Black light system with high cri using cyan direct emitters

Abstract

The invention provides a light generating system (1000) comprising one or more first light generating devices (110), one or more second light generating devices (120) and one or more third light generating devices (130), wherein: the one or more first light generating devices (110) are configured to generate white first device light (111) having a first color rendering index CRI1 and a first correlated color temperature Tc1; the one or more second light generating devices (120) are configured to generate white second device light (121) having a second color rendering index CRI2 and a second correlated color temperature Tc2; the one or more third light generating devices (130) are configured to generate third device light (131) having a third dominant wavelength λd3 selected from the range of 470 nm to 500 nm; CRI1 - CRI2 ≥ 10; CRI1 ≥ 85; Tc2 - Tc1 ≥ 1000 K; Tc1 ≤ 3500 K; and Tc2 ≥ 3000 K; and the light generating system (1000) is configured to generate system light (1001) comprising one or more of the first device light (111), the second device light (121) and the third device light (131).

Description

TECHNICAL FIELD

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

[0003] JAN L. SOUMAN et al: "Spectral Tuning of White Light Allows for Strong Reduction in Melatonin Suppression without Changing Illumination Level or Color Temperature", JOURNAL OF BIOLOGICAL RHYTHMS., vol. 33, no. 4, 1 August 2018, pages 420-431, XP055647697, ISSN: 0748-7304, DOI: 10.1177 / 0748730418784041 discloses a lighting device having 11 different light sources, including two white light sources having CCTs of 2750 K and 4850 K, respectively, and blue, first green, second green, first red, second red, amber, violet and cyan LEDs. All these light sources are independently controllable.

[0004] WO2016 / 199101A2 discloses a lighting device having a plurality of independently controllable solid state light emitters, a sensor and a controller. The solid state light emitters include a blue LED with yellow / green phosphor (white LED), a short wavelength blue LED, a red LED, a green LED and a cyan LED.

[0005] WO2017 / 025613A1 discloses a lighting device comprising a first light source and a second light source, a control system configured to control the first light source and the second light source, wherein the first light source is configured to provide first light source light having a correlated color temperature of at maximum 3000 K and a color rendering index of at least 75, and wherein the second light source is configured to provide second light source light having a dominant wavelength selected from the range of 575 nm to 780 nm and having a color rendering index of at maximum 70.

[0006] WO2020 / 043649A1 discloses a light generating device configured to generate device light in a first control mode, wherein the light generating device comprises a first source having a first light and a second source having a second light different from the first light, wherein the second light comprises cyan light having a wavelength selected from the range of 470 nm to 520 nm, wherein the device light comprises the first light and the second light, and wherein in the first control mode the first light is white light and the device light is cyan light enriched white light. SUMMARY

[0007] 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 to lower CCTs (correlated color temperatures) 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 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 some extent.

[0008] In addition to the generally known cones and rods, the human eye has melanopsin containing photoreceptors which influence the circadian entrainment and melatonin secretion that are sensitive in a specific wavelength range. The relative spectral sensitivity of the classical receptors (rods and cones) and the melanopic receptors is provided in Figure 6 (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, https: / / www.sciencedirect.com / science / article / pii / S016622361300188X). http: / / www.sciencedirect.com / science / article / pii / S0166223613001975; In http: / / cie.co.at / index.php?i_ca_id=978 (with link to excel toolbox http: / / files.cie.co.at / 784_TN003_Toolbox.xlsReport on First International Workshop on Circadian and Neurophysiological Photometry, 2013". If 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 spectral power in the scotopic range is increased, exposure will result in stronger melatonin suppression. In general, when power in the scotopic range (and the ability to suppress melatonin at night) is increased, it can be said that the exposure has higher biological activity and higher alertness. 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 melanopic sensitivity function (m(λ)), divided by the product of the SPD(λ) and the photopic luminosity function (V(λ)), normalized by the area under the curves of m(λ) and V(λ), see equation 1 (see also figure 1).

[0009]

[0010] This can be simplified to

[0011]

[0012]

[0013] Hence, the above sum is in the visible range of 380-780 nm. By definition, an equi-energy light source MEF EE equals 1. In particular, an equi-energy light source has SPD(λ) = constant (e.g. 1) for all (visible) wavelengths.

[0014] 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).

[0015] 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 illuminance of a D65 source that is needed to produce the same iPRGC 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).

[0016] Instead of the MDEF value, also the MELR value (Melanopic Efficacy of 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.

[0017] 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.

[0018] As mentioned above, especially the MDEF is applied, which is further denoted herein as MDER. The MDER is defined as:

[0019]

[0020] 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.

[0021] 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 iPRGC stimulus is too low during the day (e.g. 500 lux, 4000 K, MDER ~ 0.6 in an office).

[0022] An increase of iPRGC stimulation can be related to different situations and / or settings. An increase of iPRGC stimulation can be done by increasing the illuminance and / or by increasing the MDER (higher CCT, rich in blue). Both options have limitations due to unwanted side effects, such as increasing glare and / or undesired high CCT (which seems not to be disliked by people). An alternative option for increasing the MDER can be done by increasing the intensity of the "cyan gap" in the spectrum. An adjustable (MDER) system would allow to adapt the scotopic stimulation to the time of day (e.g. high in the morning and low in the afternoon / evening). For example, the system can consist for example of two separate addressable channels: a warm white channel and a cyan rich channel (combined with a cool white LED). Then, a dual channel driver can be used to control the system, which uses a switch that defines the ratio between the two strings. In order to maintain a high CRI (Color Rendering Index, usually based on CRI Ra values) over a wide CCT range, it seems desirable to use high CRI cool white and warm white LEDs. Such an adjustable white system can maintain a very high CRI over the entire CCT range. However, such an adjustable white system with a very high CRI seems not to result in a strong MDER increase (or tunability). For a strong MDER increase, more cyan intensity is needed. In practice, the CRI can decrease with increasing CCT. For example, the CRI can be perceived to drop below 90 at ~3200K and even below 80 at ~4000K. This can not be preferred or even not compliant with office requirements.

[0023] It is therefore an aspect of the present invention to provide an alternative lighting system which preferably further at least partially obviates one or more of above-described drawbacks. It can be an aim of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide the public with a useful alternative.

