luminescent materials (e.g. inorganic luminescent materials with an activator or active species can be applied). Relevant active species can be for example Eu 2+ or Ce 3+ . Other active species can be quantum dots. Other active species can be organic luminescent dyes.

[0084] In embodiments, the luminescent material can be selected from garnets and nitrides, in particular doped with trivalent cerium or divalent europium, respectively. Embodiments of garnets especially comprise A3B5O 12 garnets, wherein A comprises at least yttrium or lutetium, and wherein B comprises at least aluminum. Such garnets can be doped with cerium (Ce), praseodymium (Pr) or a combination of cerium and praseodymium; in particular with Ce. In particular, B comprises aluminum (Al), however, B can also partially comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), in particular up to about 20% of Al, more in particular up to about 10% of Al (i.e. the B ions essentially consist of 90 mole% or more of Al and 10 mole% or less of one or more of Ga, Sc and In); B can in particular comprise up to about 10% of gallium. In another variant, B and O can be at least partially replaced by Si and N. The element A can especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and / or Tb are in particular only present in an amount of up to about 20% of A. In one particular embodiment, the garnet luminescent material comprises (Y 1-x Lu x )3B5O12 :Ce: wherein x is equal to or larger than 0 and equal to or smaller than 1.

[0085] The term ":Ce" indicates that part of the metal ions in the luminescent material (i.e. in garnets: part of the "A" ions) is replaced by Ce. For example, in (Y 1-x Lu x )3Al5O 12 :Ce: part of the Y and / or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will generally not replace more than 10% of the A; typically, the Ce concentration is in the range of 0.1-4%, in particular 0.1-2% (relative to A). Assuming 1% Ce and 10% Y, the correct formula can be (Y 0.1 Lu 0.89 Ce 0.01 )3Al5O 12 .

[0086] As is known to the person skilled in the art, Ce in garnets is essentially or only in the trivalent state.

[0087] In embodiments, the red luminescent material can 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 essentially or only divalent and replaces one or more of the indicated divalent cations. Typically, Eu will not be present in an amount larger than 10% of the cations; its presence is in particular in the range of about 0.5-10%, more in particular in the range of about 0.5-5% relative to the cations it replaces. The term ":Eu" indicates that part of the metal ions is replaced by Eu 2+ (e.g. in these embodiments by Eu 2+ ). For example, assuming 2% Eu in CaAlSiN3:Eu, the correct formula can be (Ca 0.98 Eu 0.02 )AlSiN3. The divalent europium typically replaces a divalent cation, such as the above-mentioned divalent alkaline earth cations, in particular Ca, Sr or Ba.

[0088] The material (Ba,Sr,Ca)S:Eu can also be denoted as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M comprises calcium or strontium, or calcium and strontium, in this compound, more in particular calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr and Ca).

[0089] Furthermore, the material (Ba,Sr,Ca)2Si5N8:Eu can also be denoted as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M comprises Sr and / or Ba in this compound. In another particular embodiment, M consists of Sr and / or Ba (not considering the presence of Eu), in particular 50-100%, more in particular 50-90% of Ba and 50-0%, in particular 50-10% of Sr, such as Ba 1.5 Sr 0.5 Si5N8:Eu (i.e. 75% Ba; 25% Sr). Here, Eu is incorporated and replaces at least part of M, i.e. one or more of Ba, Sr and Ca.

[0090] Likewise, the material (Ba,Sr,Ca)AlSiN3:Eu can also be denoted as MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M comprises calcium or strontium, or calcium and strontium, more in particular calcium in this compound. Here, Eu is incorporated and replaces at least part of M, i.e. one or more of Ba, Sr and Ca.

[0091] As is known to the person skilled in the art, Eu in the above luminescent materials is essentially or only in the divalent state.

[0092] Garnet-type luminescent materials can in particular be used as second and / or third luminescent material.

[0093] The term "luminescent material" herein in particular relates to inorganic luminescent materials, which are sometimes also denoted as phosphors. These terms are known to the person skilled in the art.

