Efficient low blue solution LED spectrum with sufficient cri

Abstract

The invention provides a light generating system (1000) comprising a first solid state light source (10), a first luminescent material (210), and a second luminescent material (220), wherein: (A) the first solid state light source (10) is configured to generate first light source light (11) having a peak wavelength selected from the 430-490 nm wavelength range; (B) the first luminescent material (210) is configured in a light receiving relationship with the first solid state light source (10) and is configured to convert at least part of the first light source light (11) into first luminescent material light (211); wherein the first luminescent material light (211) has a first spectral power distribution with a first emission band (EM1) having a first centroid wavelength (λc1) selected from the 530-600 nm wavelength range and a first full width half maximum (FWHM1) of at least 70 nm; (C) the second luminescent material (220) is (a) configured in a light receiving relationship with one or more of (ai) the first solid state light source (10) and (aii) the first luminescent material (210), and is (b) configured to convert one or more of (bi) at least part of the first light source light (11) and (bii) at least part of the first luminescent material light (211) into second luminescent material light (221); wherein the second luminescent material light (221) has a second spectral power distribution with a second emission band (EM2) having a second centroid wavelength (λc2) selected from the 605-660 nm wavelength range and a second full width half maximum (FWHM2) of at least 50 nm; and (D) the light generating system (1000) is configured to generate system light (1001), wherein: (a) the system light (1001) has a spectral power distribution comprising a system light emission band (EMS), wherein the system light emission band (EMS) comprises at least part of the first emission band (EM1) and at least part of the second emission band (EM2), (b) the spectral power distribution of the system light (1001) has in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm, and (c) the system light (1001) has a color rendering index of at least 60 and a correlated color temperature selected from the range of 1500-3000 K.

Description

[0001] Efficient low blue solution LED spectrum with sufficient CRI

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating system and to a lighting device comprising such light generating system.

[0004] BACKGROUND OF THE INVENTION

[0005] Lighting devices are known in the art. US2011273107, for instance, describes a light-emitting diode (LED)-based solid-state device comprising a color mixing mechanism to dynamically change the correlated color temperature (CCT) of a white light. With different lumen proportions for white phosphor-coated LEDs and integrated red and green LEDs, the light mixtures can be located in any one of eight CCT quadrangles. In practice, CCTs of a white-light can be tuned in a continuous manner. Because all the possible light mixtures on the chromaticity diagram correspond to a line segment that overlays the Planckian locus within the eight CCT tolerance quadrangles, the effect of LED intensity fluctuations that may put the mixture out of white light region is reduced.

[0006] EP4300606A1 discloses a light emitting device with a solid-state light emitting element emitting primary light, a first wavelength converter including a first phosphor, and a second wavelength converter including a second phosphor. The device emits output light. The first wavelength converter absorbs at least part of the primary light and converts this part of the primary light to first wavelength-converted light having a fluorescence peak in a visible wavelength range of 380 nm or more and less than 780 nm. The second wavelength converter absorbs at least part of first mixed light including first transmitted primary light, which is the primary light that has passed through the first wavelength converter, and the first wavelength-converted light, and converts the first mixed light to second wavelength-converted light having a fluorescence peak in a wavelength range of more than 700 nm and having a near-infrared component in a wavelength range of 780 nm or more and less than 2500 nm. The first mixed light is light of a light color with a correlated color temperature of 2500 K or more and less than 40,000 K.

[0007] US2022 / 199869A1 discloses a light emitting diode structure including a blue LED chip to produce a first light beam, a first light conversion layer disposed on the light emitting unit to convert a part of the first light beam into a second light beam, and a second light conversion layer disposed on the first light conversion layer to convert another part of the first light beam into a third light beam is provided. The remaining part of the first light beam, the second light beam, and the third light beam are superposed to form a working light beam whose spectrum includes a first wave band ranging from 350 nm to 660 nm and a second wave band ranging from 660 nm to 1000 nm.

[0008] WO2022 / 176782A1 discloses a light-emitting device provided with a solid- state light-emitting element and a fluorescent substance and emits output light. The spectral distribution of the output light includes a first light component and a second light component derived from fluorescent light emitted from the fluorescent substance, in which a first local minimal value appears between the first light component and the second light component. The first light component is a fluorescent component having a maximum intensity value in a wavelength range of 560 nm or longer and shorter than 700 nm. The second light component is a fluorescent component having a maximum intensity value in a wavelength range of 700 nm or longer and shorter than 2500 nm.

