2023PF80227 1 pc-LED lighting device comprising a plurality of phosphors with differential phosphor pumping FIELD OF THE INVENTION The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system. BACKGROUND OF THE INVENTION Luminescent bodies comprising phosphors are known in the art. For instance, CN112331755A describes a LED unit and application thereof. The LED unit comprises an LED chip, first fluorescent powder and second fluorescent powder, the peak wavelength of the LED chip ranges from 455 nm to 460 nm, the excitation wavelength of the first fluorescent powder ranges from 520 nm to 545 nm, the excitation wavelength of the second fluorescent powder ranges from 620 nm to 650 nm, and the first fluorescent powder and the second fluorescent powder are located in the light emitting direction of the LED chip. US2020/303355A1 discloses a LED-filament that includes a partially light- transmissive substrate; blue LED chips mounted on a front face of the substrate; first broad- band green to red photoluminescence materials and a first narrow-band manganese-activated fluoride red photoluminescence material covering the blue LED chips and the front face of the substrate; and second broad-band green to red photoluminescence materials covering the back face of the substrate. The LED-filament can further include a second narrow-band manganese-activated fluoride red photoluminescence material on the back face of the substrate in an amount that is less than 5 wt. % of a total red photoluminescence material content on the back face of the substrate. WO2023/137473A1 discloses a lighting device comprising: a first LED that generates light with a peak emission wavelength from 620 nm to 640 nm (i.e. orange to red); a second LED that generates light with a peak emission wavelength from 500 nm to 565 nm (i.e. green); a third LED that generates light with a dominant wavelength from 430 nm to 480 nm (violet to blue); and a fourth LED that generates white light with a CCT from 1800K to 5000K; wherein the first LED comprises a phosphor-converted LED that comprises a first LED chip that generates light with a dominant wavelength from 400 nm to 480 nm, and a
2023PF80227 2 narrowband red phosphor with a FWHM less than 55 nm; and wherein light generated by the device comprises a combination of light generated by the first, second, third, and fourth LEDs and wherein a CCT of light generated by the device is tunable from 1800K to 8000K by independently controlling power to the first, second, third, and fourth LEDs. SUMMARY OF THE INVENTION Prior art systems comprising transition-metal-ions Mn4+ activated fluoride based phosphors (or luminescent materials) have shown high luminescence efficiency. However, this class of luminescent material may suffer from droop. Droop in phosphors is a phenomenon describing their tendency to lose efficiency as the light flux increases due to excited-state up-conversion losses. Furthermore, such phosphors may exhibit a pump- dependent color shift (e.g. for white LED lighting) where the phosphors exhibit differential droop. Hence, it is desired to provide a light generating system with less or low (differential) droop. Additionally or alternatively, it is desired to provide a light generating system with tunable color temperature and/or tunable spectral properties while limiting (differential) droop. Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. According to a first aspect, the invention provides a light generating system configured to provide system light. In embodiments, the light generating system may comprise n1 first light generating devices, n2 second light generating devices, and a luminescent arrangement. Especially, the n1 first light generating devices may comprise one or more first solid state light sources. Further, the n1 first light generating devices may especially be configured to generate first device light having a first centroid wavelength (λc1). In further embodiments, the first centroid wavelength (λc1) may be selected from the wavelength range of 400-540 nm. In embodiments, n1≥1. Further, in embodiments, the n2 second light generating devices may comprise one or more second solid state light sources. Especially, the n2 second light generating devices may be configured to generate second device light having a second centroid wavelength (λc2). In further embodiments, the second centroid wavelength (λc2) may be selected from the wavelength range of 400-540 nm. In embodiments, n2≥1. Furthermore, in embodiments, the luminescent arrangement may comprise (i) a first luminescent material configured to convert at least part of the first device
2023PF80227 3 light and/or at least part of the second device light received by the first luminescent material into first luminescent material light, and (ii) a second luminescent material configured to convert at least part of the first device light and/or at least part of the second device light received by the second luminescent material into second luminescent material light. Here, the first luminescent material may in embodiments comprise a luminescent material of the type MxM’2-2xAaX6 doped with tetravalent manganese. Further, in embodiments, the second luminescent material may comprise a luminescent material of the type MxM’2-2xAbX6 doped with tetravalent manganese, especially wherein M comprises an alkaline earth cation, M’ comprises an alkaline cation, x is in the range of 0-1, Aa and Ab comprise a tetravalent cation, and wherein X comprises a monovalent anion, at least comprising fluorine, and wherein Aa comprises a higher molar percentage of Si than Ab, and wherein Ab comprises a higher molar percentage of Ti than Aa. Further, specifically, Aa of the first luminescent material and Ab of the second luminescent material comprise one or more elements selected from the group of Si, Ti, Ge, Sn, and Zr, wherein Aa at least comprises Si and Ab at least comprises Ti. Further, specifically, M’ comprises one or more elements selected from the group Li, Na, K, Rb and Cs. In embodiments, the first centroid wavelength (λc1) may be selected such that an absorption by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an absorption by the second luminescent material (at this first centroid wavelength (λc1)), and the second centroid wavelength (λc2) may be selected such that an absorption by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an absorption by the first luminescent material (at this second centroid wavelength (λc2)). Especially, it may apply that |λc2-λc1|≥15 nm. In embodiments, the system light may comprise one or more of the first luminescent material light and the second luminescent material light. Hence, in specific embodiments, the invention may provide a light generating system configured to provide system light, wherein the light generating system comprises n1 first light generating devices, n2 second light generating devices, and a luminescent arrangement, wherein: (I) the n1 first light generating devices comprises one or more first solid state light sources, wherein the n1 first light generating devices are configured to generate first device light having a first centroid wavelength (λc1), wherein the first centroid wavelength (λc1) is selected from the wavelength range of 400-540 nm, and wherein n1≥1; (II) the n2 second light generating devices comprise one or more second solid state light sources, wherein the n2 second light generating devices are configured to generate second device light having a second centroid wavelength (λc2), wherein the second centroid wavelength (λc2) is selected from the wavelength range of 400-540 nm, and wherein n2≥1;
2023PF80227 4 (III) the luminescent arrangement comprises (i) a first luminescent material configured to convert at least part of the first device light and/or at least part of the second device light received by the first luminescent material into first luminescent material light, and (ii) a second luminescent material configured to convert at least part of the first device light and/or at least part of the second device light received by the second luminescent material into second luminescent material light, wherein the first luminescent material comprises a luminescent material of the type MxM’2-2xAaX6 doped with tetravalent manganese, wherein the second luminescent material comprises a luminescent material of the type MxM’2-2xAbX6 doped with tetravalent manganese; wherein M comprises an alkaline earth cation, M’ comprises an alkaline cation, x is in the range of 0-1, Aa and Ab comprise a tetravalent cation wherein Aa at least comprises Si and Ab at least comprises Ti, and wherein X comprises a monovalent anion, at least comprising fluorine; and wherein Aa comprises a higher molar percentage of Si than Ab, and wherein Ab comprises a higher molar percentage of Ti than Aa; (IV) the first centroid wavelength (λc1) is selected such that an absorption by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an absorption by the second luminescent material (at this first centroid wavelength (λc1)), and wherein the second centroid wavelength (λc2) is selected such that an absorption by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an absorption by the first luminescent material (at this second centroid wavelength (λc2)), and wherein |λc2-λc1|≥15 nm; and (V) the system light comprises one or more of the first luminescent material light and the second luminescent material light. Specifically, Aa of the first luminescent material and Ab of the second luminescent material comprise one or more elements selected from the group of Si, Ti, Ge, Sn, and Zr, wherein Aa at least comprises Si and Ab at least comprises Ti. Further, specifically, M’ comprises one or more elements selected from the group Li, Na, K, Rb and Cs. Such a light generating system may comprise at least two different types of luminescent material in a single element. The luminescent material may facilitate, in combination with a (blue) light source, the generation of white light. Hence, with two different types of light sources (having a different centroid wavelength) and two different types of luminescent material, respectively, the percentage of blue contribution to the system light and/or the percentage of luminescent material light contribution to the system light may be (individually) controlled. That is, in embodiments the correlated color temperature (CCT) of the system light provided may be controlled. Further, (both of) the two different types of luminescent material may be illuminated by the first device light and/or the second device
2023PF80227 5 light. Therefore, differential droop between the two types of luminescent material may be compensated by controlling radiant fluxes of the first device light and/or the second device light. In this way, an undesired shift in the color point and/or the color rendering index (CRI) of the system light may be reduced. Hence, in a further embodiment, the invention may provide a PC-LED lighting device comprising a plurality of phosphors with differential phosphor pumping. As mentioned above, the light generating system may comprise n1 first light generating devices, n2 second light generating devices, and a luminescent arrangement. In embodiments, the n1 first light generating devices may comprise one or more first solid state light sources. Analogously, in embodiments, the n2 second light generating devices may comprise one or more second solid state light sources. See further also below. In embodiments, the luminescent arrangement may comprise a luminescent body further comprising a matrix material and one or more luminescent materials. Here, the matrix material may especially be an “optically transparent” polymeric material, such as selected from the group comprising polydimethylsiloxane (PDMS), polymethylphenyl- siloxane (PMPS), and polydiphenylsiloxane (PDPS), especially PDMS. The term “optically transparent” refers to materials that may be transmissive for one or more wavelengths selected from the range of 190-1500 nm, such as for one or more wavelengths selected from the range of 200-1000 nm, especially for one or more wavelengths selected from the range of 380-780 nm. Further, in embodiments, the luminescent arrangement may be configured as a luminescent layer, or a luminescent encapsulant (at least partly) surrounding the first light generating devices and the second light generating devices. In embodiments, the luminescent arrangement may comprise a first luminescent material and a second luminescent material. Especially, (both) the first luminescent material and the second luminescent material may be configured in a light receiving relationship with the first light generating device and/or the second light generating device. In embodiments, the first luminescent material may be configured to convert at least part of the first device light and/or at least part of the second device light received by the first luminescent material into first luminescent material light. Further, in embodiments, the second luminescent material may be configured to convert at least part of the first device light and/or at least part of the second device light received by the second luminescent material into second luminescent material light. In embodiments, the first luminescent material may comprise a luminescent material of the type MxM’2-2xAaX6 doped with tetravalent manganese. Further, in