[0094] The term "light emitting material" especially refers to a material which can convert a first radiation, especially one or more of UV radiation and blue radiation, into a second radiation. Typically, the first and second radiation have a different spectral power distribution. Instead of the term "light emitting material", also the term "light emission converter" or "converter" can be applied. Typically, the second radiation has a spectral power distribution at a larger wavelength than the first radiation, which is the case in so-called down-conversion. However, in specific embodiments, the second radiation has a spectral power distribution of intensity at a smaller wavelength than the first radiation, which is the case in so-called up-conversion. In embodiments, the "light emitting material" can especially refer to a material which can convert radiation into e.g. visible light and / or infrared light. For example, in embodiments, the light emitting material is capable of converting one or more of UV radiation and blue radiation into visible light. In specific embodiments, the light emitting material can also convert radiation into infrared radiation (IR). Thus, upon excitation with radiation, the light emitting material emits radiation. Typically, the light emitting material will be a down-converter, i.e. a smaller wavelength radiation is converted into a radiation having a larger wavelength (λ ex <λ em ), although in specific embodiments, the light emitting material can comprise an up-converter light emitting material, i.e. a larger wavelength radiation is converted into a radiation having a smaller wavelength (λ ex >λ em ). In embodiments, the term "light emitting" can refer to phosphorescence. In embodiments, the term "light emitting" can also refer to fluorescence. Instead of the term "light emitting", also the term "emitting" can be applied. Thus, the terms "first radiation" and "second radiation" can refer to excitation radiation and emission (radiation), respectively. Likewise, the term "light emitting material" can in embodiments refer to phosphorescence and / or fluorescence. The term "light emitting material" can also refer to a plurality of different light emitting materials.

[0095] As mentioned above, in specific embodiments, the light generating system can optionally further comprise a control system configured to control the first light generating device and the second light generating device. As the system can further comprise a third light generating device, in specific embodiments, the light generating system can further comprise a control system configured to control the first light generating device, the second light generating device and the third light generating device. In particular, in embodiments, the control system can be configured to individually control two or more of the first light generating device, the second light generating device and the third light generating device. In this way, the spectral power distribution can be controlled and at the same time the MDER value can be controlled.

[0096] Further, using the solution of the present application, the color difference between the cyan-based light source and the second light generating device is substantially eliminated, as both can substantially emit device light having substantially the same color point (using the 10° CMF). Hence, the present application also allows for a simplification in the sense that the first light generating device and the second light generating device are controlled as a group. Hence, in a particular embodiment, the control system can be configured to individually control (a) the group comprising the first light generating device and the second light generating device, and (b) the third light generating device.

[0097] For example, this can also allow for the first light generating device and the second light generating device to be arranged in a first string, and the third light generating device to be arranged in a second string.

[0098] Hence, the light generating system comprises (i) a first LED string comprising one or more first light generating devices and one or more second light generating devices, and (ii) a second LED string comprising one or more third light generating devices.

[0099] As indicated above, in particular, the light source (10, 20, 30) comprises a solid state light source.

[0100] In particular, in embodiments, the number of first light generating devices n1 plus the number of second light generating devices n2 can be substantially the same as the number of third light generating devices n3. Hence, in a particular embodiment, (n1 + n2) / n3 = 1. The number of first light generating devices n1 plus the number of second light generating devices n2 in the first string can then be chosen depending on, for example, the type of application. In particular, in embodiments, the ratio of (a) the number of first light generating devices n1 and (b) the number of second light generating devices n2 is 0.05 < n1 / n2 < 20, although other values are possible as well.

[0101] Note that in a particular embodiment, the term "first string" can also refer to a plurality of first strings arranged electrically in parallel. Note that in a particular embodiment, the term "second string" can also refer to a plurality of second strings arranged electrically in parallel.

[0102] With the present application, the system light can be provided with a relatively high MDER. Further, this can be provided in a way that the color difference between the white LED and the cyan LED can not be an issue (see also above).

[0103] With respect to the MDER value, in the operational mode of the light generating system, the system light can have an MDER value selected from the range of at least 0.45, even more particularly at least 0.65, wherein MDER is defined as:

[0104]

[0105] where SPD( ) is the spectral power distribution of the system light, m( ) is the black- vision sensitivity function, and V( ) is the photopic luminosity function.