[0024] Hence, in a first aspect, the present invention provides a tunable light generating system comprising one or more first light generating devices, one or more second light generating devices, and one or more third light generating devices. In embodiments, the one or more first light generating devices are configured to generate a white first device light having a first color rendering index CRI1 and a first correlated color temperature Tc1. Further, in embodiments, the one or more second light generating devices are configured to generate a white second device light having a second color rendering index CRI2 and a second correlated color temperature Tc2. Further, in embodiments, the one or more third light generating devices are configured to generate a third device light having a third dominant wavelength λd3 selected from the range of 470 nm to 500 nm. In particular, CRI1 - CRI2 > 10. Further, in specific embodiments, CRI1 > 85. Further, in particular, Tc2 - Tcl > 1000 K. Further, in specific embodiments, Tc1 < 3500 K and / or Tc2 > 3000 K. In particular, the tunable light generating system is configured to generate system light comprising one or more of the first device light, the second device light, and the third device light. Hence, in particular, in embodiments, the present invention provides a tunable light generating system comprising one or more first light generating devices, one or more second light generating devices, and one or more third light generating devices, wherein: (a) the one or more first light generating devices are configured to generate a white first device light having a first color rendering index CRI1 and a first correlated color temperature Tc1; (b) the one or more second light generating devices are configured to generate a white second device light having a second color rendering index CRI2 and a second correlated color temperature Tc2; (c) the one or more third light generating devices are configured to generate a third device light having a third dominant wavelength λd3 selected from the range of 470 nm to 500 nm; (d) CRI1 - CRI2 > 10; CRI1 > 85; Tc2 - Tcl > 1000 K; Tc1 < 3500 K; and Tc2 > 3000 K; and (e) the tunable light generating system is configured to generate system light comprising one or more of the first device light, the second device light, and the third device light.

[0025] With such a system, it is possible to adapt the black stimulus of the iPRGC to the time of day. Further, such a system allows to control the ratio of the light sources, in particular of the two strings with the respective light sources (see further below), by which the CCT and the MDER can be controlled. Further, surprisingly, with such a system it is possible to provide white system light with a high CRI, such as at least 80, over a relatively large range of CCTs.

[0026] The color temperature is based on the CIE 1960 diagram (u, v values, i.e. using the CIE 1931 2 degree color matching functions).

[0027] The color points can in particular herein be defined using the 10 degree color matching functions according to CIE S 014-1 / E:2006 (see Table 2).

[0028] As mentioned above, the application provides a tunable light generating system comprising one or more first light generating devices, one or more second light generating devices and one or more third light generating devices. In particular, the tunable light generating system comprises a plurality of first light generating devices and a plurality of second light generating devices and a plurality of third light generating devices.

[0029] 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.

[0030] The one or more first light generating devices are configured to generate a white first device light having a first color rendering index CRI1 and a first correlated color temperature TCI ("CCT1"). Further, the one or more second light generating devices are configured to generate a white second device light having a second color rendering index CRI2 and a second correlated color temperature TC2 ("CCT2").

[0031] The terms "first light generating device" and "second light generating device" especially refer to devices that are different, in particular in one or more spectral properties. Herein, the spectral distribution of the first device light and the second device light are different, and for example the color rendering index (CRI) can differ by at least 10 points. Hence, the spectral power distribution of the first light source light and the second light source light are different. Hence, in embodiments, the first color point and the second color point differ by at least 0.01 for u' and / or 0.01 for v' (such as by at least 0.02 for u' and / or 0.02 for v'). Even more in particular, in embodiments, the first color point and the second color point can differ by at least 0.03 for u' and / or 0.03 for v'.

[0032] As mentioned above, the first light generating device and the second light generating device are in particular configured to generate white light. However, the third light generating device is in particular configured to generate colored light, more in particular in embodiments cyan light. In particular, in embodiments, the one or more third light generating devices are configured to generate a third device light having a third dominant wavelength λd3 selected from the range of 470 nm to 500 nm.

[0033] As already mentioned, the first light generating device and the second light generating device are in particular configured to generate white light. However, they differ in terms of spectral characteristics of the respective device light. In particular, the CRI of the first device light is higher (in some embodiments substantially higher) than the CRI of the second device light. In embodiments, CRI1 - CRI2 > 10. Further, in particular, in embodiments, the CRI of the first device is relatively high, such as in particular CRI1 > 85. Further, the CCT of the first device light is smaller than the CCT of the second device light, in particular substantially smaller than the CCT of the second device light, in particular in embodiments. In embodiments, Tc2 - Tc1 > 1000 K. Further, in particular, in embodiments, Tci < 3500 K, such as Tci < 3400 K, as in particular Tci < 3200 K. In particular, in embodiments Tci < 3000 K. Alternatively or additionally, in embodiments Tc2 > 3000 K, such as in embodiments Tc2 > 3200 K, in particular in embodiments Tc2 > 3400 K, even more in particular in embodiments Tc2 > 3500 K. In particular embodiments, Tc2 > 4000 K. As mentioned above, Tc2 > Tci, more in particular Tc2 - Tci > 1000 K. Hence, the first device light can be indicated as warm white, whereas the second device light can be indicated as cool white.

[0034] As mentioned above, Tci < 3500 K and Tc2 > 3000 K. Even though the upper limit of Tci is higher than the lower limit of Tc2, the condition Tc2 - Tci > 1000 K applies. For example, Tci can be 2000 K and Tc2 can be 3000 K.

[0035] The tunable light generating system is configured to generate system light comprising one or more of the first device light, the second device light and the third device light. Whether the system light comprises all three contributions can depend on the way the devices are operated, such as with fixed spectral characteristics (substantially a single operating mode) or with controllable spectral characteristics (a plurality of operating modes), see also further below.

[0036] Further, the phrase "the tunable light generating system comprises one or more first light generating devices, one or more second light generating devices and one or more third light generating devices" does not exclude the presence of other light generating devices. Also the term "lighting system" or "system" can be applied herein instead of the term "tunable light generating system". Further, also the term "lighting device" or "device" can be applied herein instead of the term "light generating device". Herein, a light generating device especially comprises a solid state light source (see also further below).