2023PF80227 6 embodiments, the second luminescent material may comprise a luminescent material of the type MxM’2-2xAbX6 doped with tetravalent manganese. Here, M may comprise an alkaline earth cation, M’ may comprise an alkaline cation, x may be in the range of 0-1, Aa and Ab may comprise a tetravalent cation, and wherein X may comprise a monovalent anion, at least comprising fluorine, and Aa may comprise a higher molar percentage of Si than Ab, and Ab may comprise a higher molar percentage of Ti than Aa. See further also below. To achieve a wide color gamut and high efficiency, the luminescent material should have a relatively high x value or y value in chromaticity coordinate. The terms “chromaticity coordinates” and “color gamut” are known in the art. In general, transition metal Mn4+ activated phosphors (especially K2(Si/Ge/Ti)F6 fluoride red phosphors) may facilitate a wide color gamut due to the relatively deep red color. Luminescence characteristics of Mn4+ lies in its 3d3 electronic state, caused by the crystal field splitting of 3d energy level orbitals and electron distribution within octahedron structure. Its luminous properties are mainly dependent on spin forbidden transitions between 2E 4 g and A2g energy levels, and typically exhibit broadband excitation and peak line spectral emission ranging from 600 to 650 nm, and are only marginally influenced by the chemical environment of the Mn4+ ion. Whereas the spectral power distribution of the emission spectrum may be relatively independent from the chemical environment of the Mn4+ ion, the excitation spectrum, however, may substantially depend on the chemical environment of the Mn4+ ion. Hence, in specific embodiments, (at least) two different luminescent species may herein be applied, wherein MxM’2-2xAaX6 may comprise K2SiF4 and MxM’2-2xAbX6 may comprise K2TiF4. Hence, the first luminescent material and the second luminescent material may have essentially the same output spectra. Hence, in such embodiments, the first luminescent material light may have the same spectral distribution as the second luminescent material light. The first luminescent material may in embodiments have relatively high absorption for the first centroid wavelength (λc1) (in the blue-green wavelength range). Analogously, the second luminescent material may have relatively high absorption for the second centroid wavelength (λc2) (in the blue-green wavelength range). Therefore, in embodiments, the n1 first light generating devices may be configured to generate first device light having the first centroid wavelength (λc1). Nevertheless, the first luminescent material may in embodiments also have absorption for the second centroid wavelength (λc2) (in the blue-green wavelength range), and/or the second luminescent material may in embodiments also have absorption for the first centroid wavelength (λc1) (in the blue-green wavelength
2023PF80227 7 range). Note that in this wavelength range for these luminescent materials the excitation spectrum may scale with the absorption spectrum (i.e.2x higher absorption, therefore also 2x better excitability, etc.). Hence, in embodiments the phrase “the first centroid wavelength (λc1) is selected such that an absorption by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an absorption by the second luminescent material λc1, and wherein the second centroid wavelength (λc2) is selected such that an absorption by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an absorption by the first luminescent material”, and similar phrases, may also refer to embodiments wherein the first centroid wavelength (λc1) is selected such that an excitation by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an excitation by the second luminescent material λc1, and wherein the second centroid wavelength (λc2) is selected such that an excitation by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an excitation by the first luminescent material. In these phrases, and similar phrases, instead of the term “absorption” also the term “absorption value” may be applied and/or instead of the term “excitation” also the term “absorption value” may be applied. In the wavelength range of about 400-500 nm, both the first luminescent material and the second luminescent material have an absorption band or excitation band, related to the 4A2-4T2 transition. Hence, for comparing the absorption (value) or the excitation (value), in embodiments the spectra may be normalized to the peak (or peak maximum) of the respective 4A2-4T2 transition. Therefore, especially in embodiments the phrase “the first centroid wavelength (λc1) is selected such that an absorption by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an absorption by the second luminescent material λc1, and wherein the second centroid wavelength (λc2) is selected such that an absorption by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an absorption by the first luminescent material”, and similar phrases, may also refer to embodiments wherein the first centroid wavelength (λc1) is selected such that an excitation by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an excitation by the second luminescent material λc1, and wherein the second centroid wavelength (λc2) is selected such that an excitation by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an excitation by the first luminescent material, wherein the excitation (value) is determined from excitation spectra
2023PF80227 8 normalized to the (peak of the) excitation band in the 400-500 nm wavelength range (i.e. the 4A2-4T2 transition). Especially, the first centroid wavelength (λc1) may be selected from the wavelength range of 400-540 nm, such as from the wavelength range of 425-443 nm, especially from the wavelength range of 430-440 nm. Analogously, the n2 second light generating devices may be configured to generate second device light having the second centroid wavelength (λc2). In further embodiments, the second centroid wavelength (λc2) may be selected from the wavelength range of 400-540 nm, such as from the wavelength range of 465-525 nm, especially from the wavelength range of 500-525 nm, more especially from the wavelength range of 500-510 nm. Additionally, in order to facilitate tunability of the CCT (of the system light), it may be advantageous to select the first centroid wavelength (λc1) different from the second centroid wavelength (λc2). Especially, |λc2-λc1|≥10 nm, such as |λc2-λc1|≥15 nm. Yet, in embodiments |λc2-λc1|≥20 nm. In specific embodiments, |λc2-λc1|≥25 nm. Yet, in embodiments |λc2-λc1|≥25 nm Further, especially the first centroid wavelength (λc1) may be selected from the wavelength range of 425-443 nm, and wherein the second centroid wavelength (λc2) is selected from the wavelength range of 465-525 nm. With two different centroid wavelengths, the percentage composition of light in the blue-green wavelength range comprised by the system light may be controlled. That is, the proportion of the first device light and the second device light comprised by the system light may be varied. Thus, the spectral distribution (and CCT) of the system light may be controlled. The term “centroid wavelength”, also indicated as λc, is known in the art, and refers to the wavelength value where half of the light energy is at shorter and half the energy is at longer wavelengths; the value is stated in nanometers (nm). It is the wavelength that divides the integral of a spectral power distribution into two equal parts as expressed by the formula λc = Σ λ*I(λ) / (Σ I(λ), where the summation is over the wavelength range of interest, and I(λ) is the spectral energy density (i.e. the integration of the product of the wavelength and the intensity over the emission band normalized to the integrated intensity). The centroid wavelength may e.g. be determined at operation conditions. Since, the first luminescent material may have an at least as high, or (thus also) even relatively higher absorption for the first centroid wavelength (λc1) than the second luminescent material has, and the second luminescent material may have a relatively higher absorption for the second centroid wavelength (λc2) than the first luminescent material has, it may be desired to select the first centroid wavelength (λc1) and the second centroid
2023PF80227 9 wavelength (λc2) such that the (outcoupled) system light comprises first luminescent material light of relatively high intensity and/or second luminescent material light of relatively high intensity. Hence, in embodiments, the first centroid wavelength (λc1) may be selected such that an absorption by the first luminescent material at this first centroid wavelength (λc1) is at least as high as an absorption by the second luminescent material (at this first centroid wavelength (λc1)), and the second centroid wavelength (λc2) may be selected such that an absorption by the second luminescent material at this second centroid wavelength (λc2) is relatively higher than an absorption by the first luminescent material (at this second centroid wavelength (λc2). Hence, the first luminescent material may have a different absorption spectrum compared to the second luminescent material. For a given first centroid wavelength (λc1) selected from a predefined wavelength range, the first luminescent material may have an equal or higher absorption (i.e., “at least as high as an absorption”) for said first centroid wavelength (λc1) compared to the second luminescent material. For a given second centroid wavelength (λc2) selected from a predefined wavelength range, the second luminescent material may have a higher absorption (i.e., “a relatively higher absorption”) for said second centroid wavelength (λc2) compared to the first luminescent material. By controlling the radiant fluxes of the first light generating devices and the second light generating devices, droop (of effectively (at least part of) the system light) may be reduced, delayed, or even essentially prevented. In embodiments, one or more of the following may apply: (i) at least a part of the first device light may be converted to the first luminescent material light and the second luminescent material light, and (ii) at least a part of the second device light may be converted to the first luminescent material light and the second luminescent material light. Therefore, in embodiments, the system light may comprise the first luminescent material light and the second luminescent material light. Note that, in embodiments, the light generating system may be configured such that part of the first device light and/or the second device light may be transmitted (without a conversion) via the luminescent arrangement. Therefore, in embodiments, the system light may (also) comprise (at least a part of) the first device light and (at least a part of) the second device light. In summary, the light generating system may in embodiments be configured to generate the system light comprising (at least part of) one or more of the first luminescent material light, the second luminescent material light, the first device light, and the second device light. Note, however, that when choosing the second centroid wavelength relatively high, such as at minimum about 500 nm, it may be possible to