[0106] Further, in particular embodiments, in the operational mode of the light generating system, the system light can have a CRI of at least 80. Further, in particular embodiments, in the operational mode of the light generating system, the system light can have an R9 value of at least 50. Hence, in particular embodiments, in the operational mode of the light generating system, the system light can have an MDER of at least 0.45, a CRI of at least 80 (such as at least 85) and an R9 of at least 50. In particular, the system light can have an MDER of at least 0.65.

[0107] For example, in embodiments, the control system can be configured to control the spectral power distribution of the system light in the operational mode while maintaining a predefined MDER value. The term "predefined MDER value" can refer to a value or a range of values. In particular, it can refer to a subset of MDER with a range of 0.45-1.3 (such as in the range of 0.65-0.89). MDER values larger than 1.3 are also possible, but this can result in a less desirable CRI.

[0108] As mentioned above, in embodiments, the light generating system can further comprise an input device selected from the group consisting of a user interface, a time device and a sensor. In particular, the control system (see also above) can be configured to control the spectral power distribution of the system light in response to a signal of the input device. For example, at higher daylight levels, the system light can be reduced. For example, later in the day (such as in the evening), the MDER value can be decreased. In embodiments, the MDER value can depend on the daylight level (and / or the time of day). Other embodiments are also possible. Hence, in particular, the control system can be configured to control the spectral power distribution of the system light of a light generating system (such as a light generating system), wherein the system comprises (i) a first LED string comprising one or more first light generating devices and one or more second light generating devices, and (ii) a second LED string comprising one or more third light generating devices, such as in embodiments, the light generating system comprises (i) a first LED string comprising one or more first light generating devices and one or more second light generating devices, and (ii) a second LED string comprising one or more third light generating devices.

[0109] In yet another aspect, the application provides a luminaire or lighting device comprising a light generating system as defined herein. The lighting device can further comprise a housing, optical elements, louvres, etc. The luminaire or lighting device can comprise a housing encapsulating the first light generating device, the second light generating device and optionally the third light generating device. The luminaire or lighting device can comprise a light window in the housing or a housing opening through which the system light can escape from the housing.

[0110] The light generating system can for example be part of or can be applied in an office lighting system, a home application system, a shop lighting system, a home lighting system, a spot lighting system, a spotlight lighting system, a theater lighting system, a fiber application system, a projection system, a self-lit display system, a pixelated display system, a segmented display system, a warning sign system, a medical lighting application system, an indication sign system, a decorative lighting system, a portable system, a car application, an (outdoor) road lighting system, a city lighting system, a greenhouse lighting system, horticulture lighting, digital projection or LCD backlighting.

[0111] The term "blue light" or "blue emission" relates especially to light having a wavelength in the range of about 440-495 nm (including some violet and cyan hues). The term "green light" or "green emission" relates especially to light having a wavelength in the range of about 495-570 nm. The term "yellow light" or "yellow emission" relates especially to light having a wavelength in the range of about 570-590 nm. The term "orange light" or "orange emission" relates especially to light having a wavelength in the range of about 590-620 nm. The term "red light" or "red emission" relates especially to light having a wavelength in the range of about 620-780 nm. The term "pink light" or "pink emission" refers to light having a blue and a red component.

[0112] The term "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. BRIEF DESCRIPTION OF DRAWINGS

[0113] Embodiments of the application 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:

[0114] Figure 1 Spectral power distributions (normalized) of embodiments of the first device light 111, the second device light 121 and the third device light 131 are shown;

[0115] Figure 2 Embodiments of a light generating device comprising two LED strings are schematically depicted;

[0116] Figure 3 The shift in the spectral power distribution is shown as a function of the different number of first and second light generating devices in one of the strings;

[0117] Figure 4 The results are shown, where the shading represents the efficiency of the power balanced lighting device (4400 lumen, LOR = 0.9, 4000 K) as a function of the number of cyan-red LEDs in the cool white channel (horizontal axis) and the flux under reference conditions of the cyan-red LEDs (left vertical axis); the labels at the bottom give the corresponding red phosphor used for the cyan-red LEDs (see Table 1). The white dots represent the cases where the CRI is larger than 80. The data labels give the black body-DER, CRI and R9.