[0009] US2019 / 305192A1 discloses a light emitting device including a blue light emitting portion configured to emit blue light, a green light emitting portion configured to emit green light, and a red light emitting portion configured to emit red light, in which the blue light emitting portion includes a near-UV light emitting diode chip and a first wavelength conversion portion for wavelength conversion of near-UV light emitted from the near-UV light emitting diode chip, the blue light emitted from the blue light emitting portion includes a first peak wavelength in a wavelength band corresponding to near-UV light and a second peak wavelength in a wavelength band corresponding to blue light, and an intensity of the first peak wavelength is in a range of 0% to 20% of an intensity of the second peak wavelength.

[0010] SUMMARY OF THE INVENTION

[0011] For specific applications, like in some type of laboratories or industrial manufacturing or processing factories, or like in some outdoor applications, it appears desirable to have a low blue light intensity. However, on the other hand, it may be desirable to have lighting conditions that provide enough visibility, e.g. for safety reasons or for wellbeing. Further, it appears desirable to have relatively light efficient sources of light. Current sources of light may not comply with one or more of these aspects. 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.

[0012] According to a first aspect, the invention provides a light generating system (“system”) comprising a first light source, especially a first solid state light source, a first luminescent material, and a second luminescent material. In embodiments, the first (solid state) light source may be configured to generate first light source light having a peak wavelength selected from the 430-490 nm wavelength range. Especially, the first luminescent material may be configured in a light receiving relationship with the first (solid state) light source and may be configured to convert at least part of the first light source light into first luminescent material light. In specific embodiments, the first luminescent material light may have a first spectral power distribution with a first emission band (EMI) having a first centroid wavelength (Xci) selected from the 530-600 nm wavelength range. Further, in embodiments, the first spectral power distribution may have a first full width half maximum (FWHM1) of at least 70 nm. In embodiments, the second luminescent material may be configured in a light receiving relationship with one or more of (i) the first (solid state) light source and (ii) the first luminescent material. Further, the second luminescent material may be in embodiments be configured to convert one or more of (i) at least part of the first light source light and (ii) at least part of the first luminescent material light into second luminescent material light. Especially, in embodiments the second luminescent material light may have a second spectral power distribution with a second emission band (EM2) having a second centroid wavelength (X^) selected from the 605-660 nm wavelength range. Further, in embodiments the second emission band (EM2) may have and a second full width half maximum (FWHM2) of at least 40 nm, such as at least 50 nm. Especially, in embodiments the light generating system may be configured to generate system light. Especially, the system light may have a spectral power distribution comprising a system light emission band (EMS). In embodiments, the system light emission band (EMS) may comprise at least part of the first emission band (EMI) and at least part of the second emission band (EM2). In specific embodiments, the spectral power distribution of the system light may have in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm. Yet, in embodiments, the system light may have a color rendering index (CRI) of at least 60 and / or a correlated color temperature (CCT) selected from the range of 1500- 3000 K. Hence, in specific embodiments the invention provides a light generating system comprising a first solid state light source, a first luminescent material, and a second luminescent material, wherein: (A) the first solid state light source is configured to generate first light source light having a peak wavelength selected from the 430-490 nm wavelength range; (B) the first luminescent material is configured in a light receiving relationship with the first solid state light source and is configured to convert at least part of the first light source light into first luminescent material light; wherein the first luminescent material light has a first spectral power distribution with a first emission band (EMI) having a first centroid wavelength (Xci) selected from the 530-600 nm wavelength range and a first full width half maximum (FWHM1) of at least 70 nm; (C) the second luminescent material is (a) configured in a light receiving relationship with one or more of (ai) the first solid state light source and (aii) the first luminescent material, and is (b) configured to convert one or more of (bi) at least part of the first light source light and (bii) at least part of the first luminescent material light into second luminescent material light; wherein the second luminescent material light has a second spectral power distribution with a second emission band (EM2) having a second centroid wavelength (X^) selected from the 605-660 nm wavelength range and a second full width half maximum (FWHM2) of at least 50 nm; and (D) the light generating system is configured to generate system light, wherein: (a) the system light has a spectral power distribution comprising a system light emission band (EMS), wherein the system light emission band (EMS) comprises at least part of the first emission band (EMI) and at least part of the second emission band (EM2), (b) the spectral power distribution of the system light has in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm, and (c) the system light has a color rendering index of at least 60 and a correlated color temperature selected from the range of 1500-3000 K.