2023PF80227 10 provide system light without first luminescent material light when the first light generating devices would not provide first device light. Conversely, in some embodiments, the first device light and/or the second device light may undergo complete conversion to luminescent material light (i.e., the first luminescent material light and the second luminescent material light). In such embodiments, the system light may consist of the first luminescent material light and the second luminescent material light. In such embodiments, addition of a blue luminescent material and/or a further blue emitting light generating device (see also below) may be desirable when the system light should be white light (see further below). As indicated above, in embodiments the system light may be white light. White light may be provided by mixing the unconverted device light (i.e., the first device light and/or the second device light) with the luminescent material light (i.e., the first luminescent material light and/or the second luminescent material light). In specific embodiments, the first device light (and/or) the second device light may comprise light in the blue-green wavelength range, and the first luminescent material light (and/or the second luminescent material light) may comprise light in the orange-red wavelength range. Hence, by mixing orange-red light, blue light, and (optionally) light of a further source, white light may be provided. The further source may comprise, as indicated above, an additional light generating device and/or an additional luminescent material. Especially, the further source of light may provide light having intensity in at least part of the green-yellow wavelength range. The terms “green-yellow wavelength range” or “green-yellow emission” may especially relate to light having a wavelength in the range of about 495-590 nm. The term “orange-red wavelength range” may especially relate to light having a wavelength in the range of about 590-780 nm, especially (at least) in the range of about 590-680 nm. In embodiments, system light may be white light having a correlated color temperature selected from the range of 1500-6500 K, such as 1700-6500 K. Yet, in embodiments the system light may be white light having a correlated color temperature selected from the range of 1500-3000 K, such as 1700-2700 K. Furthermore, in embodiments, the system light may have a color rendering index of at least 75, such as at least about 80, especially at least 90. Hence, in specific embodiments, the system light is white light having a correlated color temperature selected from the range of 1500-6500 K and a color rendering index of at least 80. The term “white light” herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 1500 K and 20000 K, such as between 1700 and 20000 K, especially in
2023PF80227 11 embodiments 2700-20000 K, for general lighting especially in the range of about 1800 K and 6500 K. Yet further, in embodiments the correlated color temperature (CCT) is especially 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. The terms CCT and CRI are known in the art. It may be desirable to control both the CCT and the CRI of the (outcoupled) system light. Furthermore, it may be desirable to control the spectral distribution/composition of the outcoupled system light. Especially, it may be desirable to control the proportion of two or more of the first device light, the second device light, the first luminescent material light, the second luminescent material light, and the light of the optional further source, relative to one another. Here below, by way of embodiments, some such advantageous configurations are described. As mentioned above, the luminescent arrangement may comprise a luminescent body. The luminescent body may e.g. comprise a (coating) layer or a plate(let). In embodiments, the luminescent body may comprise first luminescent material particles (comprising the first luminescent material) embedded in a matrix material. Especially, the luminescent body may comprise the first luminescent material particles in a first weight percentage C1. Analogously, the luminescent body may comprise the second luminescent particles (comprising the second luminescent material) embedded in the matrix material. Especially, the luminescent body may comprise the second luminescent material particles in a second weight percentage C2. Here, the first weight percentage C1 may especially refer to a w/w% the weight of first luminescent material particles relative to the weight of the luminescent body. Analogously, the second weight percentage C2 may especially refer to a w/w% the weight of second luminescent material particles relative to the weight of the luminescent body. In embodiments, the weight of the luminescent body may essentially be the combined weight of (i) the matrix material, (ii) the first luminescent particles, (iii) the second luminescent particles, and (optionally) (iv) the third luminescent material (see further below), though further materials comprised by the luminescent body are not excluded, like scattering particles, yet further luminescent materials, etc. The percentage of the first device light and/or the second device light converted to the first luminescent material light may be dependent on the first weight percentage C1 relative to a composition (of the luminescent body). Analogously, the percentage of the first device light and/or the second device light converted to the second luminescent light may be dependent on the second weight percentage C2 relative to the
2023PF80227 12 composition (of the luminescent body). In embodiments, the luminescent body may comprise both the first luminescent material and the second luminescent material. Especially, C1+C2 may be at least 10%, such as at least 15%, especially at least 20%. Further, in embodiments, C1+C2 may be at most 100%, such as at most 90%, especially at most 80%. In some embodiments, the luminescent body may essentially consist of the first luminescent material and the second luminescent material i.e., C1+C2=100%. Hence, in embodiments, it may apply that 10%≤C1+C2≤100%, such as 15%≤C1+C2≤90%, especially 20%≤C1+C2≤80%. In embodiments, 10%≤C1+C2≤40% may apply. Furthermore, the percentage of first luminescent material light (comprised by the system light) may in embodiments be increased relative to the percentage of second luminescent material light (comprised by the system light), by increasing the first weight percentage C1 relative to the second weight percentage C2. Analogously, the percentage of second luminescent material light (comprised by the system light) may in embodiments be increased relative to the percentage of first luminescent material light (comprised by the system light), by increasing the second weight percentage C2 relative to the first weight percentage C1. In embodiments, it may apply that C1/C2 is at least 0.33, such as at least 0.5, especially at least 0.67, more especially at least 0.83. Further, in embodiments C1/C2 may be at most 3, such as at most 2, especially at most 1.5, more especially at most 1.2. Hence, in embodiments, C1 and C2 may be selected such that 0.33≤C1/C2≤3, such as 0.5≤C1/C2≤2, especially 0.67≤C1/C2≤1.5, more especially 0.83≤C1/C2≤1.2. Further, the percentages of first luminescent material light and the second luminescent material light in the system light may (also) be dependent upon a concentration of the tetravalent manganese dopant in its host material. In embodiments, these concentrations may be selected from the range of 0.1-15 % (relative to the total of tetravalent cation A (i.e., relative to Aa in the first luminescent material or relative to Ab in the second luminescent material). In embodiments, they may essentially be the same (see also below). In some embodiments, to compensate for the relatively higher absorption in the blue-green wavelength range by the second luminescent material compared to the first luminescent material, the first weight percentage C1 may be selected to be larger than the second weight percentage C2. Especially, C1 and C2 may be selected such that 1<C1/C2≤3, such as 1<C1/C2≤2, especially 1<C1/C2≤1.5. Further in embodiments, C1 ≥ 1.25*C2, such as C1 ≥ 1.5*C2, especially C1 ≥ 1.75*C2. Yet further, in embodiments, C1 ≤ 3.5*C2, such as C1 ≤ 3.25*C2, especially C1 ≤ 3*C2. Hence, in specific embodiments, the luminescent arrangement comprises a composition comprising the first luminescent material with a first weight
2023PF80227 13 percentage C1 relative to the composition and the second luminescent material with a second weight percentage C2 relative to the composition, wherein 1<C1/C2≤2 (and wherein 10%≤C1+C2≤100% (such as in embodiments 10%≤C1+C2≤90%). To increase the percentage of first device light comprised by the system light, the luminescent arrangement may in embodiments be selected such that a part of first device light is not converted by the luminescent arrangement. Especially, at least 10%, such as at least 20%, especially at least 30% of the first device light may not be converted by the luminescent arrangement. Further, in embodiments, at most 90%, such as at most 80%, especially at most 70% of the first device light may not be converted by the luminescent arrangement. Analogously, to increase the percentage of second device light comprised by the system light, the luminescent arrangement may in embodiments be selected such that a part of second device light is not converted by the luminescent arrangement. Especially, at least 10%, such as at least 20%, especially at least 30% of the second device light may not be converted by the luminescent arrangement. Further, in embodiments, at most 90%, such as at most 80%, especially at most 70% of the second device light may not be converted by the luminescent arrangement. Of course, in embodiments, a part of the light incident on the luminescent arrangement may be transmitted, reflected, scattered, or lost internally by the luminescent arrangement. However, in specific embodiments, the term “a part of the light may not be converted” may refer to the part of the device light transmitted via the luminescent arrangement. Hence, in specific embodiments, the luminescent arrangement is configured such that (i) selected from the range of 10-90% of the first device light is not converted by the luminescent arrangement and selected from the range of 10-90% of the second device light is not converted by the luminescent arrangement. For instance, assuming a transmissive mode, the luminescent arrangement (including thickness of e.g. a luminescent body and concentrations of the respective luminescent materials) as well as the centroid wavelengths of the first light generating devices and second light generating devices may be selected such that part of the respective device light is converted and part of the respective device light is transmitted (and may end up in the system light). The light generating system may comprise at least one first light generating device. In further embodiments, the light generating system may comprise a plurality of first light generating devices. Especially, n1≥1, such as n1≥2, especially n1≥5, more especially n1≥10. Further, in embodiments, n1≤20, such as n1≤18, especially n1≤15. However, n1 may also have other values. Analogously, the light generating system may comprise at least one second light generating device. In further embodiments, the light generating system may
2023PF80227 14 comprise a plurality of second light generating devices. Especially, n2≥1, such as n2≥2, especially n2≥5, more especially n2≥10. Further, in embodiments, n2≤20, such as n2≤18, especially n2≤15. However, n2 may also have other values. Especially, in embodiments 0.33≤n1/n2≤3, such as 0.5≤n1/n2≤2, especially 0.67≤n1/n2≤1.5, more especially 0.83≤n1/n2≤1.2. Further, the percentage of first device light relative to the percentage of the second device light) in the system light may in embodiments be controlled by controlling their radiant fluxes. This may in embodiments imply that more first light generating devices than second light generating devices, or more second light generating devices than first light generating devices provide their device light to the luminescent arrangement. In further embodiments, the ratio of the radiant flux of first device light to the radiant flux of second device light generated may be varied in dependence of the ratio of n1 to n2. In embodiments, n1 may be selected larger than n2 to compensate for the relatively higher absorption in the blue-green wavelength range by the second luminescent material compared to the first luminescent material (i.e., to increase the percentage of the first device light as compared to the second device light). Therefore, n1 and n2 may especially be selected such that n1 is larger than n2. Especially, n1/n2 may be at least 1.15, such as at least 1.20, especially at least 1.25. Further, in embodiments, n1/n2 may be at most 3, such as at most 2. Hence, in embodiments, n1 and n2 may be selected such that 1<n1/n2≤3, such as 1<n1/n2≤2, especially 1.25<n1/n2≤2. However, other ratios may also be possible. Amongst others it may be desired to increase the color gamut of the light generating system. Here, color gamut refers to the subset of colors which can be accurately represented by the light generating system. This may especially be facilitated by means of the additional (third) light generating device and/or the third luminescent material (see also above). In further embodiments, the light generating system may comprise n3 third light generating devices configured to generate third device light. Especially, the n3 third light generating devices may comprise one or more third solid state light sources. Alternatively or additionally, the luminescent arrangement may comprise a third luminescent material. The additional third device light and/or third luminescent material light may facilitate improving the color gamut of the light generating system. Hence, in specific embodiments, the light generating system may comprise one or more third light generating devices configured to generate third device light having spectral power at one or more wavelengths selected from one or more of the blue wavelength range, the green wavelength range, the yellow wavelength range, the orange wavelength range, and the red wavelength range. In yet further