[0118] Figs. 5a-5d schematically depict a number of embodiments;

[0119] Figure 6 The relative black body (m) (i.e. m(λ)) and V(λ) human eye sensitivity functions are shown; and

[0120] Figure 7 The 2° and 10° color matching functions are provided (such as derived from CIE S 014-1 / E:2006).

[0121] The schematic drawings are not necessarily to scale. DETAILED DESCRIPTION

[0122] In an embodiment, the direct cyan emitters can be replaced by cyan-pumped phosphor converted LEDs. A combination of cyan and red phosphor can be used to generate a cool white color point (e.g. 6500 K). These LEDs can then be used in a 2-channel tunable system. For example, the system can use warm white LEDs in one string, while in the second string a combination of cyan-pumped LEDs and cool white LEDs is used. In particular, the color points of the cool white LEDs and the cyan-pumped LEDs can be substantially the same. The two cool white LEDs are very different in the spectrum (see Figure 1 ), resulting in a CRI difference > 60, for example. However, since the color points can be substantially the same, they can look the same when viewing them in the on state, and even when combined with a lens, can not give a color shadow. Since the two types of LEDs in the cyan-enhanced string can have substantially the same color point, the cyan content in the final spectrum can be adjusted more freely (e.g. 0-12 LEDs can be changed in steps of 1, without problems of color non-uniformity; see Figures 2-3 ) It is noted that it is not necessary to apply 12 LEDs. Other numbers are possible as well.

[0123] REFERENCE Figure 1In embodiments, the first light source light 11 can have a first dominant wavelength λdi selected from the range of 470-490 nm. Further, the second light source light 21 can have a second dominant wavelength λd2selected from the range of 390-470 nm. Further, the third light source light 31 can have a third dominant wavelength λd3selected from the range of 390-470 nm. Also as shown, in these embodiments, each luminescent material comprises a phosphor, each phosphor configured to provide an emission having a full width at half maximum of at least 25 nm. In particular embodiments, the second and third luminescent materials comprise a phosphor configured to provide luminescent material light 221, 231 having a full width at half maximum of at least 40 nm. The third luminescent material can comprise a narrow-band red-emitting phosphor based on Mn 4+ . However, the second luminescent material can also comprise a narrow-band red-emitting phosphor based on Mn 4+ . Further, in particular embodiments, the first luminescent material can also comprise a narrow-band red-emitting phosphor based on Mn 4+ . However, in embodiments, the first, second and third luminescent materials can comprise at least two different material compositions. This can involve different weight ratios and / or different types of luminescent materials.

[0124] Figure 2 Embodiments depicting possible combinations of strings are schematically shown.

[0125] In particular embodiments, see also Figure 2 , the light generating system 1000 can comprise (i) a first LED string 2100 comprising one or more first light generating devices 110 and one or more second light generating devices 120, and (ii) a second LED string 2200 comprising one or more third light generating devices 130, wherein the light source comprises a solid state light source. In embodiments, in one of the strings, the ratio of the number of first light generating devices 110 nl to the number of second light generating devices 120 n2 can be 0.05 < nl / n2 < 20. In these embodiments, both strings have k light generating devices. Hence, in these embodiments, k-nl=n2 second light generating devices 120. The second string 2200 has k third light generating devices 130.

[0126] The performance of a tunable system is calculated using different LED combinations. The warm white LEDs used in these cases have a CRI > 90 and a CCT of 3000 K. Figure 3 Different spectra achievable for different nl / n2 for the same LED type are shown (i.e. 1 cyan DWL-red phosphor combination for the light generating devices 110; see also Figure 1 ).

[0127] Several combinations of cyan DWL (dominant wavelength) and red phosphor were used in the calculations. The choice of DWL and thickness of the cyan LED (i.e. the degree of conversion of the red phosphor) was adjusted to the choice of red phosphor in order to keep close to the 6500K point on the BBL (here defined using the 10° CMF).

[0128] The performance of several different LED combinations was evaluated with the above method, in particular by making cyan-enhanced 6500K LEDs with different cyan DWL-red phosphor combinations: cyan DWL 486, 487 and 489 nm with red phosphor PP 611, 620, 628 and 639 nm, respectively. Here, DWL stands for dominant wavelength and PP for peak position. It appeared that among others, a system with CRI > 80 and a black- vision-DER > 1 at 5000K and a system with CRI > 80 and MDER ~ 0.9 at 4200K were feasible.