[0037] In particular, the first device light is white light based on a color point using 10° color matching functions. Similarly, the second device light is white light based on a color point using 10° color matching functions.

[0038] Typically, the color point and the correlated color temperature are defined based on the 2° color matching functions, such as CIE 1931. As from the website https: / / www.konicaminolta.com / instruments / knowledge / color / part4 / 01.html obtained from, The color sensitivity of the eye changes as a function of the viewing angle (object size). CIE originally defined a standard observer in 1931 using a 2 field of view, hence the name 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, the 2° field of view would be a circle of 1.7 cm, while the 10° field of view at the same distance would be a circle of 8.8 cm. The color matching functions are the 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.

[0039] Hence, in this document CIE S 014-1 / E:2006 is used, see Tables 1 and 2, respectively.

[0040] 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 functions. For comparing the color points of the first device light and the second device light, in this document the color points using the 10° color matching functions are applied. Hence, for comparing these color points, both color points should be defined based on the 10° color matching functions. For comparing the color points of the first device light and the second device light, in this document typically the color points using the 2° color matching functions are applied. This also allows to provide a correlated color temperature.

[0041] Note that in a particular embodiment, the first device light and the second device light using the 2° color matching functions are white light. Similarly, in one or more operational modes, the system light is white light. Especially assuming the 2° color matching functions, the term “white light” in this document is known to the person skilled in the art. This document especially relates to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 K and 20000 K, especially 2700 K to 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.

[0042] Even if the second device light can have a CRI of 70 or lower, the color point is especially within 15 SDCM (2° color matching functions) from the BBL.

[0043] In particular, the first light generating device and the second light generating device each comprise one or more solid state light sources and one or more luminescent materials that convert at least a part of the respective solid state light source light of the respective solid state light source. In this way, the first device light and the second device light can be generated that comprise luminescent material light of the respective luminescent material and, optionally, also light source light of the respective solid state light source.

[0044] The first device light can have a first correlated color temperature Tci. In particular, in embodiments the first correlated color temperature Tci can be selected from the range of 1800 K - 3500 K, in particular at most about 3400 K, even more particularly at most about 2900 K, even more particularly at most about 2800 K, such as at most about 2700 K. More particularly, the first correlated color temperature Tci can be at least 1800 K, such as even more particularly at least about 1900 K. In yet another particular embodiment, the first correlated color temperature Tci can be selected from the range of at least 2000 K, such as from the range of 2000 K - 3400 K, such as from the range of 2000 K - 3200 K, like in particular embodiments 2000 K - 2900 K. Hence, the first light generating device can be indicated as a warm white light generating device.

[0045] Further, the second device light can have a second correlated color temperature Tc2. In particular, in embodiments the second correlated color temperature Tc2 can 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 Tc2 can 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 Tc2 can be selected from the range of at least 4500 K, such as at least 5000 K, such as from the range of 5000 - 6500 K. Hence, the second light generating device can be indicated as a cool white light generating device. Hence, in embodiments Tc2 > 3400 K.

[0046] In particular, in embodiments Tc2 - Tci > 2500 K, such as Tc2 - Tci > 3000 K. In such embodiments, a wide tunable range can be obtained.

[0047] The first device light can have a CRI of at least about 85, even more particularly at least about 90. Hence, in embodiments CRIi > 90. The second device light can have a CRI of at most about 75, such as more particularly at most about 70. In embodiments, the CRI of the second device light can be selected from the range of 55 - 75. Further, the difference between the CRIs can be at least 10, such as even more particularly at least 15. Hence, in embodiments CRIi - CRI2 > 15.

[0048] As indicated above, the spectral power distribution of the first light source light and the second light source light can be different.

[0049] In particular, 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 an LED. The third dominant wavelength λd3 is especially selected from the range of 470 nm to 500 nm. Hence, the third light source is especially a cyan light source, such as a cyan LED. More in particular, the third dominant wavelength λd3 can be selected from the range of 470 nm to 490 nm. Best results are obtained using a third dominant wavelength λd3 selected from the range of 474 nm to 484 nm. Even more in particular, the third dominant wavelength λd3 can be selected from the range of 478 nm to 484 nm, such as about 480 nm. Alternatively, the third light generating device can comprise a blue and / or UV solid state light source, and a luminescent material configured to convert the blue and / or UV light of the solid state light source into cyan light (cyan third device light). 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 "luminescent material" can also refer to a plurality of different luminescent materials.

[0050] Hence, in embodiments, the tunable light generating system can comprise one or more first light generating devices and 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). Hence, in such embodiments, the system light can essentially consist of the first device light and the second device light and the third device light. However, in specific embodiments, the tunable 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 one or more first light generating devices and the one or more second light generating devices and the one or more third light generating devices. Hence, in such embodiments, the system light can essentially consist of one or more of the first device light and the second device light and the third device light.

[0051] The term "control" and similar terms refer, inter alia, to at least determining a behavior of an element or supervising a running of an element. Hence, "control" and similar terms here can refer, for example, to exerting a behavior on an element (determining a behavior or supervising a running of an element), such as measuring, displaying, actuating, opening, displacing, changing a temperature, etc. In addition thereto, the term "control" and similar terms can additionally include monitoring. Hence, the term "control" and similar terms can include exerting a behavior on an element as well as exerting 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, 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.

[0052] 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 smartphone or I-phone, a tablet, etc.). Hence, the device does not necessarily have to be coupled to the lighting system, but can be (temporarily) functionally coupled to the lighting system.

[0053] 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 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, which accesses the lighting system based on knowledge of the (unique) code (which is input via a user interface with an optical sensor, like a QR code reader). 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.

[0054] 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.

[0055] However, in embodiments, a control system can be available which 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 (like performing a mode according to a sensor signal or a (time) scheme) are possible as well. In embodiments, the operating mode can also refer to a system, apparatus or device which is only capable of operating in a single operating mode (i.e. "on" without further tunability).

[0056] 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.

[0057] 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.

[0058] Hence, in embodiments, the tunable 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 further type of light generating devices (which can contribute to the system light). Hence, 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 tunable 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. Hence, 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.