2023PF80227 15 embodiments, third device light and/or the (third luminescent material) light generated by the third luminescent material may (independently) have a spectral power at one or more wavelengths selected from one or more of the violet wavelength range, the cyan wavelength range, the pink wavelength range, and the amber wavelength range, though other wavelength ranges may also be possible. As indicated above, in embodiments, the light generating device may (thus) comprise a third luminescent material. The third luminescent material may be configured to convert one or more of (i) the first device light, (ii) the second device light, and (iii) the optional third device light into third luminescent material light. Especially, the third luminescent material light may have a different spectral power distribution from (both) the first luminescent material light and the second luminescent material light. Hence, in specific embodiments, one or more of the following applies: (I) at least part of the system light comprises one or more of (i) non-converted first device light and (ii) non-converted first device light, (II) the luminescent arrangement comprises a third luminescent material configured to convert at least part of one or more of (i) the first device light, (ii) the second device light, and (iii) light of a further light generating device into third luminescent material light having a spectral power distribution different from the first luminescent material light and the second luminescent material light, and (III) the light generating system comprises one or more third light generating devices configured to generate third device light. The terms “violet light” or “violet emission” especially relates to light having a wavelength in the range of about 380-440 nm. The terms “blue light” or “blue emission” especially relates to light having a wavelength in the range of about 440-495 nm (including some violet and cyan hues). The terms “green light” or “green emission” especially relate to light having a wavelength in the range of about 495-570 nm. The terms “yellow light” or “yellow emission” especially relate to light having a wavelength in the range of about 570- 590 nm. The terms “orange light” or “orange emission” especially relate to light having a wavelength in the range of about 590-620 nm. The terms “red light” or “red emission” especially relate 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. The term “cyan” may refer to one or more wavelengths selected from the range of about 490-520 nm. The term “amber” may refer to one or more wavelengths selected from the range of about 585-605 nm, such as about 590-600 nm. The phrase “light having one or more wavelengths in a wavelength range” and similar phrases may especially indicate that the indicated light (or
2023PF80227 16 radiation) has a spectral power distribution with at least intensity or intensities at these one or more wavelengths in the indicated wavelength range. For instance, a blue emitting solid state light source will have a spectral power distribution with intensities at one or more wavelengths in the 440-495 nm wavelength range. Returning to aspects and features relating to the one or more types of luminescent materials configured in the light generating system, here below, a description of luminescent materials is provided. The general term “luminescent material” may especially refer to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation. In general, the first radiation and second radiation have different spectral power distributions. Hence, instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” may be applied. In general, the second radiation has a spectral power distribution at larger wavelengths than the first radiation, which is the case in so-called down-conversion. In specific embodiments, however, the second radiation has a spectral power distribution with intensity at smaller wavelengths than the first radiation, which is the case in so-called up-conversion. In embodiments, the “luminescent material” may especially refer to a material that can convert radiation into e.g. visible and/or infrared light. For instance, in embodiments the luminescent material may be able to convert one or more of UV radiation and blue radiation, into visible light. The luminescent material may in specific embodiments also convert radiation into infrared radiation (IR). Hence, upon excitation with radiation, the luminescent material emits radiation. In general, the luminescent material will be a down converter, i.e. radiation with a smaller wavelength is converted into radiation with a larger wavelength (λex<λem), though in specific embodiments the luminescent material may comprise up-converter luminescent material, i.e. radiation with a larger wavelength is converted into radiation with a smaller wavelength (λex>λem). In embodiments, the term “luminescence” may refer to phosphorescence. In embodiments, the term “luminescence” may also refer to fluorescence. Instead of the term “luminescence”, also the term “luminescent material light” or “emission” may be applied. Hence, the terms “first radiation” and “second radiation” may refer to excitation radiation and emission (radiation), respectively. Likewise, the term “luminescent material” may in embodiments refer to phosphorescence and/or fluorescence. The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material
2023PF80227 17 composition. Instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art. In embodiments, luminescent materials are selected from garnets and nitrides, especially doped with trivalent cerium or divalent europium, respectively. The term “nitride” may also refer to oxynitride or nitridosilicate, etc. Alternatively or additionally, the luminescent material(s) may be selected from silicates, especially doped with divalent europium. As mentioned before, in embodiments, the luminescent arrangement may comprise a luminescent body, which may comprise a matrix material. In further embodiments, the third luminescent material may be embedded in the matrix material may. For instance, the matrix material may host third luminescent particles (comprising the third luminescent material). The term “third luminescent material” may also refer to two or more different types of third luminescent material. In embodiments, the third luminescent particles may comprise a divalent europium comprising oxynitride luminescent material. Further, in embodiments, the third luminescent material may comprise a divalent europium comprising nitride luminescent material. In specific embodiments, the third luminescent material may be selected from a divalent europium comprising oxynitride luminescent material and a divalent europium comprising nitride luminescent material. Hence, in specific embodiments, the matrix material may comprise a third luminescent material, wherein the third luminescent material may be selected from a divalent europium comprising oxynitride luminescent material and a divalent europium comprising nitride luminescent material. In specific embodiments, the luminescent material (especially the third luminescent material) may at least comprise a luminescent material of the type A3B5O12:Ce3+, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc. Especially, A may comprise one or more of Y, Gd and Lu, such as especially one or more of Y and Lu. Especially, B may comprise one or more of Al and Ga, more especially at least Al, such as essentially entirely Al. Hence, especially suitable luminescent materials are cerium comprising garnet materials. Embodiments of garnets especially include A3B5O12 garnets, wherein A comprises at least yttrium (Y) or lutetium (Lu) and wherein B comprises at least aluminum (Al). Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B may comprise aluminum (Al); however, in addition to aluminum, B may also partly comprise gallium (Ga) and/or scandium (Sc) and/or
2023PF80227 18 indium (In), especially up to about 20% of B, more especially up to about 10 % of B (i.e. the B ions essentially consist of 90 or more mole % of Al and 10 or less mole % of one or more of Ga, Sc and In); B may especially comprise up to about 10% gallium. In another variant, B and O may at least partly be replaced by Si and N. The element A may especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and/or Tb are especially only present up to an amount of about 20% of A. In a specific embodiment, the garnet luminescent material comprises (Y1-xLux)3B5O12:Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1. The term “:Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the “A” ions) in the luminescent material is replaced by Ce. For instance, in the case of (Y1-xLux)3Al5O12:Ce, part of Y and/or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will replace A in general for not more than 10%; in general, the Ce concentration will be in the range of 0.1 to 4%, especially 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the full correct formula could be (Y0.1Lu0.89Ce0.01)3Al5O12. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art. In embodiments, the luminescent material (thus) comprises A3B5O12 wherein in specific embodiments at maximum 10% of B-O may be replaced by Si-N. Here, B in B-O refers to one or more of Al, Ga, In and Sc (and O refers to oxygen); in specific embodiments B-O may refer to Al-O. As indicated above, in specific embodiments x3 may be selected from the range of 0.001-0.04. Especially, such luminescent materials may have a suitable spectral distribution (see however below), have a relatively high efficiency, have a relatively high thermal stability, and allow a high CRI (optionally in combination with (the) light of other sources of light as described herein). Hence, in specific embodiments A may be selected from the group consisting of Lu and Gd. Alternatively or additionally, B may comprise Ga. Hence, in embodiments the luminescent material comprises (Yx1(Lu,Gd)x2Cex3)3(Aly1Gay2)5O12, wherein Lu and/or Gd may be available. Even more especially, x3 is selected from the range of 0.001-0.1, wherein 0<x2+x3≤0.1, and wherein 0≤y2≤0.1. Further, in specific embodiments, at maximum 1% of B-O may be replaced by Si- N. Here, the percentage refers to moles (as known in the art); see e.g. also EP3149108. In yet further specific embodiments, the luminescent material comprises (Yx1Cex3)3Al5O12, wherein x1+x3=1, and wherein 0<x3≤0.2, such as 0.001-0.1. In specific embodiments, the third luminescent material may only include luminescent materials selected from the type of cerium comprising garnets. In even further specific embodiments, the third luminescent material may include a single type of
2023PF80227 19 luminescent material, such as (Yx1A’x2Cex3)3(Aly1B’y2)5O12. Hence, in specific embodiments the third luminescent material may comprise luminescent material, wherein at least 85 weight%, even more especially at least about 90 wt.%, such as yet even more especially at least about 95 weight % of the luminescent material comprises (Yx1A’x2Cex3)3(Aly1B’y2)5O12. Here, A’ comprises one or more elements selected from the group consisting of lanthanides, and B’ comprises one or more elements selected from the group consisting of Ga, In and Sc, wherein x1+x2+x3=1, wherein x3>0, wherein 0<x2+x3≤0.2, wherein y1+y2=1, wherein 0≤y2≤0.2. Especially, x3 is selected from the range of 0.001-0.1. Note that in embodiments x2=0. Alternatively or additionally, in embodiments y2=0. Further, in embodiments, the third luminescent material may include a luminescent material such as (Yx11Lux12A’x13Cex14)3B5O12, wherein x11+x12+x13+x14=1, wherein x14 may be selected from the range of 0.001-0.1. Further, in embodiments, the third luminescent material may comprise at least two luminescent materials of the type A3B5O12:Ce3+, such as at least (Yx11Lux12A’x13Cex14)3B5O12 and (Yx21Lux22A’x23Cex24)3B5O12. In such embodiments, the third luminescent material may comprise a primary third luminescent material such as (Yx11Lux12A’x13Cex14)3B5O12, wherein x11 ≥ x12, wherein 0.001 ≤ x14 ≤ 0.1, wherein A’ comprises one or more of La, Gd, and Tb, and wherein B comprises one or more of Al, Ga, In, and Sc. Further, in such embodiments, the third luminescent material may comprise a secondary third luminescent material such as (Yx21Lux22A’x23Cex24)3B5O12, wherein x21+x22+x23+x24=1, wherein x22 > x12, wherein 0.001 ≤ x24 ≤ 0.1, wherein A’ comprises one or more of La, Gd, and Tb, and wherein B comprises one or more of Al, Ga, In, and Sc. Hence, in specific embodiments, the third luminescent material comprises a primary third luminescent material of the type (Yx11Lux12A’x13Cex14)3B5O12 and a secondary third luminescent material of the type (Yx21Lux22A’x23Cex24)3B5O12, wherein A’ comprises one or more of La, Gd, and Tb, wherein B comprises one or more of Al, Ga, In and Sc; and wherein: (I) x11+x12+x13+ x14=1; x11+x12>0; 0≤x13<1; and 0.001≤x14≤0.1; (II) x21+x22+x23+ x24=1; x21+x22>0; 0≤x23<1, and 0.001≤x24≤0.1; and (III) x11>x21 and x22>x12. In embodiments, the secondary third luminescent material may thus comprise on a molar basis more Lu than the primary third luminescent material. Further, in embodiments, the primary third luminescent material may comprise on a molar basis more Y than the secondary third luminescent material, x11 > x21. In embodiments, x12 may be equal to zero. Further, in embodiments, one or more of x12, x13, and x23 may be equal to zero. In embodiments, x14 may be equal to x24. Yet, in embodiments, x14 may be different from x24,