[0129] The performance of different options was calculated. Using longer DWL cyan LEDs can require a deeper red phosphor to aim at the BBL. In principle, longer wavelength cyan LEDs fit the black- vision stimulus curve better. Note that the amount of cyan light in the cyan-red spectrum is significantly reduced because we need to generate more red light to aim at "white" light. These different cyan LEDs were used in a tunable system. The efficiency was calculated as a function of CCT and the number of cyan-red LEDs in the cool white string (total length = 12). The shorter the peak wavelength of the red phosphor in the cyan LED, the better the efficiency of the system (as expected). Surprisingly, the MDER of the system is essentially independent of the choice of cyan-red phosphor combination Figure 4 ). For the black- vision-DER, the choice of cyan-red LEDs can be less important, and for the system efficiency, it is best to choose the shortest red phosphor (and shorter DWL cyan LED) possible.

[0130] Thus, combining a cyan pump LED and a blue pump LED having the same color as the second channel can allow to produce a tunable system with a large tuning range.

[0131] In Figure 4 , the shading represents the efficiency of a power balanced lighting device (4400 lumen, LOR = 0.9, 4000K) as a function of the number N of cyan-red LEDs in the cool white channel (vertical axis) and the flux (F) in the reference condition of the cyan-red LEDs (top horizontal axis); the labels at the bottom give the corresponding red phosphor used for the cyan-red LEDs, as shown in the table below. The peak position decreases from left to right. The white dots represent the cases where the CRI is greater than 80. The data labels give the black- vision-DER, CRI and R9.

[0132]

[0133] Of course, for the requirement of CRI > 80, in the CCT region of interest (3000-5000K), the maximum MDER values can be achieved with all cyan DWL-red phosphor combinations. But the LED efficiency is different. The 480nm-611nm combination can provide the highest efficiency.

[0134] It is known from perception tests that the use of a 10° CMF matches better with the color point.

[0135] The application can also be used for light sources aimed at static high black view stimulus. Then, for this static solution, the cyan-pumped white LED color point should aim at the same color point of the white LED, most likely more likely around 4000K.

[0136] The application also provides a white light light source with tunable black view stimulus (i.e. high MDER at high CCT and low / normal MDER at low CCT) by combining a string of warm white LEDs (string 1) and a second string consisting of cyan-pumped LEDs combined with (blue-pumped) cool white LEDs, wherein: (a) the color points of the two LEDs in the cool white string are substantially the same; and (b) in particular embodiments, the number of cyan-pumped LEDs / strings can be e.g. > 0 and < 8. Moreover, in particular (c) the CRI difference between the cyan-pumped LEDs and the cool white LEDs is > 60.

[0137] Fig. 5a schematically depicts an embodiment of a light generating system 1000 configured to generate a system light 1001. The light generating system 1000 comprises a first light generating device 110 and a second light generating device 120.

[0138] The first light generating device 110 is configured to generate a first device light 111. The first light generating device 110 comprises a first light source 10 configured to generate first light source light 11 having a first dominant wavelength d1 (e.g. selected from the range of 470-500 nm), and a first luminescent material 210 configured to convert a part of the first light source light 11 into first luminescent material light 211.

[0139] The first device light 111 comprises the first light source light 11 and the first luminescent material light 211.

[0140] In particular, the first device light 111 can be white light. Moreover, the first device light 111 has a first color point. Furthermore, the first device light 111 can have a first correlated color temperature Tc1.

[0141] The first light generating device can in particular be a cyan PC LED providing a cool white color.

[0142] The second light generating device 120 is configured to generate second device light 121. The second light generating device 120 comprises a second light source 20 configured to generate second light source light 21 having a second dominant wavelength d2, and a second luminescent material 220 configured to convert at least part of the second light source light 21 into second luminescent material light 221. The second device light 121 comprises the second luminescent material light 221 and optionally the second light source light 21.

[0143] In particular, the second device light 121 can be white light. The second device light 121 has a second color point. The second device light 121 can have a second correlated color temperature Tc2.

[0144] In particular, d1-d2≥ 10 nm. In embodiments, d2≤ 465 nm.