[0059] 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 a particular embodiment, 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 in embodiments to a so-called chip-on-board (COB) light source. The term "COB" especially refers to an LED chip in the form of a semiconductor chip that is neither encapsulated 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 (essentially identical (or different)) light sources such as 2 to 2000 solid state light sources. In embodiments, the light source can comprise one or more micro-optical elements (microlens array) downstream of a single solid state light source such as an LED or of a plurality of solid state light sources (i.e. shared by a plurality of LEDs). 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).

[0060] The phrase "different light sources" or "a plurality of different light sources" and similar phrases can refer in embodiments to a plurality of solid state light sources selected from at least two different bins. Likewise, the phrase "same light sources" or "a plurality of same light sources" and similar phrases can refer in embodiments to a plurality of solid state light sources selected from the same bin.

[0061] In a particular embodiment, the one or more luminescent materials can comprise quantum dots. Alternatively or additionally, in embodiments the one or more luminescent materials can comprise a cerium containing garnet type luminescent material. Alternatively or additionally, in embodiments the one or more luminescent materials can comprise a divalent europium based nitride material. Alternatively or additionally, in embodiments the one or more luminescent materials can comprise a cerium containing garnet type luminescent material and a divalent europium based nitride material. In further embodiments, the one or more luminescent materials can comprise a Mn 4+ based narrow-band red emitting phosphor.

[0062] When luminescent material is applied herein, the luminescent material is especially configured downstream of a light source, such as a white light emitting solid state light source in the above described 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.

[0063] For green, yellow, orange and / or red emitting luminescent materials (e.g. inorganic luminescent materials with an activator or active substance can be applied). The relevant active substance can be for example Eu 2+ or Ce 3+ . Other active substances can be quantum dots. Yet other active substances can be organic luminescent dyes.

[0064] 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 include 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; however, in particular doped 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 in particular be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and / or Tb are in particular present only in an amount up to about 20% of A. In a particular embodiment, the garnet luminescent material comprises (Y 1-x Lu x )3B5O 12 :Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1.

[0065] The term ":Ce" indicates that part of the metal ions in the luminescent material (i.e. part of the "A" ions in the garnet) 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 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, a completely correct formula can be (Y 0.1 Lu 0.89 Ce 0.01 )3Al5O 12 .

[0066] As is known to the person skilled in the art, Ce in the garnet is essentially or only in the trivalent state.

[0067] 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 are replaced by Eu (in these embodiments by Eu 2+ replaced). For example, assuming 2% Eu in CaAlSiN3:Eu, a 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.

[0068] The material (Ba,Sr,Ca)S:Eu can also be denoted as MS: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).

[0069] Further, 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 taking into account 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 Sr0.5 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).

[0070] 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 the compound. Here, Eu is incorporated and replaces at least part of M (i.e. one or more of Ba, Sr and Ca).

[0071] As known to the person skilled in the art, Eu in the above luminescent materials is essentially or only in the divalent state.

[0072] Garnet-type luminescent materials can in particular be used as second and / or third luminescent material.

[0073] The term "luminescent material" herein relates in particular to inorganic luminescent materials, which are sometimes also denoted as phosphors. These terms are known to the person skilled in the art. The term "luminescent material" refers in particular to a material which can convert one or more of a first radiation, in particular UV radiation and blue radiation, into a second radiation. Typically, the first radiation and the second radiation have a different spectral power distribution. Instead of the term "luminescent material", the term "luminescence converter" or "converter" can also 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 particular embodiments, the second radiation has a spectral power distribution with intensity at a smaller wavelength than the first radiation, which is the case in so-called up-conversion. In embodiments, "luminescent material" can in particular refer to a material which can convert radiation into e.g. visible light and / or infrared light. For example, in embodiments, the luminescent material is capable of converting one or more of UV radiation and blue radiation into visible light. In particular embodiments, the luminescent material can also convert radiation into infrared radiation (IR). Thus, upon excitation with radiation, the luminescent material emits radiation. Typically, the luminescent 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 particular embodiments, the luminescent material can comprise a down-converter luminescent material, i.e. a larger wavelength radiation is converted into a radiation having a smaller wavelength (λ ex >λ em). In embodiments, the term "luminescence" can refer to phosphorescence. In embodiments, the term "luminescence" can also refer to fluorescence. Instead of the term "luminescence", the term "emission" can also be applied. Thus, the terms "first radiation" and "second radiation" can refer to excitation radiation and emission (radiation), respectively. Likewise, the term "luminescent material" can in embodiments relate to phosphorescence and / or fluorescence. The term "luminescent material" can also refer to a plurality of different luminescent materials.

[0074] As mentioned above, in particular embodiments, the tunable light generating system can optionally further comprise a control system configured to control the first light generating device and 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 (see also further below).

[0075] With the present application, the system light can be provided with a relatively high MDER. Moreover, 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).

[0076] With respect to the MDER value, in the operational mode of the light generating system, the system light can have a MDER value selected from the range of at least 0.45, even more particularly at least 0.65, wherein the MDER is defined as:

[0077]

[0078] wherein SPD(λ) is the spectral power distribution of the system light, m(λ) is the black- vision sensitivity function, V(λ) is the photopic luminosity function.

[0079] Moreover, in particular embodiments, in the operational mode of the light generating system, the system light can have a CRI of at least 80. Furthermore, in particular embodiments, in the operational mode of the light generating system, the system light can have a R9 value of at least 50. Thus, in particular embodiments, in the operational mode of the light generating system, the system light can have a MDER of at least 0.45, a CRI of at least 80, such as at least 85, and a R9 of at least 50. In particular, the system light can have a MDER of at least 0.65.

[0080] 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.

[0081] As mentioned above, in embodiments, the tunable 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 possible as well.

[0082] It appears particularly useful in terms of tunability of CRI and CCT when there is a certain distance between the (shallow) blue emission band and the (shallow) green emission band. This distance, measured as the distance between the respective half-widths, can in particular be selected from the range of 30 nm to 60 nm, such as the range of 35 nm to 55 nm. When the distance is smaller or larger, the tunability over CCT can decrease while maintaining a high CRI. In other words, tunability over a (large) CCT range can still be present, but only at the expense of a lower CRI, such as below 90, or even below 85, which can be less desirable. Hence, in embodiments, the white second device light comprises (i) a first emission band having a peak wavelength below 490 nm and having a first full-width-half-maximum defined by a first lower wavelength and a first upper wavelength (lbiR), and (ii) a second emission band having a maximum intensity at a wavelength selected from the range of 500 nm to 650 nm and having a second full-width-half-maximum defined by a second lower wavelength l b2B and a second upper wavelength, wherein 30 nm < l2B - lbiR < 60 nm. Even more particularly 35 nm < l b2B - lbiR < 55 nm, such as 35 nm < l b2B - lbiR < 50 nm.