2023PF80227 20 wherein (both) x14 and x24 may be individually selected from the range of 0.001-0.1. Hence, in embodiments, the third luminescent material may comprise a primary third luminescent material such as (Yx11Lux12Cex14)3B5O12 (wherein x11+ x12+ x14 = 1) and a secondary third luminescent material such as (Yx21Lux22Cex24)3B5O12 (wherein x21+ x22+ x24 = 1), wherein x22 > x12, and wherein in specific embodiments x12 = 0. Hence, in specific embodiments, the third luminescent material may comprise at least two luminescent materials of the type A 3+ 3B5O12:Ce , wherein: (a) a primary third luminescent material of this type may comprise on a molar basis more Y than a secondary third luminescent material of this type, and (b) the secondary third luminescent material of this type may comprise on a molar basis more Lu than the primary third luminescent material of this type. Further, in embodiments, the third luminescent material may include a luminescent material such as Lux1A’x2Cex3)3(Aly1B’y2)5O12, where x1, x2, x3, y1, and y2 are as defined above. Especially, in embodiments, x1+x2+x3=1, wherein x1≥0.5. Further, in embodiments, the third luminescent material may comprise at least two luminescent materials of the type A3B5O12:Ce3+, such as at least (Yx1A’x2Cex3)3(Aly1B’y2)5O12 and Lux1A’x2Cex3)3(Aly1B’y2)5O12. In such embodiments, the third luminescent material may comprise a primary third luminescent material such as (Yx1A’x2Cex3)3(Aly1B’y2)5O12, wherein x1+x2+x3=1, wherein x1≥0.5, wherein A’ comprises one or more of La, Gd, Tb, and Lu, and wherein B’ comprises one or more of Ga, In, and Sc. Further, in such embodiments, the third luminescent material may comprise a secondary third luminescent material such as (Lux1A’x2Cex3)3(Aly1B’y2)5O12, wherein x1+x2+x3=1, wherein x1≥0.5, wherein A’ comprises one or more of Y, La, Gd, and Tb, and wherein B’ comprises one or more of Ga, In, and Sc. In embodiments, the primary third luminescent material may thus comprise on a molar basis more Y than Lu. Conversely, the secondary third luminescent material may comprise on a molar basis more Lu than Y. Especially, the primary third luminescent material may comprise on a molar basis more Y than the secondary third luminescent material, and the secondary third luminescent material may comprise on a molar basis more Lu than the primary third luminescent material. Note that in embodiments, x2 = 0, and the primary third luminescent material may (essentially) consist of (Yx1Cex3)3(Aly1B’y2)5O12, wherein x1+x3 = 1. Similarly, the secondary third luminescent material may (essentially) consist of (Lux1Cex3)3(Aly1B’y2)5O12, wherein x1+x3 = 1. Hence, in specific embodiments, the third luminescent material may comprise at least two luminescent materials of the type A3B5O12:Ce3+, wherein: (a) a primary third luminescent material of this type may comprise on a molar basis more Y than Lu, and (b) a secondary third luminescent material of this type
2023PF80227 21 may comprise on a molar basis more Lu than Y. Such a composition of third luminescent material may provide a broader spectral power distribution of the third luminescent material light. For instance, the primary third luminescent material may be configured to provide primary third luminescent material light, and the secondary third luminescent material may be configured to provide secondary third luminescent material light, wherein a centroid wavelength of the primary third luminescent material light may be larger than a centroid wavelength of the secondary third luminescent material light. Returning to the general embodiments of the third luminescent material, the luminescent material may comprise a luminescent material of the type A3Si6N11:Ce3+, wherein A comprises one or more of Y, La, Gd, Tb and Lu, such as in embodiments one or more of La and Y. In embodiments, the luminescent material may alternatively or additionally comprise one or more of MS:Eu2+ and/or M 2+ 2+ 2Si5N8:Eu and/or MAlSiN3:Eu and/or Ca2AlSi3O2N5:Eu2+, etc., wherein M comprises one or more of Ba, Sr and Ca, especially in embodiments at least Sr. Hence, in embodiments, the luminescent material may comprise one or more materials selected from the group consisting of (Ba,Sr,Ca)S:Eu, (Ba,Sr,Ca)AlSiN3:Eu and (Ba,Sr,Ca)2Si5N8:Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation; its presence will especially be in the range of about 0.5 to 10%, more especially in the range of about 0.5 to 5% relative to the cation(s) it replaces. The term “:Eu”, indicates that part of the metal ions is replaced by Eu (in these examples by Eu2+). For instance, assuming 2% Eu in CaAlSiN3:Eu, the correct formula could be (Ca0.98Eu0.02)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba. The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Further, the material (Ba,Sr,Ca)2Si5N8:Eu can also be indicated as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and/or Ba. In a further specific embodiment, M consists of Sr and/or Ba (not taking into account the presence of Eu), especially 50 to 100%, more especially 50 to 90% Ba and 50 to 0%, especially 50 to 10% Sr, such as Ba1.5Sr0.5Si5N8:Eu (i.e.75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca). Likewise, the
2023PF80227 22 material (Ba,Sr,Ca)AlSiN3:Eu can also be indicated as MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Eu in the above indicated luminescent materials is substantially or only in the divalent state, as is known to the person skilled in the art. The term “luminescent material” herein especially relates to inorganic luminescent materials. Alternatively or additionally, also other luminescent materials may be applied. For instance quantum dots and/or organic dyes may be applied and may optionally be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc. Especially, the third luminescent material may at least comprise one or more luminescent materials of the type A B O : 3+ 3 5 12 Ce . Further, in the embodiment the third luminescent material may (additionally) comprise one or more divalent europium comprising oxynitride luminescent materials and/or one or more divalent europium comprising nitride luminescent materials. In embodiments, the luminescent material (e.g. the first luminescent material and/or the second luminescent material) may comprise a luminescent material of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x may be selected from the range of 0-1, wherein A comprises a tetravalent cation, for instance comprising one or more of silicon and titanium, wherein X comprises a monovalent anion, at least comprising fluorine. Such luminescent materials may herein also be indicated as “KSiF” or “KSF”, whether or not M comprises K or one or more other alkaline cations. A luminescent material of the type M’xM2-2xAX6 doped with tetravalent manganese is amongst others described in WO2013121355A1, which is herein incorporated by reference. Passages from WO2013121355A1 are also copied herein. Herein, M’xM2-2xAX6 doped with tetravalent manganese, may further also shortly be indicated as “phosphor”, i.e. the phrase "phosphor comprising M’xM2-2xAX6 doped with tetravalent manganese" may in an embodiment also be read as M’xM2-2xAX6 doped with tetravalent manganese phosphor, or (tetravalent) Mn-doped M’xM2-2xAX6 phosphor, or shortly "phosphor". Relevant alkaline earth cations (M’) are magnesium (Mg), strontium (Sr), calcium (Ca) and barium (Ba), especially one or more of Sr and Ba. Relevant alkaline cations (M) are sodium (Na), potassium (K) and rubidium (Rb). Optionally, also lithium (Li) and/or cesium (Cs) may be applied. In a preferred embodiment, M comprises at least potassium. In yet another embodiment, M comprises at least rubidium. The phrase “wherein M comprises
2023PF80227 23 at least potassium” indicates for instance that of all M cations in a mole M’xM2-2xAX6 , a fraction comprises K+ and an optionally remaining fraction comprises one or more other monovalent (alkaline) cations (see also below). In another preferred embodiment, M comprises at least potassium and rubidium. Optionally, the M’xM2-2xAX6 luminescent material has the hexagonal phase. In yet another embodiment, the M’xM2-2xAX6 luminescent material has the cubic phase. In an embodiment, a combination of different alkaline cations may be applied. In yet another embodiment, a combination of different alkaline earth cations may be applied. In yet another embodiment, a combination of one or more alkaline cations and one or more alkaline earth cations may be applied. For instance, KRb0.5Sr0.25AX6 might be applied. As indicated above, x may be selected from the range of 0-1, especially x ≤ 1. In specific embodiments, x = 0. The term “tetravalent manganese” refers to Mn4+. This is a well-known luminescent ion. In the formula as indicated above, part of the tetravalent cation A (such as Si) is being replaced by manganese. Hence, M’xM2-2xAX6 doped with tetravalent manganese may also be indicated as M’xM2-2xA1-mMnmX6. The mole percentage of manganese, i.e. the percentage it replaces the tetravalent cation A will in general be in the range of 0.1-15 %, especially 1-12 %, i.e. m is in the range of 0.001-0.15, especially in the range of 0.01-0.12. A comprises a tetravalent cation, and preferably at least comprises silicon. A may optionally (further) comprise one or more of titanium (Ti), germanium (Ge), stannum (Sn) and zinc (Zn). Preferably, at least 80%, even more preferably at least 90%, such as at least 95% of M consists of silicon. Hence, in a specific embodiment, M’xM2-2xAX6 may also be described as M’xM2-2xA1-m-t-g-s-zrMnmTitGegSnsZrzrX6, wherein m and x are as indicated above, and wherein t,g,s,zr are each individually preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05, wherein t+g+s+zr is smaller than 1, especially equal to or smaller than 0.2, preferably in the range of 0-0.2, especially 0-0.1, even more especially 0- 0.05, and wherein A is especially Si. X is preferably fluorine (F). As indicated above, M relates to monovalent cations, but preferably at least comprises potassium and/or rubidium. Other monovalent cations that may further be comprised by M can be selected from the group consisting of lithium (Li), sodium (Na), cesium (Cs) and ammonium (NH + 4 ). In an embodiment, preferably at least 80%(i.e.80% of all moles of the type M), even more preferably at least 90%, such as 95% of M consists of potassium and/or rubidium. Especially, in these embodiments, x is thus zero. Hence, in a specific embodiment, M’xM2-2xAX6 can also be described as (K1-r-l- n-c-nh RbrLilNanCsc(NH4)nh)2AX6, wherein r is in the range of 0-1, wherein l,n,c,nh are each
2023PF80227 24 individually preferably in the range of 0-1, preferably 0-0.2, especially 0-0.1, even more especially 0-0.05, and wherein r+ l+n+c+nh is in the range of 0-1, especially l+n+c+nh is smaller than 1, especially equal to or smaller than 0.2, preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05. X is preferably fluorine (F). Specifically, A comprises one or more elements selected from the group of Si, Ti, Ge, Sn, and Zr, Further, specifically, M’ comprises one or more elements selected from the group Li, Na, K, Rb and Cs. As indicated above, instead of or in addition to the alkaline cation(s), also one or more alkaline earth cations may be present. Hence, in a specific embodiment, M’xM2- 2xAX6 can also be described as MgmgCacaSrsrBaba(KkRbrLilNanCsc(NH4)nh)2AX6, with k, r, l, n, c, nh each individually being in the range of 0-1, wherein mg, ca, sr, ba are each individually in the range of 0-1, and wherein mg+ca+sr+ba+k+ r+ l+n+c+nh=1. In embodiments, k=1, and the others (mg, ca, sr, ba, r, l, n, c, nh) are zero. As indicated above, X relates to a monovalent anion, but at least comprises fluorine. Other monovalent anions that may optionally be present may be selected from the group consisting of chlorine (Cl), bromine (Br), and iodine (I). Preferably, at least 80%, even more preferably at least 90%, such as 95% of X consists of fluorine. Hence, in a specific embodiment, M’xM2-2xAX6 can also be described as M’xM2-2xA(F1-cl-b-iClclBrbIi)6, wherein cl,b,i are each individually preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05, and wherein cl+b+i is smaller than 1, especially equal to or smaller than 0.2, preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05. Especially, X essentially consists of F (fluorine). Hence, M’xM2-2xAX6 can also be described as (K1-r-l-n-c-nh RbrLilNanCsc(NH4)nh)2Si1-m-t-g-s-zrMnmTitGegSnsZrzr(F1-cl-b-iClclBrbIi)6, with the values for r,l,n,c,nh,m,t,g,s,zr,cl,b,i as indicated above. X is preferably fluorine (F). Specifically, A comprises one or more elements selected from the group of Si, Ti, Ge, Sn, and Zr, Further, specifically, M’ comprises one or more elements selected from the group Li, Na, K, Rb and Cs. Even more especially, M’xM2-2xAX6 can also be described as MgmgCacaSrsrBaba(KkRbrLilNanCsc(NH4)nh)2Si1-m-t-g-s-zrMnmTitGegSnsZrzr(F1-cl-b-iClclBrbIi)6, with k, r, l, n, c, nh each individually being in the range of 0-1, wherein mg, ca, sr, ba are each individually in the range of 0-1, wherein mg+ca+sr+ba+k+ r+ l+n+c+nh=1, and with the values for m,t,g,s,zr,cl,b,i as indicated above. X is preferably fluorine (F). Specifically, A comprises one or more elements selected from the group of Si, Ti, Ge, Sn, and Zr, Further,