[0145] Also as Figure 1 indicated, the spectral power distributions of the first light source light 11 and the second light source light 21 are different.

[0146] In particular, the first color point and the second color point have a maximum difference of 0.03 for u’ and / or a maximum difference of 0.03 for v’ (such as a maximum difference of 0.01 for u’ and / or a maximum difference of 0.01 for v’), in particular using the 10° color matching functions according to CIE S014-1 / E:2006, see Table 2.

[0147] The second light generating device in particular comprises a PC LED comprising a blue solid state light source (pump) configured to provide cool white light.

[0148] In embodiments, also referring to Figure 1 , the first dominant wavelength d1 is selected from the range of 478-484 nm. In embodiments, also referring to Figure 1 , the first luminescent material 210 is configured to convert part of the first light source light 11 into first luminescent material light 211 having a first luminescent material dominant wavelength dL1 selected from the range of 575-638 nm.

[0149] The illumination system light 1001 can in the operational mode in particular comprise the first device light 111 and the second device light 121. Hence, the illumination system light 1001 can in the operational mode in particular comprise the first light source light 11, the first luminescent material light 211, the second light source light 21 and the second luminescent material light 221.

[0150] Fig. 5b schematically depicts an embodiment of the light generating system 1000 further comprising a third light generating device 130.

[0151] The third light generating device 130 is configured to generate third device light 131. The third light generating device 130 comprises a third light source 30 configured to generate third light source light 31 having a third dominant wavelength λd3, and a third luminescent material 230 configured to convert at least part of the third light source light 31 into third luminescent material light 231.

[0152] The third device light 131 comprises the third luminescent material light 231 and optionally the third light source light 31.

[0153] The third device light 131 can be white light. The third device light 131 has a third color point. The third device light 131 can have a third correlated color temperature Tc3.

[0154] In particular, in embodiments λd1-λd3≥ 10 nm. In particular embodiments, λd3≤ 465 nm.

[0155] It can further be seen from Figure 1 that the spectral power distributions of the first light source light 11 and the third light source light 31 are different.

[0156] In particular, the system light 1001 comprises one or more of the first device light 111, the second device light 121 and the third device light 131.

[0157] The illumination system light 1001 can in an operational mode comprise in particular all of the first device light 111, the second device light 121 and the third device light 131. Hence, the illumination system light 1001 can in an operational mode comprise in particular the first light source light 11, the first luminescent material light 211, the second light source light 21, the second luminescent material light 221, the third light source light 31 and the third luminescent material light 231. However, other embodiments are possible as well.

[0158] In particular embodiments, Tc2-Tc3≥ 1000 K.

[0159] The third light generating device comprises in particular a PC LED comprising a blue solid state light source (pump) configured to provide warm white light.

[0160] As schematically shown in Fig. 5c, the light generating system 1000 can further comprise a control system 300 configured to control the first light generating device 110, the second light generating device 120 and optionally the third light generating device 130.

[0161] In embodiments, the control system 300 can be configured to control (a) the group comprising the first light generating device 110 and the second light generating device 120, and (b) the third light generating device 130, separately; see also Figure 2 .

[0162] The light generating system 1000 can further comprise an input device 350 selected from the group consisting of a user interface 351, a time device 352 and one or more sensors 353.

[0163] The control system can in particular be configured to control the spectral power distribution of the system light 1001 in response to a signal of the input device 350.

[0164] Fig. 5d schematically depicts an embodiment of a luminaire 1 (embodiment I) or lighting device 2 (embodiment II) comprising a light generating system 1000. In embodiment II, reference L denotes a light blocking grid. However, other embodiments are of course also possible.

[0165] Figure 6 The relative photopic (m) (i.e. m( )) and scotopic (V( )) human eye sensitivity functions are shown. The maximum sensitivity of the scotopic function is at 490 nm, the full width at half maximum values are 447 nm and 531 nm. See also the accompanying table for the scotopic and photopic human eye sensitivity functions:

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177]

[0178] Figure 7 2° and 10° color matching functions are provided (such as derived from CIE S 014-1 / E:2006).

[0179] The term "plurality" means two or more.