[0083] The first, second and third light generating devices are configured in a first LED string. The first light generating device is configured in a first LED string, the second and third light generating devices are configured in a second LED string. The tunable light generating system is configured to control the ratio of the first LED string and the second LED string. This allows controlling the CCT. Further, this allows a high MDER at high CCT and a relatively low MDER at low CCT. Further, as mentioned above, this allows a high CRI over a range of CCTs. Thus, the CRI is kept at a high level while allowing a relatively high number of cyan LEDs, i.e. a relatively high MDER value.

[0084] The tunable light generating system can comprise (i) a first LED string comprising one or more first light generating devices, and (ii) a second LED string comprising one or more second light generating devices and one or more third light generating devices.

[0085] In particular, in embodiments, the second LED string comprises n2 second light generating devices and n3 third light generating devices, wherein n2 > 1 and n3 > 1, and wherein n3 / n2 > 0.25. For example, nl = 12, n2 is at least 2, n3 is at least 3, and n2 + n3 = nl. However, other numbers are possible as well.

[0086] Whether or not strings are used, in particular in embodiments, the tunable light generating system can comprise nl first light generating devices, n2 second light generating devices and n3 third light generating devices, wherein nl > 6, n2 > 3 and n3 > 3. Further, in particular n3 / n2 > 0.25. Also, typically n3 / n2 < 2.

[0087] The distance between the third light generating devices can not be too large in view of color uniformity. For example, in embodiments, the second light generating devices and the third light generating devices have a (first) shortest distance (dl) from each other, wherein the shortest distance dl < 3.5 cm. Further, in embodiments, the third light generating devices have a (third) shortest distance (d3) from each other, wherein the shortest distance d3 < 3.5 cm. The second light generating devices can have a (second) shortest distance, which can also be d2 < 3.5 cm in embodiments. The expression “shortest distance” is typically the distance between two light generating devices measured along the shortest path between them, i.e. along the path between their two adjacent side surfaces. Other types of light generating devices can be between those two adjacent light generating devices.

[0088] In particular, the system light can be white light in one or more operational modes. For example, in one or more of these one or more operational modes, the MDER can be at least 0.65. Further, the CRI of the (white) system light can be at least 80, such as at least 85, like at least about 87 or higher in embodiments. For example, in embodiments, the CRI can be maintained at least 80 in a range of at least about 1000 K. In particular embodiments, the system can be configured to produce white system light in one or more operational modes comprising the first device light, the second device light, and the third device light, wherein the system light has a CRI of at least 80 and / or a MDER of at least 65. In embodiments, the CRI can be at least 85 at least above 500 K, such as at least above 1000 K.

[0089] As mentioned above, the system light (in these one or more operational modes) can have a color point within about 15 SDCM (more particularly within about 10 SDCM, such as particularly within about 5 SDCM) from the BBL. Here, particularly the 2° color matching function can apply (see also above). Further, the system light can particularly have an R9 value of at least about 50, such as at least about 70, even more particularly at least about 80, still even more particularly at least about 85. Particularly, the R9 can be at least 80 at least above 1000 K. Even more particularly, the R9 can be at least 50 above 1000 K, even more particularly at least about 80 above 1000 K, such as at least about 85 above 1000 K (even more particularly above 1500 K) in further particular embodiments. Thus, in particular embodiments, the system light can have an R9 of at least 85. Herein, the phrase “above xxx K” particularly indicates a tunable range of CCT.

[0090] Thus, in embodiments, the control system can be configured to control a spectral power distribution of a system light of a tunable light generating system, such as a tunable light generating system, wherein the system comprises (i) a first LED string comprising one or more first light generating devices, and (ii) a second LED string comprising one or more second light generating devices and one or more third light generating devices,

[0091] Note that in particular embodiments, the term “first string” can also refer to a plurality of first strings arranged in electrical parallel. Note that in particular embodiments, the term “second string” can also refer to a plurality of second strings arranged in electrical parallel.

[0092] In yet another aspect, the application provides a lamp or lighting device comprising a tunable light generating system as defined herein. The lighting device can further comprise a housing, optical elements, louvres, etc. The lamp or lighting device can further comprise a housing encapsulating the first light generating device, the second light generating device and optionally the third light generating device. The lamp or lighting device can comprise a light window or housing opening in the housing through which system light can escape from the housing.

[0093] The tunable 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 theatre lighting system, a fiber application system, a projection system, a self-illuminating 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.

[0094] 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.

[0095] 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

[0096] 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:

[0097] Figures 1A to 1C Some embodiments are schematically depicted.

[0098] Figures 2A to 2B Some embodiments are schematically depicted.

[0099] Figures 3A to 3C Spectral power distributions of system light are shown, as well as some further aspects;

[0100] Figure 4 Relative photopic (i.e. m( )) and V( ) human eye sensitivity functions are shown; and

[0101] Figure 5 2° and 10° color matching functions are provided (such as derived from CIE S 014-1 / E:2006). The schematics are not necessarily drawn to scale. DETAILED DESCRIPTION

[0102] As mentioned above, the stimulation of iPRGC can be increased by increasing the illuminance and / or by increasing the MDER (higher CCT, rich in blue). Both options have limitations due to unwanted side effects of increasing glare, people do not like very high CCT. Another option is to increase the MDER by filling the cyan gap in the spectrum. An adjustable (MDER) system would allow to adapt the scotopic stimulation to the time of day (e.g. high in the morning and low in the afternoon / early evening). A relatively simple system can consist of two separate addressable strings: a warm white channel and a cyan rich channel (which is combined with cool white LEDs). Then, a dual channel driver can be used to control the system, which uses switches that define the ratio between the two strings.