2023PF80227 25 specifically, M’ comprises one or more elements selected from the group Li, Na, K, Rb and Cs. In an embodiment, M’xM2-2xAX6 comprises K2SiF6 (indicated herein also as KSiF system). As indicated above, in another preferred embodiment, M’xM2-2xAX6 comprises KRbSiF6 (i.e. r=0.5 and l,n,c,nh,t,g,s,zr,cl,b,i are 0) (herein also indicated as K,Rb system). As indicated above, part of silicon is replaced by manganese (i.e. the formula may also be described as K2Si1-mMnmF6 or KRbSi1-mMnmF6, with m as indicated above, or as KRbSiF6:Mn and K2SiF6:Mn, respectively). As manganese replaces part of a host lattice ion and has a specific function, it is also indicated as “dopant” or “activator”. Hence, the hexafluorosilicate is doped or activated with manganese (Mn4+). Here below, M’xM2-2xAX6 is also indicated as M’xM’’2-2xAX6. In specific embodiments, the indication M’xM2-2xAX6 may refer to one or more of (K,Rb) SiF :Mn4+, (K,Rb) TiF :Mn4+, K (Si,Ti 4+ 2 6 2 6 2 )F6:Mn , Rb (Si,Ti)F :Mn4+, (K, Ge) (Si,Ti)F :Mn4+, such as one or more of K (Si,Ti) 4+ 2 6 2 6 2 F6:Mn Ge2(Si,Ti)F6:Mn4+, K2TiF6:Mn4+, K2SiF6:Mn4+, and Rb2TiF6:Mn4+. In embodiments, the second luminescent material may comprise (K,Rb)2TiF6:Mn4+. Further, in embodiments, the second luminescent material may comprise K2(Si,Ti)F6:Mn4+. In specific embodiments, the second luminescent material may especially comprise K2TiF6:Mn4+. As can be derived from the above, “Si,Ti” may indicate one or more of Si and Ti. In specific embodiments, MxM’2- 2xAaX6 comprises K2SiF4 and MxM’2-2xAbX6 comprises K2TiF4. The luminescent material may also be coated, as also described in WO2013121355A1. As indicated above, the first luminescent material may comprise a luminescent material of the type MxM’2-2xAaX6 doped with tetravalent manganese and the second luminescent material may comprise a luminescent material of the type MxM’2-2xAbX6 doped with tetravalent manganese. Here, M may comprise an alkaline earth cation, M’ may comprise an alkaline cation, x may be in the range of 0-1, Aa and Ab may comprise a tetravalent cation, and wherein X may comprise a monovalent anion, at least comprising fluorine, and Aa may comprise a higher molar percentage of Si than Ab. Specifically, Aa of the first luminescent material and Ab of the second luminescent material comprise one or more elements selected from the group of Si, Ti, Ge, Sn, and Zr, wherein Aa at least comprises Si and Ab at least comprises Ti. Further, specifically, M’ comprises one or more elements selected from the group Li, Na, K, Rb and Cs. Assume, for the sake of elucidating the molar percentages of Aa and Ab that the first luminescent material and the second luminescent material to be described as MxM’2- 2xSisxMnmTitGegSnsZrzrX6, wherein sx+m+t+g+zr=1. Further, as indicated above, m is in the
2023PF80227 26 range of 0.001-0.15. That is, the concentration of the tetravalent manganese dopant may be selected from the range of 0.1-15 % (relative to the total of tetravalent cation Aa or Ab). Note that the concentration of the tetravalent manganese dopant in the first luminescent material and the second luminescent material may in embodiments be relatively similar, essentially they may (even) be the same. Further, in general sx+t>0. Especially, in embodiments g, s, and zr are all 0. Further, in embodiments, x = 0, M’ = K, and X = F. In such specific embodiments, MxM’2-2xAaX6 and MxM’2-2xAbX6 may both be described as K2(Si,Ti,Mn)F4 or as K2SisxTitMnmF4. In embodiments, in the first luminescent material sx/(sx+t) is larger in the second luminescent material, such as 1 and 0, respectively, though 0.55 and 0.45, respectively, may also be chosen; however, also e.g.0.9 and 0.1, respectively, may be chosen. Further, in embodiments in the second luminescent material t/(sx+t) is larger in the second luminescent material, such as 1 and 0, respectively, though 0.55 and 0.45, respectively, may also be chosen; however, also e.g.0.9 and 0.1, respectively, may be chosen. Yet, in embodiments, sx>t for the first luminescent material and t>sx for the second luminescent material. Especially, in embodiments for the first luminescent material sx>0.5, and for the second luminescent material t>0.5. Yet, in specific embodiments sx+m=1 for the first luminescent material and t+m=1 for the second luminescent material. Hence, in embodiments, MxM’2-2xAaX6 may comprise K2SiF4 and MxM’2-2xAbX6 may comprise K2TiF4. Especially, the luminescent material may be comprised by the luminescent body. The luminescent body may be a layer, like a self-supporting layer. The luminescent body may also be a coating. The luminescent body may also comprise a luminescent coating on a support (especially a light transmissive support in the transmissive mode, or a reflective support in the reflective mode). Especially, the luminescent body may essentially be self- supporting. In embodiments, the luminescent body may comprise a light transmissive body, wherein the luminescent material is embedded. For instance, the luminescent body may comprise a glass body, with luminescent material embedded therein. Or, the glass as such may be luminescent. In other embodiments, the luminescent body may comprise a polymeric body, with luminescent material embedded therein. As mentioned above, it may be desired to control the spectral distribution of the system light. This may be facilitated by controlling the one or more different types of light generating devices. In embodiments, the n1 first light generating devices and/or the n2 second light generating devices may individually be controlled. Optionally, in embodiments, the one or more n3 third light generating devices may (also) be (individually) controlled. To
2023PF80227 27 facilitate control over the one or more aforementioned light generating devices the light generating system may in embodiments comprise a control system. Furthermore, in embodiments, the control system may be configured to control in dependence of an input signal of a user interface, a sensor signal (of a sensor), and a timer. In specific embodiments, the light generating system comprises a control system, wherein the control system is configured to individually control the n1 first light generating device, the n2 second light generating device, and the optional one or more third light generating device; wherein the control system is configured to 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 “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and/or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface. The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system. Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or
2023PF80227 28 “mode of operation” or “operational mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and/or after executing the mode one or more other modes may be executed. However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability). Hence, in embodiments, the control system may 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” may refer to a clock and/or a predetermined time scheme. As mentioned before, the light generating system may comprise one or more of the n1 first light generating devices, the n2 second light generating device and optionally one or more n3 third light generating devices. In specific embodiments, the light generating system comprises a LED filament, or a chip-on-board device. A LED filament may consist of multiple series-connected LEDs on a translucent (e.g. transparent) substrate (e.g. glass or sapphire materials). The translucent substrate may in embodiments facilitate an even and/or uniform dispersion of the light source light (in all directions). In embodiments, the LEDs may be placed on one or more sides of said substrate, such as on two (opposite) sides. Further, the LED filament may comprise an even coating comprising a luminescent body (optionally in a (silicon) binder). Further, a LED filament may comprise an array of a plurality of light sources (such as LEDs) arranged on (a first major surface of) an elongated carrier, wherein an (elongated) encapsulant is covering the plurality of LEDs and at least part of (said first major surface of) said elongated carrier, wherein the encapsulant may comprise the luminescent body. Especially, in embodiments, the luminescent body may be configured as an elongated encapsulant covering the plurality of light sources (i.e. LEDs) and at least part of the elongated carrier. In embodiments, the LED filament may (further) comprise an array of a plurality of light sources (such as LEDs) arranged on a second major surface of an elongated carrier, wherein an encapsulant is covering the plurality of LEDs and at least part of said second major surface of said elongated carrier. Hence, a LED filament may comprise an array of a plurality of light sources (such as LEDs) arranged on a first and second major surface of an elongated carrier.
2023PF80227 29 Hence, the LED filament may comprise a plurality of light sources. Further, the LED filament may comprise the luminescent body. Especially, the luminescent body may be configured surrounding the plurality of light sources. Hence, in specific embodiments, the light generating system may comprise a LED filament, wherein the LED filament may comprise (i) a plurality of light sources and (ii) the luminescent body, wherein the luminescent body may be configured surrounding the plurality of light sources. Further, in specific embodiments, the light generating system may comprise a LED filament, wherein the LED filament may comprise (i) a plurality of light sources arranged on an elongated carrier and (ii) the luminescent body, wherein the luminescent body may be configured as an elongated encapsulant covering the plurality of light sources and at least part of the elongated carrier. In embodiments, the elongated carrier may comprise a first face and a second face parallel to an axis of elongation of the elongated carrier, wherein the plurality of light sources may be arranged on at least the first face. Further, in embodiments, the LED filament may comprise a second encapsulant, wherein the second encapsulant may be configured covering at least part of the second face, and wherein the second encapsulant may comprise one or more of the luminescent body, the first luminescent material (particles), and the second luminescent material (particles). Yet, in embodiments, the elongated encapsulant (such as the luminescent body) may be configured (at least partially) covering the first face and the second face. In further embodiments, the plurality of light sources may be arranged on the first face and the second face, wherein both sides may be at least partially covered by the luminescent body. Such a LED filament may for instance be used in decorative light bulbs, to simulate the filaments of incandescent light bulbs. The term “COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of light emitting semiconductor light source may be configured on the same substrate. In embodiments, a COB is a multi LED chip configured together as a single lighting module. The luminescent body may be configured directly downstream from the of light emitting semiconductor light sources. In specific embodiments, the luminescent body may be in physical contact with the of light emitting semiconductor light sources. For instance, the luminescent arrangement may be provided as coating layer over the light emitting semiconductor light sources. In embodiments, the light generating system may be a LED filament. In other embodiments, the light generating system may be COB. Here below, some further embodiments are described.