[0180] The terms "substantially" or "essentially" and similar terms in the present text will be understood by the skilled person. The terms "substantially" or "essentially" can also include embodiments with "entirely", "completely", "all" and the like. Thus, in embodiments, the adjective "substantially" or "essentially" can also be removed. Where applicable, the term "substantially" or the term "essentially" can also relate to 90% or more, such as 95% or more, especially 99% or more, even more especially 99.5% or more, including 100%.

[0181] The term "comprising" also includes embodiments in which the term "comprising" is interpreted as "consisting of".

[0182] The term "and / or" relates especially to one or more of the items preceding and following "and / or". For example, the phrase "item 1 and / or item 2" and similar phrases can relate to one or more of item 1 and item 2. The term "comprising" can in one embodiment mean "consisting of", but can in another embodiment also mean "containing at least the defined substance and optionally one or more other substances".

[0183] 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 application described herein are capable of operation in other sequences than described or illustrated herein.

[0184] These devices, apparatus or systems can especially be described herein during operation. It will be clear to a person skilled in the art that the application is not limited to methods of operation, or devices, apparatus or systems in operation.

[0185] It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0186] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0187] The use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in the claims. Unless otherwise defined, all terminology used herein, including words and phrases other than in the claims, is intended to be interpreted in accordance with the ordinary meaning of such terms under the given circumstances (e.g., dictionary definitions, the meaning used in treaties, laws, regulations from the European Union and the United States Patent and Trademark Office, assignment practices, established case law by courts of general jurisdiction and other suitable dictionary, treatise, or treatise

[0188] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0189] The application can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim or claims or system claim or claims enumerating several means, several of these means can be embodied by one and the same item of hardware.

[0190] The application also provides a control system, which can control a device, an apparatus or a system, or which can carry out a method or process as described herein. Furthermore, the application also provides a computer program product, which, when running on a computer functionally coupled to or comprised by a device, an apparatus or a system, controls one or more controllable elements of such device, apparatus or system.

[0191] The application also applies to a device, apparatus or system comprising one or more characterising features described in the description and / or shown in the attached drawings. The application further relates to a method or process comprising one or more characterising features described in the description and / or shown in the attached drawings.

[0192] The various aspects discussed in this patent can be combined to facilitate providing additional advantages. Furthermore, those skilled in the art will appreciate that embodiments can be combined and that more than two embodiments can also be combined. Moreover, some features can form the basis of one or more divisional applications.

Claims

1. A light generating system (1000) configured to generate system light (1001), wherein the light generating system (1000) comprises a first light generating device (110) and a second light generating device (120), wherein: the first light generating device (110) is configured to generate first device light (111), wherein the first light generating device (110) comprises (i) a first light source (10) configured to generate first light source light (11) having a first dominant wavelength λdi selected from the range of 470-500 nm, and (ii) a first luminescent material (210) configured to convert a portion of the first light source light (11) into first luminescent material light (211); wherein the first device light (111) comprises the first light source light (11) and the first luminescent material light (211); and wherein the first device light (111) has a first color point; the second light generating device (120) is configured to generate second device light (121), wherein the second light generating device (120) comprises (i) a second light source (20) configured to generate second light source light (21) having a second dominant wavelength λd2, and (ii) a second luminescent material (220) configured to convert at least a portion of the second light source light (21) into second luminescent material light (221); wherein the second device light (121) comprises the second luminescent material light (221) and optionally the second light source light (21); and wherein the second device light (121) is white light having a second color point and a second correlated color temperature Tc2; λdi - λd2≥ 10 nm; the spectral power distributions of the first light source light (11) and the second light source light (21) are different; and the first color point and the second color point have a maximum difference of 0.03 for u’ and / or 0.03 for v’, wherein the color points are based on the 10° color matching functions, the light generating system (1000) further comprising a third light generating device (130), wherein: the third light generating device (130) is configured to generate third device light (131), wherein the third light generating device (130) comprises (i) a third light source (30) configured to generate third light source light (31) having a third dominant wavelength λd3, and (ii) a third luminescent material (230) configured to convert at least a portion of the third light source light (31) into third luminescent material light (231); wherein the third device light (131) comprises the third luminescent material light (231) and optionally the third light source light (31); and wherein the third device light (131) is white light having a third color point and a third correlated color temperature Tc3; λdi - λd3≥ 10 nm; the spectral power distributions of the first light source light (11) and the third light source light (31) are different; and the first color point and the third color point have a maximum difference of 0.03 for u’ and / or 0.03 for v’, wherein the color points are based on the 10° color matching functions. the system light (1001) comprises one or more of the first device light (111), the second device light (121) and the third device light (131); and Tc2-Tc3≥ 700 K, and the light generating system (1000) further comprises (i) a first string (2100) comprising one or more first light generating devices (110) and one or more second light generating devices (120) and (ii) a second string (2200) comprising one or more third light generating devices (130), wherein the light sources (10, 20, 30) comprise solid state light sources.