[0103] For driver and color uniformity reasons, the string length can for example be 12 (LEDs or chips), and in embodiments the number of cyan LEDs per string can be even, such as at least 4, like at least 6. Since a CRI > 90 over a wide range is particularly desirable, the warm white LEDs (2700K or 3000K) should have a CRI of at least 90 (at low CCT, the light can be generated substantially only by the warm white LEDs).

[0104] Multiple simulations have been performed:

[0105] 1) Simulate CRI as a function of CCT using warm white LEDs with CRI 90-100 and cool white LEDs with CRI 90-100 or CRI 80 LEDs. Determine string length equal to 12 LEDs. The cool white string contains for example 0 cyan LEDs, 2 cyan LEDs, 4 cyan LEDs or 6 cyan LEDs;

[0106] 2) For the same string sets as shown in 1, determine scotopic-DER as a function of CCT;

[0107] 3) For a system with 0, 2, 4, and 6 cyan LEDs in the cool white string, and string length = 12, the CRI is simulated as a function of CCT. In addition, it varies between cool white LEDs with a CCT of 6500 but with a CRI of 70 or 80;

[0108] 4) For the same string sets as shown in 3, the black- view-DER is determined as a function of CCT; and

[0109] 5) For the number of strings shown above, the R9 is determined as a function of CCT.

[0110] To maintain a high CRI over a wide CCT range, it seems necessary to use cool white LEDs with a high CRI (e.g., a CRI of about 100 and a CCT of e.g., 6500 K). It appears that tunable white systems maintain a very high CRI over the entire CCT range. However, tunable white does not result in a strong MDER increase. For example, for a system with 4 or 6 cyan LEDs per string, the CRI appears to decrease rapidly with increasing CCT. For example, the CRI drops below 90 at ~3200 K and even below 80 at ~4000 K. This is clearly not preferred, or even possibly not compliant with office requirements.

[0111] It further appears that combining LEDs with a CRI of at least 90 and a CCT of 3000 K with LEDs with a CRI of 80 and a CCT of 6500 K, the CRI decreases with CCT. In addition, it appears that with a cyan LED count in the second string of about 50% of the LEDs, the CRI drops below 90 at ~3000 K and below 80 at ~4000 K. Only with a very low cyan count, the CRI remains above 90 over a wide CCT range (~6000 K). However, a lower cyan LED count is not desirable for e.g., linear systems, since the spacing between the cyan LEDs can be too large, possibly resulting in an undesirable color variation over the length of the board. Also, the MDER increase of such a system can be limited (high intensity in the cyan region results in a high black-view-DER but reduces the CRI; thus, there is always a trade-off between MDER and light quality).

[0112] Surprisingly, a solution was found in embodiment 2 - the channel tunable high black system - that maintains CRI at a high level for systems with a high count of blue LEDs. In the embodiment, the system can use high CRI warm white LEDs in one string, while in a second string a combination of blue and cool white LEDs is used. In particular, the high CRI warm white LEDs (CRI of at least 90) are combined with cool white LEDs that have a much lower CRI (should be such as at maximum 80, in particular at maximum about 75, such as about 70).

[0113] Thus, in particular, a tunable white light system is provided with high MDER at high CCT and low / normal MDER at low CCT while maintaining good color quality (i.e. white appearance, CRI of at least 80 and R9 of at least 50) by combining direct blue LEDs with a dominant wavelength (DWL) of e.g. ~482 nm with CRI 70 cool white LEDs in one string and warm white LEDs with a CRI of at least 90 in another string. By properly choosing the blue DWL, the resulting color point of the light source can be tuned below the BBL (2 degree matching function), which looks desirable.

[0114] In the embodiment, the tunable system can have two separate addressable channels: warm white (e.g. 12 LEDs) and cool white string consisting of (12-x) cool white LEDs and x blue LEDs. Here, each LED contains 1 chip or die; if each LED of one or more LED types has multiple chips, the number of LEDs per channel should be divided by this factor. By e.g. varying the duty cycle between the two channels, CCT-MDER tuning can be obtained.

[0115] In particular, it appears that using LEDs with a CCT of about 6500 and a CRI of only 70 is superior to using LEDs with about the same CCT but a CRI of 80, in particular because the number of blue LEDs in the cool white string can be larger. Thus, a more uniform configuration can be provided.

[0116] Further, it appears that with a number of blue LEDs equal to e.g. 4, a system is obtained that maintains a CRI of at least 90 over a wide CCT range (e.g. 3000K-6000K). However, a tunable white system using CRI 90+ LEDs (without blue LEDs) can do so as well, but the MDER will be much lower.

[0117] Furthermore, it appears that with a number of cyan LEDs equal to 6, for a system using CRI 80 and CCT 6500K LEDs, the CRI can drop below approximately 80 at ~4700K. Increasing the CRI of the cool white LEDs can even lead to a more limited CCT range with a CRI of at least 80. However, using CRI 70 / CCT 6500K LEDs significantly improves the tuning range. Furthermore, using CRI 70 / CCT 6500 LEDs (pumped using shorter wavelength blue LEDs) can lead to a system with a tuning range of approximately 3000K-6500K, while keeping the CRI >80.

[0118] If R9 is larger than 50, an extra WELL (standard) point can be obtained. At least 1 / 3 of all LEDs in the second string are cyan LEDs / all systems with a string of cyan LEDs appear to meet this requirement.

[0119] Of course, generating light in spectral regions with lower eye sensitivity, like the cyan region, reduces the efficiency. The more cyan LEDs in the cool white string, the lower the efficiency at higher CCTs. Also here, using CRI 70 / CCT 6500K LEDs instead of CRI 80 / CCT 6500K LEDs is beneficial, as it leads to higher efficiency. So, in conclusion, CRI 70 / CCT 6500K LEDs in combination with the use of cyan LEDs gives a higher CRI and higher efficiency compared to CRI 80 / CCT 6500K LEDs with cyan LEDs, and a higher MDER compared to no cyan LEDs, and it can provide a system light with a desired R9.

[0120] Some embodiments are further described below in connection with the accompanying drawings.