2023PF80227 30 The term “light generating device” may also refer to a plurality of light generating devices which may provide device light having essentially the same spectral power distributions. In (other) specific embodiments, the term “light generating device” may also refer to a plurality of light generating devices which may provide device light having different spectral power distributions. The term “light source” may especially refer to an LED (light emissive diode). In a specific embodiment, the light source comprises a solid state LED light source (such as an LED or laser diode (or “diode laser”)). The term “light source” may also relate to a plurality of light sources, such as 2-2000 (solid state) LED light sources. Hence, the term LED may also refer to a plurality of LEDs. Further, the term “light source” may in embodiments also refer to a so-called chip-on-board (COB) light source. The term “light source” may also refer to a chip scaled package (CSP). A CSP may comprise a single solid state die with provided thereon a luminescent material comprising layer. The term “light source” may also refer to a midpower package. A midpower package may comprise one or more solid state die(s). The die(s) may be covered by a luminescent material comprising layer. The die dimensions may be equal to or smaller than 2 mm, such as in the range of e.g.0.2-2 mm. Hence, in embodiments the light source comprises a solid state light source. Further, in specific embodiments, the light source comprises a chip scale packaged LED. Herein, the term “light source” may also especially refer to a small solid state light source, such as having a mini size or micro size. For instance, the light sources may comprise one or more of mini LEDs and micro LEDs. Especially, in embodiment the light sources comprise micro LEDs or “microLEDs” or “µLEDs”. Herein, the term mini size or mini LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 µm – 1 mm. Herein, the term µ size or micro LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 µm and smaller. Further, the term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a laser diode, a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser (EEL), a photonic crystal surface emitting laser (PCSEL), a vertical external cavity surface emitting laser (VECSEL), etc... The term “light source” may also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid-state light source (such as an LED or laser diode). In an embodiment, the light source comprises an LED (light emitting diode).
2023PF80227 31 The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED). The term LED may also refer to a plurality of LEDs. The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2- 2000 solid state light sources. Hence, herein (in embodiments) the term “solid state light source” and “light source” may essentially be equivalent. In embodiments, the light source may be configured to provide primary radiation, which is used as such, such as e.g. a blue light source, like a blue LED, or a green light source, such as a green LED, and a red light source, such as a red LED. Such LEDs, which may not comprise a luminescent material (“phosphor”) may be indicated as direct color LEDs. In other embodiments, however, the light source may be configured to provide primary radiation and part of the primary radiation may be converted into secondary radiation. Secondary radiation may be based on conversion by a luminescent material. The secondary radiation may therefore also be indicated as luminescent material radiation. The luminescent material may in embodiments be comprised by the light source, such as an LED with a luminescent material layer or dome comprising luminescent material. Such LEDs may be indicated as phosphor converted LEDs or PC LEDs (phosphor converted LEDs). In other embodiments, the luminescent material may be configured at some distance (“remote”) from the light source, such as an LED with a luminescent material layer not in physical contact with a die of the LED. In other embodiments, the light generating device may comprise a direct LED (i.e. no phosphor). In embodiments, the light generating device may comprise a laser device, like a laser diode. In embodiments, the light generating device may comprise a superluminescent diode. Hence, in specific embodiments, the light source may be selected from the group of laser diodes and superluminescent diodes. In other embodiments, the light source may comprise an LED. The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from the same bin. The term “solid state light source”, or “solid state material light source”, and similar terms (like “light source”), may especially refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, or a superluminescent diode.
2023PF80227 32 Note that, the light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems. In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc... The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support one or more of the first light generating device(s), the second light generating device(s) and the luminescent arrangement. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: Fig.1 schematically depicts embodiments of the light generating system 1000;
2023PF80227 33 Fig.2A-2B depicts the absorption spectrum of the luminescent materials comprised by the light generating system 1000; Fig.3A-3C schematically depicts further embodiments of the light generating system 1000; and Fig.4 schematically depicts embodiments of the lighting device. The schematic drawings are not necessarily to scale. DETAILED DESCRIPTION OF THE EMBODIMENTS Fig.1 schematically depicts an embodiment of the light generating system 1000, especially configured to provide system light 1001. In embodiments, the system light 1001 may be white light having a correlated color temperature (CCT) selected from the range of 1500-6500 K, such as 1700-6500 K. Yet, in embodiments the system light 1001 may be white light having a correlated color temperature selected from the range of 1500-3000 K, such as 1700-2700 K. Furthermore, the system light 1001 may have a color rendering index (CRI) of at least 75, such as at least 80, especially at least 90. Here below, the configuration of the light generating 1000 to provide such system light 1001 is described. In embodiments, the light generating system 1000 may comprise n1 first light generating devices 110, n2 second light generating devices 120, and a luminescent arrangement 2000. In the embodiment depicted, the light generating system 1000 comprises two first light generating devices 110 and two second light generating devices 120. In further embodiments, n1 may be at least 1, such as at least 2, especially at least 5. Analogously, in further embodiments, n2 may be at least 1, such as at least 2, especially at least 5. Further, in the embodiment depicted, the luminescent arrangement 2000 is configured encapsulating the first light generating devices 110 and the second light generating devices 120. Especially, the luminescent arrangement 2000 may comprise a luminescent body further comprising a matrix material 2100 and one or more luminescent materials 210,220,230. Essentially, the luminescent body may be in physical contact with the one or more light generating devices 110,120. For example, the luminescent arrangement may be provided as a coating layer over the light generating devices 110,120. In embodiments, the n1 first light generating devices 110 may comprise one or more first solid state light sources 10. Especially, the n1 first light generating devices 110 may be configured to generate first device light 111 having a first centroid wavelength (λc1). The first centroid wavelength (λc1) may be selected from the wavelength range of 400-540 nm such as from the wavelength range of 425-443 nm, especially from the wavelength range
2023PF80227 34 of 430-440 nm. Analogously, the n2 second light generating devices 120 may comprise one or more second solid state light sources 20. Especially, the n2 second light generating devices 120 may be configured to generate second device light 121 having a second centroid wavelength (λc2). The second centroid wavelength (λc2) may be selected from the wavelength range of 400-540 nm, such as from the wavelength range of 465-525 nm, especially from the wavelength range of 500-525 nm, more especially from the wavelength range of 500-510 nm. In embodiments, the luminescent arrangement 2000 may comprise a first luminescent material 210 and a second luminescent material 220. Especially, the first luminescent material 210 may be configured to convert at least part of the first device light 111 and/or at least part of the second device light 121 received by the first luminescent material 210 into first luminescent material light 211. In a similar vein, the second luminescent material 220 may especially be configured to convert at least part of the first device light 111 and/or at least part of the second device light 121 received by the second luminescent material 220 into second luminescent material light 221. The system light 1001 may especially comprise first luminescent material light 211 and the second luminescent material light 221. In the embodiment depicted, the luminescent arrangement 2000 comprises a matrix material 2100, the first luminescent material 210 and the second luminescent material 220. Further, the luminescent arrangement 2000 comprises first luminescent material particles comprising the first luminescent material 210. Furthermore, the luminescent arrangement 2000 comprises second luminescent particles comprising the second luminescent material 220. The first luminescent material particles and the second luminescent material particles may be embedded in the matrix material 2100. The first luminescent material 210 may comprise a luminescent material of the type MxM’2-2xAaX6 doped with tetravalent manganese. The second luminescent material 220 may comprise a luminescent material of the type MxM’2-2xAbX6 doped with tetravalent manganese. Here, M comprises an alkaline earth cation, M’ comprises an alkaline cation, x is in the range of 0-1, Aa and Ab comprise a tetravalent cation, and X comprises a monovalent anion, at least comprising fluorine, and Aa comprises a higher molar percentage of Si than Ab, and Ab comprises a higher molar percentage of Ti than Aa. In embodiments, the first centroid wavelength (λc1) may be selected such that an absorption by the first luminescent material 210 at this first centroid wavelength (λc1) is at least as high as an absorption by the second luminescent material 220 (at this first centroid wavelength (λc1)), and the second centroid wavelength (λc2) is selected such that an absorption by the second luminescent material 220 at this second centroid wavelength (λc2) is
2023PF80227 35 relatively higher than an absorption by the first luminescent material 210 (at this second centroid wavelength (λc2)). See e.g. also Fig.2A & 2B. In embodiments, the percentage of the first luminescent material light 211 relative to the percentage of the second luminescent material light 221 in the outcoupled system light 1001 may be (individually) controlled in dependence of the weight percentage of the first luminescent material 210 relative to the second luminescent material 220. Hence, the luminescent arrangement 2000 may comprise a composition comprising the first luminescent material 210 with a first weight percentage C1 relative to the composition and the second luminescent material 220 with a second weight percentage C2 relative to the composition. Therefore, in embodiments, 0.5≤C1/C2≤2. Note that the luminescent arrangement 2000 comprises a combination of both the first luminescent material 210 and the second luminescent material 220. Especially, C1+C2 ≥ 10%, such as C1+C2 ≥ 15%, especially C1+C2 ≥ 20%. Furthermore, C1+C2≤100%, such as C1+C2≤90%, especially C1+C2≤80%. Furthermore, in some embodiments, the second luminescent material may have a relatively higher absorption in the blue-green wavelength range compared to the first luminescent material. Hence, to compensate for this, the first weight percentage C1 may be selected to larger than the second weight percentage C2. Especially, 1<C1/C2≤2. In embodiments, the light generating system 1000 may comprise n1 first light generating devices 110 and n2 second light generating devices 120. In the depicted embodiment, there are an equal number of first light generating devices 110 and second light generating devices 120 (i.e., n1=n2=2). In further embodiments, the ratio of the (generated) first device light 111 relative to the (generated) second device light 121 may be varied by varying n1 relative to n2. Especially, n1 and n2 may be selected such that 0.5≤n1/n2≤2. Further, to compensate for the relatively higher absorption in the blue-green wavelength range by the second luminescent material 220 compared to the first luminescent material 210 n1 may be selected to be larger than n2. Especially, 1<n1/n2≤2. White light may be provided by combining unconverted (or non-converted) device light 111,121 (e.g. in the blue-green wavelength range) with converted luminescent material light 211,221 (e.g. in the orange-red wavelength range). Especially, the luminescent arrangement 2000 may be configured such that (i) selected from the range of 10-90% of the first device light 111 is not converted and selected from the range of 10-90% of the second device light 121 is not converted. For instance, assuming a transmissive mode, the centroid wavelengths of the first light generating devices 110 and second light generating devices 120