[0013] With the current invention relatively efficient solutions can be provided, fulfilling the requirement of low blue content. Further, solutions are possible with a CRI of at least 60, such as even at least 70. Further, the current invention may provide a relatively simple solution, with a limited number of components.

[0014] As indicated above, the light generating system may especially comprise a first solid state light source, a first luminescent material, and a second luminescent material. Embodiments therefor will be elucidated below.

[0015] The term “light source” may in principle relate to any light source known in the art. It may be a conventional (tungsten) light bulb, a low pressure mercury lamp, a high pressure mercury lamp, a fluorescent lamp, an LED (light emitting diode). In a specific embodiment, the light source comprises a solid state 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 “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.

[0016] 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 “pLEDs”. 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 pm - 1 mm. Herein, the term p 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 pm and smaller.

[0017] The light source may have a light escape surface. Referring to conventional light sources such as light bulbs or fluorescent lamps, it may be an outer surface of a glass or a quartz envelope. For LED’s it may for instance be the LED die, or when a resin is applied to the LED die, the outer surface of the resin. In principle, it may also be the terminal end of a fiber. The term escape surface especially relates to that part of the light source, where the light actually leaves or escapes from the light source. The light source is configured to provide a beam of light. This beam of light (thus) escapes from the light exit surface of the light source.

[0018] Likewise, a light generating device may comprise a light escape surface, such as an end window. Further, likewise a light generating system may comprise a light escape surface, such as an end window. The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term “light source” may also refer to an organic light-emitting diode (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). The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED).

[0019] The term LED may also refer to a plurality of LEDs.

[0020] 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. In embodiments, the light source may comprise one or more micro-optical elements (array of micro lenses) downstream of a single solid-state light source, such as an LED, or downstream of a plurality of solid-state light sources (i.e. e.g. shared by multiple LEDs). In embodiments, the light source may comprise an LED with on-chip optics. In embodiments, the light source comprises pixelated single LEDs (with or without optics) (offering in embodiments on-chip beam steering).

[0021] 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”.

[0022] 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.

[0023] In other embodiments, however, the light source may be configured to provide primary radiation and part of the primary radiation is 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. Hence, in specific embodiments the light source may be a light source that during operation emits at least light at wavelength selected from the range of 380-470 nm. However, other wavelengths may also be possible. This light may partially be converted by the luminescent material.

[0024] In embodiments, the light generating device may comprise a luminescent material. In embodiments, the light generating device may comprise a PC 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.

[0025] The light source may especially be configured to generate light source light having an optical axis (O), (a beam shape,) and a spectral power distribution. The light source light may in embodiments comprise one or more bands, having band widths as known for lasers.

[0026] The term “light source” may (thus) refer to a light generating element as such, like e.g. a solid state light source, or e.g. to a package of the light generating element, such as a solid state light source, and one or more of a luminescent material comprising element and (other) optics, like a lens, a collimator. A light converter element (“converter element” or “converter”) may comprise a luminescent material comprising element. For instance, a solid state light source as such, like a blue LED, is a light source. A combination of a solid state light source (as light generating element) and a light converter element, such as a blue LED and a light converter element, optically coupled to the solid state light source, may also be a light source (but may also be indicated as light generating device). Hence, a white LED is a light source (but may e.g. also be indicated as (white) light generating device). The term “light source” herein may also refer to a light source comprising a solid state light source, such as an LED or a laser diode or a superluminescent diode.

[0027] The term “light source” may (thus) in embodiments also refer to a light source that is (also) based on conversion of light, such as a light source in combination with a luminescent converter material. Hence, the term “light source” may also refer to a combination of an LED with a luminescent material configured to convert at least part of the LED radiation, or to a combination of a (diode) laser with a luminescent material configured to convert at least part of the (diode) laser radiation.

[0028] In embodiments, the term “light source” may also refer to a combination of a light source, like an LED, and an optical filter, which may change the spectral power distribution of the light generated by the light source. Especially, the term “light generating device” may be used to address a light source and further (optical components), like an optical filter and / or a beam shaping element, etc.

[0029] 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.

[0030] The term “solid state light source”, or “solid state material light source”, and similar terms, may especially refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, or a superluminescent diode. Herein, especially the term “solid state light source”, may refer to one or more light emitting diode (LED). The invention will further be explained in relation to a first solid state light source (such as a LED).