[0121] Figure 1AAn embodiment of a tunable light generating system 1000 is schematically illustrated, which comprises one or more first light generating devices 110, one or more second light generating devices 120, and one or more third light generating devices 130. The one or more first light generating devices 110 are configured to generate white first device light 111 having a first color rendering index CRI1 and a first correlated color temperature Tc1. The one or more second light generating devices 120 are configured to generate white second device light 121 having a second color rendering index CRI2 and a second correlated color temperature Tc2. The one or more third light generating devices 130 are configured to generate third device light 131 having a third dominant wavelength λd3 selected from a range of 470 nm to 500 nm. In particular, one or more (especially all) of the following apply: CRI1 - CRI2≥ 10; CRI1≥ 85; Tc2 - Tc1≥ 1000 K; Tc1≤ 3500 K; and Tc2≥ 3000 K. In embodiments, Tc2≥ 3400 K. Further, in particular, the third dominant wavelength λd3 is selected from a range of 470 nm - 490 nm, such as in embodiments selected from a range of about 478 nm - 484 nm. In further specific embodiments, Tc2 - Tc1≥ 2500 K; CRI1 - CRI2≥ 15; and CRI1≥ 90. In particular, the tunable light generating system 1000 is configured to generate system light 1001 comprising one or more of the first device light 111, the second device light 121, and the third device light 131.

[0122] Reference sign 353 refers to a sensor, especially an optical sensor (such as a daylight sensor or a motion sensor). Reference sign 300 refers to a control system. Reference sign 351 refers to a user interface (such as a smartphone). Hence, the tunable light generating system 1000 can further comprise a control system 300 configured to control one or more of the one or more first light generating devices 110, one or more of the one or more second light generating devices 120, and one or more of the one or more third light generating devices 130. Further, the tunable 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 a sensor 353. In particular, the control system 300 is configured to control the spectral power distribution of the system light 1001 in response to a signal of the input device 350. Hence, the control system 300 is configured to control the spectral power distribution of the system light 1001.

[0123] Reference is made to Figure 1BThe tunable light generating system 1000 can comprise a first LED string 2100 comprising one or more first light generating devices 110 and a second LED string 2200 comprising one or more second light generating devices 120 and one or more third light generating devices 130. In embodiments, the second LED string comprises n2 second light generating devices 120 and n3 third light generating devices 130, with n2 > 1 and n3 > 1, and with n3 / n2 > 0.25.

[0124] Furthermore, in embodiments, the tunable light generating system 1000 can (typically) comprise n1 first light generating devices 110, n2 second light generating devices 120 and n3 third light generating devices 130, with in particular n1 > 6, n2 > 3 and n3 > 3. In particular, in embodiments n1 = n2 + n3.

[0125] As Figure 1C As schematically depicted in Fig. 1 1 1, the second light generating devices 120 and the third light generating devices 130 can have a minimum distance d1 from each other. For example, the minimum distance d1 < 3.5 cm. As schematically depicted in Fig. 1 1 1, the second light generating devices 120 can have a minimum distance d2 from each other. For example, these minimum distances d2 < 3.5 cm. As schematically depicted in Fig. 1 1 1, the third light generating devices 130 can have a minimum distance d3 from each other. For example, these minimum distances d3 < 3.5 cm. Figure 1C Figure 1C

[0126] In embodiments, in the 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:

[0127]

[0128] wherein SPD( ) is the spectral power distribution of the system light 1001, m( ) is the photopic luminosity function and V( ) is the photometric luminance function.

[0129] Hence, in embodiments, the control system 300 can be configured to control the spectral power distribution of the system light 1001 in the operational mode while maintaining a predetermined MDER value. In particular, in embodiments, the control system 300 can be configured to control the MDER value in the operational mode in dependence on a signal of the input device 350.

[0130] Figure 2A ​​An embodiment of a lamp 1 (Embodiment I) or an illumination device 2 (Embodiment II) including a tunable light generating system 1000 is schematically depicted. In Embodiment II, reference numeral L denotes a light-shielding grid. However, other embodiments are of course possible.

[0131] Figure 2B An embodiment of a lamp 1 or lighting device 2 including a tunable light generating system 1000 is also schematically depicted.

[0132] Figure 3A Some spectral distributions of the system light (1000) are shown. Continuous lines represent different white spectra with CRI 90 and CCT 2700K or 3000K, or with CRI 70 or CRI 80 and CCT 6500K. Dashed lines show combinations of warm and cool white with cyan bands that have different relative contributions, resulting in CCTs of 3500K, 4000K, and 5000K. Therefore, an example of a white system light with a CCT in the range of 3500-5000K is shown here. The following optical properties were obtained:

[0133] CCT 3500K 4000K 5000K MDER 0，683 0，838 1，015 CRI 88，2 85，5 81，1

[0134] In an embodiment, in the operating mode of the tunable light generation system 1000, the (white) second device light 121 includes a blue first emission band having a peak wavelength below 490 nm and a first full width at half maximum (FWHM) defined by a first smaller wavelength λ1bB and a first larger wavelength λb1R, and a green / yellow second emission band having maximum intensity at a wavelength selected from the range of 500 nm to 650 nm and a second full width at half maximum (FWHM) defined by a second smaller wavelength λb2B and a second larger wavelength λ2bR, wherein 35 nm ≤ λb2B - λb1R ≤ 55 nm. Figure 3B and Figure 3C This has been illustrated in more detail. The cyan band has been removed for clarity.

[0135] Figure 4 The sensitivity functions of the human eye for relative blackout (m) (i.e., m(λ)) and photopic (V(λ)) are shown. The maximum sensitivity of blackout function is 490 nm, and the full width at half maximum (FWHM) is 447 nm and 531 nm, respectively. See the appendix for the sensitivity functions of blackout and photopic eyes as well.

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[0137]

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[0139]

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[0142]

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[0146] Figure 5 2° and 10° color matching functions are provided (such as derived from CIE S 014-1 / E:2006).

[0147] The term "plurality" means two or more.

[0148] The terms "substantially" and "essentially" and similar terms in the present text will be understood by the skilled person. The terms "substantially" and "essentially" can also include embodiments with "entirely", "completely", "all", etc. 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, in particular 99% or more, even more in particular 99.5% or more, including 100%.

[0149] The term "comprising" also includes embodiments where the term "comprising" is interpreted as "consisting of".

[0150] The term "and / or" relates in particular to one or more of the items preceding and following the "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".