2. The light generating system (1000) according to claim 1, wherein the first luminescent material (210) is configured to convert a part of the first light source light (11) into first luminescent material light (211) having a first luminescent material dominant wavelength λdL1 selected from a range of 575 nm to 638 nm, and wherein the second correlated color temperature Tc2 of the second device light (121) is at least 3400 K.

3. The light generating system (1000) according to any one of the preceding claims, wherein the first dominant wavelength λd1 is selected from a range of 478 nm to 484 nm, and wherein the first luminescent material (210) is configured to convert a part of the first light source light (11) into first luminescent material light (211) having a first luminescent material dominant wavelength λdL1 selected from a range of 575 nm to 612 nm.

4. The light generating system (1000) according to claim 1 or 2, comprising a first LED string (2100) comprising one or more first light generating devices (110) and one or more second light generating devices (120), the first LED string (2100) having a ratio of (a) the number of first light generating devices (110) n1 to (b) the number of second light generating devices (120) n2, the ratio being 0.05 < n1 / n2 < 20, and wherein the light sources (10, 20) comprise solid state light sources.

5. The light generating system (1000) according to claim 1 or 2, wherein the second dominant wavelength λd2 is selected from a range of 430 nm to 470 nm.

6. The light generating system (1000) according to claim 1, wherein the second luminescent material (220) and the third luminescent material (230) comprise a phosphor configured to provide luminescent material light (221, 231) having a full width at half maximum of at least 40 nm, wherein Tc2-Tc3≥ 2500 K, and wherein the maximum difference in u’ of the first color point and the second color point is 0.01 and / or the maximum difference in v’ of the first color point and the second color point is 0.

01.

7. The light generating system (1000) according to claim 5, wherein the third luminescent material (230) comprises a narrow-band red emitting phosphor based on Mn 4 + .

8. The light generating system (1000) according to claim 5, further comprising a control system (300) configured to control one or more of the first light generating device (110), the second light generating device (120) and the third light generating device (130).

9. The light generating system (1000) according to claim 8, wherein the control system (300) is configured to individually control (a) a group comprising the first light generating device (110) and the second light generating device (120), and (b) the third light generating device (130).

10. The light generating system (1000) according to claim 5, wherein Tc2 - Tc3 > 1000 K.

11. The light generating system (1000) according to claim 4, further comprising an input device (350) selected from the group consisting of a user interface (351), a time device (352) and a sensor (353), wherein the control system (300) according to any one of the preceding claims 8-9 is configured to control the spectral power distribution of the system light (1001) in response to a signal of the input device (350).

12. The light generating system (1000) according to claim 11, wherein the control system (300) is configured to control the spectral power distribution of the system light (1001) of the light generating system (1000) as claimed in any one of the preceding claims 9-11.

13. The light generating system (1000) according to any one of claims 1, 2 and 6-12, wherein in an operational mode of the light generating system (1000), the system light (1001) has a CRI of at least 80, an R9 value of at least 50 and an MDER value selected from the range of at least 0.45, wherein MDER is defined as: MDER = 100 * (1 - (1 / (1 + (SPD(λ) * m(λ) * V(λ))))) wherein SPD(λ) is the spectral power distribution of the system light (1001), m(λ) is the black visibility sensitivity function, V(λ) is the photopic luminosity function.

14. The light generating system (1000) according to any one of the preceding claims 8-12, wherein control system (300) is configured to control the spectral power distribution of the system light (1001) in an operational mode while maintaining the MDER value as predefined in claim 13.

15. A luminaire (1) or lighting device (2) comprising a light generating system (1000) according to any one of the preceding claims. ​

Images