2023PF80227 36 may be selected such that part of the respective device light 111,121 is converted and part of the respective device light 111,121 is transmitted (and may end up in the system light 1001). In further embodiments, the light generating system 1000 may comprise a third luminescent material 230. In the embodiment depicted, the luminescent arrangement 2000 comprises third luminescent material particles further comprising the third luminescent material 230. Especially, the third luminescent material 230 may comprise a luminescent material of the type A3B5O12:Ce3+, where A comprises one or more of Y, La, Gd, Tb and Lu, and B comprises one or more of Al, Ga, In and Sc. The third luminescent material may convert the first device light 111 and/or the second device light 121 to third luminescent material light 231. The additional third luminescent material light 231 may facilitate controlling one or more of the spectral distribution, CCT and CRI of the system light 1001. The third luminescent material 230 may in specific embodiments comprise two or more different types of third luminescent material. In a further embodiment, the third luminescent material 230 may comprise a primary third luminescent material of the type (Yx11Lux12A’x13Cex14)3B5O12 and a secondary third luminescent material of the type (Yx21Lux22A’x23Cex24)3B5O12, where A’ comprises one or more of La, Gd, and Tb, B comprises one or more of Al, Ga, In and Sc, and x11+x12+x13+ x14=1; x11+x12>0, 0≤x13<1, and 0.001≤x14≤0.1. Further, in embodiments, x21+x22+x23+ x24=1, x21+x22>0, 0≤x23<1, and 0.001≤x24≤0.1. Especially, x11>x21 meaning there may be relatively more Y in the primary third luminescent material as compared to the secondary third luminescent material. Further, in embodiments, x22>x12 meaning there may be more Lu in the secondary third luminescent material as compared to the primary third luminescent material. In the depicted embodiment, the light generating system 1000 further comprises a control system 300 to facilitate controlling the n1 first light generating devices 110 and the n2 second light generating devices 120. Especially, the control system 300 may be configured to individually control the n1 first light generating device 110, the n2 second light generating device 120, and the optional one or more third light generating device 130. In further embodiments, the control system 300 may be configured to 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 CCT, the CRI, and the spectral distribution of the system light 1001 may be controlled. In a further aspect, the invention may provide a lighting device 1200 comprising the light generating system 1000. Note that, in embodiments, the light generating system 1000 may comprise a LED filament 420 (see e.g. Fig.3C), or a chip-on-board (COB) device.
2023PF80227 37 Fig.2A depicts the absorption spectrum of the luminescent materials comprised by the light generating system 1000. As mentioned above, the light generating system 1000 may comprise a first luminescent material 210 and a second luminescent material 220. In the figure, the first luminescent material 210 comprises K2SiF4 (KSF) and the second luminescent material 220 comprises K2TiF4 (KTF). From the figure, it can be observed that K2TiF4 has a relatively higher absorption peak in the blue-green wavelength range as compared to K2SiF4. Further, the first centroid wavelength (λc1) may be selected such that an absorption by K2SiF4 at this first centroid wavelength (λc1) is at least as high as an absorption by K2TiF4 (at this first centroid wavelength (λc1)), and the second centroid wavelength (λc2) may be selected such that an absorption by the K2TiF4 at this second centroid wavelength (λc2) is relatively higher than an absorption by K2SiF4 (at this second centroid wavelength (λc2)). Furthermore, the use of two different types of light generating devices (i.e., the first light generating device 111 and the second light generating device 121) configured to generate light at two different centroid wavelengths λc1 and λc2 provides the advantage of controlling the percentage of light in the blue-wavelength range (comprised by the system light 1001). Hence, the CCT may especially be controlled. Therefore, λc1 and λc2 may be selected such that |λc2-λc1|≥10 nm, such as |λc2-λc1|≥15 nm, especially |λc2-λc1|≥20 nm, more especially |λc2-λc1|≥25 nm. Note that in Fig.2a the spectra have not been normalized to the peak (maximum) of the respective 4A2-4T2 transition, which is at about 445 nm for KSF and at about 475 for KTF. Fig.2B depicts the distribution of the intensity of the first device light 111 and the second device light 121. Here, the first centroid wavelength (λc1) may especially be selected from the wavelength range of 425-443 nm. Furthermore, the second centroid wavelength (λc2) may be selected from the wavelength range of 465-525 nm, such as from the wavelength range of 500-525 nm, more especially from the wavelength range of 500-510 nm. By controlling the radiant fluxes of the first light generating devices 111 and the second light generating devices 121, droop (of effectively (at least part of) the system light) may be reduced, delayed, or even essentially prevented. Fig.3A depicts an embodiment of the light generating device 1000. The embodiment depicted in the figure is analogous to the embodiment depicted in Fig.1. Hence, for the sake of brevity a description of some of the features is not repeated. In the depicted embodiment, the light generating system 1000 comprises third light generating devices 130 (further comprising third light source 30). Especially, the third
2023PF80227 38 light generating device 130 may generate third device light 131. Further, in the depicted embodiment, the light generating system 1000 comprises the first luminescent material 210, the second luminescent material 220 and the third luminescent material 230. The general term “device light” may be used to refer to the first device light 111, the second device light 121, and the third device light 131. The first luminescent material 210 may convert device light into first luminescent material light 211, the second luminescent material 220 may convert device light into the second luminescent material light 221, and the third luminescent material 230 may convert device light into third luminescent material light 231. In embodiments, the (outcoupled) system light 1001 may especially comprise non-converted first device light 111, non-converted second device light 121 and non-converted third device light 131. Additionally, in embodiments, the system light 1001 may comprise the first luminescent material light 211, the second luminescent material light 221, and the third luminescent material light 231. By mixing three different types of device light 111,121,131 and three different types of luminescent material light 211,221,231, the spectral distribution of the system light 1001 may especially be controlled. In embodiments, one or more of the following may apply: (I) at least part of the system light 1001 may comprise one or more of (i) non-converted first device light 111 and (ii) non-converted first device light 121, (II) the luminescent arrangement 2000 may comprise a third luminescent material 230 configured to convert at least part of one or more of (i) the first device light 111, (ii) the second device light 121, and (iii) light of a further light generating device into third luminescent material light 231 having a spectral power distribution different from the first luminescent material light 211 and the second luminescent material light 221; and (III) the light generating system 1000 may comprise one or more third light generating devices 130 configured to generate third device light 131. Fig.3B schematically depicts an embodiment of the light generating system 1000. In some embodiments, it may be desired to alter the spectral distribution of the system light 1001 by the addition of third device light 131. Especially, it may be desired to directly outcouple third device light 131 (without a subsequent conversion by the luminescent arrangement 2000). This may provide the advantage of mixing light of a desired color with (the remainder of) the system light 1001. Such a configuration may be facilitated by means of a dichroic filter 770. In the depicted embodiment, the dichroic filter 770 may reflect (a part of) the third device light 131 while it may transmit (a part of) the first luminescent material light 211 and the second luminescent material light 221. That is, the dichroic filter may be transmissive
2023PF80227 39 for light in the orange-red wavelength range and reflective for light in the blue-green wavelength range. Here, the dichroic filter 770 is configured downstream of the first light generating device 110, the second light generating device 120 and the luminescent arrangement 2000. Hence, only the first luminescent material light 211 and the second luminescent material light 221 comprising light in the orange-red wavelength range may be transmitted downstream via the dichroic filter 770 (and the first device light 111 and the second device light 121 comprising light in the blue-green wavelength range may be reflected upstream). To compensate for the missing light in the blue-green wavelength range, the third light generating device 130 may be configured away (and separate) from the dichroic filter 770. Here, the third device light 131 may be reflected by a reflector 770 (e.g. a mirror) onto the dichroic filter 770 and subsequently, the third device light 131 may be reflected further downstream by the dichroic filter 770. In this way, third device light 131 may be mixed with the remainder of the system light 1001. Furthermore, the light generating system 1000 may further comprise additional optical elements configured to beam shape the system light 1001 (e.g. a lens or a collimator). The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is “downstream”. In summary, in embodiments, the spectral distribution of the system light 1001 may be varied by the addition of the third device light 131. In further embodiments, the third light generating device 130 may be configured to generate third device light 131 having spectral power at one or more wavelengths selected from one or more of the blue wavelength range, the green wavelength range, the yellow wavelength range, the orange wavelength range, and the red wavelength range. Fig.3C schematically depicts a cross-section of a LED filament 420. In embodiments, the light generating system 1000 may comprise the LED filament 420. The LED filament 420 may especially comprise a plurality of first light generating devices 110 configured to generate the first device light 111. The first light generating device 110 may especially further comprise a first light source 10. Analogously, the LED filament 420 may especially comprise a plurality of second light generating devices 120 configured to generate
2023PF80227 40 second device light 121. The second light generating devices 120 may especially further comprise a second light source 20. In the depicted embodiment, the LED filament 420 may comprise an elongated support 425 further comprising two main faces 4251,4252. The light sources 10 are configured on the elongated support 425, at one of the main faces 4251,4252, or only one of these main faces 4251,4252 (here both faces are provided with the light sources 10,20). As depicted in the figure, the first light generating devices 110 and the second light generating devices 120 may be encapsulated by the luminescent arrangement 2000. With such an arrangement, the system light 1001 comprising the first device light 111, the second device light 121, the first luminescent material light 211 and the second luminescent material light 221, may be outcoupled. Fig.4 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. Fig.4 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000. Hence, Fig.4 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 as described herein. In embodiments, such lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments thus be system light 1001. The term “plurality” refers to two or more. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of”. The term “and/or”
2023PF80227 41 especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of" but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species". Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In yet a further aspect, the invention (thus) provides a
2023PF80227 42 software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein. The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system. The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.