[0151] 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 operating in other sequences than described or illustrated herein.

[0152] These devices, apparatuses or systems can be described herein, inter alia, during operation. As will be clear to the skilled person, the application is not limited to methods of operation, or devices, apparatuses or systems in operation.

[0153] It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that one skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0154] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0155] The use of the verb "comprise" and its conjugations does not exclude the presence of elements other than those stated in the claims. In the entire description and claims, the word "comprising" and its conjugations should not be interpreted as being restricted to the meaning of "including only that stated in the claims"; that is to say, in the sense of "including, but not limited to, that stated in the claims".

[0156] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0157] The application can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that several elements are recited in mutually different dependent claims does not indicate that a combination of these elements cannot be used to advantage.

[0158] The application also provides a control system, which can control an apparatus, device or system, or which can carry out a method or process as described herein. Furthermore, the application also provides a computer program product, which, when run on a computer functionally coupled to or comprised by an apparatus, device or system, controls one or more controllable elements of such apparatus, device or system.

[0159] The application is also applicable to an apparatus, device, or system comprising one or more characterising features described in the description and / or shown in the attached drawings. The application is further directed to a method or process comprising one or more characterising features described in the description and / or shown in the attached drawings.

[0160] The various aspects discussed in this patent can be combined to facilitate providing additional advantages. Furthermore, those skilled in the art will recognize that the embodiments can be combined and that more than two embodiments can be combined. In addition, some features can form the basis of one or more divisional applications.

Claims

1. A tunable light generation system (1000), comprising one or more first light generating devices (110), one or more second light generating devices (120), and one or more third light generating devices (130), wherein: - The one or more first light generating devices (110) are configured to generate white first device light (111), the white first device light having a first color rendering index CRI1 and a first correlated color temperature Tc1; - The one or more second light generating devices (120) are configured to generate white second device light (121) having a second color rendering index CRI2 and a second correlated color temperature Tc2; - The one or more third light generating devices (130) are configured to generate third device light (131) having a third dominant wavelength λd3 selected from the range of 470 nm to 500 nm. -CRI1 - CRI2 ≥ 10; CRI1 ≥ 85; Tc2 - Tc1 ≥ 1000K; Tc1 ≤ 3500K; and Tc2 ≥ 3000K; and - The tunable light generation system (1000) is configured to generate system light (1001), the system light including one or more of the first device light (111), the second device light (121), and the third device light (131). The tunable light generation system (1000) further includes: (i) a first LED string (2100) comprising the one or more first light generating devices (110), and (ii) a second LED string (2200) comprising the one or more second light generating devices (120) and one or more third light generating devices; and The tunable light generating system (1000) is also configured to control the ratio of the first LED string (2100) to the second LED string (2200).

2. The tunable light generation system (1000) according to claim 1, wherein Tc1 ≤ 3400 K and wherein Tc2 ≥ 3400 K.

3. The tunable light generation system (1000) according to any one of the preceding claims, wherein the third dominant wavelength λd3 is selected from the range of 470 nm to 490 nm.

4. The tunable light generation system (1000) according to any one of claims 1 and 2, wherein the third dominant wavelength λd3 is selected from the range of 478 nm to 484 nm.

5. The tunable light generation system (1000) according to any one of claims 1 and 2, wherein Tc2-Tc1 ≥ 2500K; CRI1-CRI2 ≥ 15; and CRI1 ≥ 90.

6. The tunable light generation system (1000) according to any one of claims 1 and 2, wherein in the operating mode of the light generation 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 0.45 to 1.3, wherein MDER is defined as: Where SPD(λ) is the spectral power distribution of the system light (1001), m(λ) is the black-vision sensitivity function, and V(λ) is the photopic brightness function.

7. The tunable light generation system (1000) according to any one of claims 1 and 2, wherein the white second device light (121) comprises (i) a first emission band having a peak wavelength below 490 nm and a first full width at half maximum (FWHM) defined by a first smaller wavelength and a first larger wavelength λb1R, and (ii) a second emission band having a maximum intensity at a wavelength selected from the range of 500 nm to 650 nm and a second full width at half maximum (FWHM) defined by a second smaller wavelength λb2B and a second larger wavelength, wherein 35 nm ≤ λb2B - λb1R ≤ 55 nm.

8. The tunable light generation system (1000) according to any one of claims 1 and 2, wherein the system light (1001) has a color point within approximately 15 SDCM of the blackbody trajectory BBL.

9. The light generating system (1000) according to claim 8, wherein the second LED string comprises n2 second light generating devices (120) and n3 third light generating devices (130), wherein n2≥1 and n3≥1, and wherein n3 / n2≥0.

25.

10. The tunable light generation system (1000) according to any one of claims 1, 2 and 9, comprising n1 first light generating devices (110), n2 second light generating devices (120) and n3 third light generating devices (130), wherein n1≥6, n2≥3 and n3≥3, wherein the third light generating devices (130) have a minimum distance (d3) between them, wherein the minimum distance (d3) ≤3.5cm.

11. The tunable light generation system (1000) according to any one of claims 1, 2 and 9, further comprising a control system (300) configured to control one or more of the one or more first light generation devices (110), one or more of the one or more second light generation devices (120), and one or more of the one or more third light generation devices (130).

12. The tunable light generation system (1000) according to claim 11 further includes an input device (350) selected from the group consisting of a user interface (351), a timing device, and a sensor (352), wherein the control system (300) according to any one of claims 8 to 9 is configured to control the spectral power distribution of the system light (1001) in response to a signal from the input device.

13. The tunable light generation system (1000) according to any one of claims 1, 2, 9, and 12, wherein the control system (300) is configured to control the spectral power distribution of the system light (1001) in an operating mode while maintaining a predefined MDER value, wherein the MDER value is defined as: Where SPD(λ) is the spectral power distribution of the system light (1001), m(λ) is the black-vision sensitivity function, and V(λ) is the photopic brightness function.

14. The tunable light generation system (1000) according to any one of claims 1, 2, 9 and 12, configured to generate white system light (1001) in one or more operating modes, the white system light (1001) comprising the first device light (111), the second device light (121) and the third device light (131), wherein the system light (1001) has a CRI of at least 80 and an R9 of at least 85.

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

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