[0031] In embodiments, the first solid state light source may be configured to generate first light source light having a peak wavelength selected from the 430-490 nm wavelength range, more especially selected from the wavelength range of 440-490 nm, such as selected from the wavelength range of 440-460 nm. In specific embodiments, the first solid state light source may be configured to generate first light source light having a peak wavelength selected from the 445-455 nm wavelength range.

[0032] The term “luminescent material” especially refers 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 the 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 the so-called up-conversion.

[0033] 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 of a smaller wavelength is converted into radiation with a larger wavelength (Xex<Xem), though in specific embodiments the luminescent material may comprise up-converter luminescent material, i.e. radiation of a larger wavelength is converted into radiation with a smaller wavelength ( x> m).

[0034] 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 “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.

[0035] 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 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.

[0036] 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.

[0037] In specific embodiments the luminescent material comprises a luminescent material of the type AsBsOn Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, especially (at least) one or more of Y, Gd, Tb and Lu, and wherein B in embodiments 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 or lutetium and wherein B comprises at least aluminum. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B may comprise aluminum (Al); however, in addition to aluminum, B may also partly comprise gallium (Ga) and / or scandium (Sc) and / or 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 (Yi-xLux)3B50i2:Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1. The term “:Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the “A” ions) in the luminescent material is replaced by Ce. For instance, in the case of (Yi-xLux)3A150i2:Ce, part of Y and / or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will replace A in general for not more than 10%; in general, the Ce concentration will be in the range of 0.1 to 4%, especially 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the full correct formula could be (Yo.iLuo.89Ceo.oi)3A150i2. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art.

[0038] In embodiments, the luminescent material (thus) comprises A3B5O12 wherein in specific embodiments at maximum 10% of B-0 may be replaced by Si-N.

[0039] In specific embodiments the luminescent material comprises (YxiA’X2CeX3)3(AlyiB’y2)5Oi2, wherein xl+x2+x3=l, wherein x3>0, wherein 0<x2+x3<0.2, wherein yl+y2=l, wherein especially 0<y2<0.2, wherein A’ comprises one or more elements selected from the group consisting of lanthanides, and wherein B’ comprises one or more elements selected from the group consisting of Ga, In and Sc. In embodiments, x3 is selected from the range of 0.001-0.1. In the present invention, especially xl>0, such as >0.2, like at least 0.8. Garnets with Y may provide suitable spectral power distributions.

[0040] In specific embodiments at maximum 10% of B-0 may be replaced by Si-N. Here, B in B-0 refers to one or more of Al, Ga, In and Sc (and O refers to oxygen); in specific embodiments B-0 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 (Yxi(Lu,Gd)x2Cex3)3(AlyiGay2)5Oi2, 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-0 may be replaced by Si-

[0041] 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 (YxiCexs^ALOn, wherein xl+x3=l, and wherein 0<x3<0.2, such as 0.001-0.1.

[0042] In specific embodiments, the light generating device may include luminescent materials selected from the type of cerium comprising garnets. In even further specific embodiments, the light generating device includes a single type of luminescent materials, such as (YxiA’x2Cex3)3(AlyiB’y2)5Oi2. Hence, in specific embodiments the light generating device comprises 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 (YxiA’x2Cex3)3(AlyiB’y2)5Oi2. Here, wherein A’ comprises one or more elements selected from the group consisting of lanthanides, and wherein B’ comprises one or more elements selected from the group consisting of Ga, In and Sc, wherein xl+x2+x3=l, wherein x3>0, wherein 0<x2+x3<0.2, wherein yl+y2=l, 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.

[0043] In specific embodiments, A may especially comprise at least Y, and B may especially comprise at least Al.

[0044] Alternatively or additionally, the luminescent material may comprise a luminescent material of the type AsSieNiuCe3, wherein A comprises one or more of Y, La, Gd, Tb and Lu, such as in embodiments one or more of La and Y.

[0045] In embodiments, the luminescent material may alternatively or additionally comprise one or more of MS:Eu2+and / or IVhSisNs Eu2and / or MAlSiNrEu2and / or Ca2AlSi3O2Ns:Eu2+, etc., wherein M comprises one or more of Ba, Sr and Ca, especially in embodiments at least Sr. Hence, in embodiments, the luminescent 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)2SisN8: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

[0046] O.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 CaAlSi Eu, the correct formula could be (Cao.98Euo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba. The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Further, the material (Ba,Sr,Ca)2SisN8:Eu can also be indicated as NfcSis 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 Bai.sSro.sSisNsHu (i.e. 75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca). Likewise, the material (Ba,Sr,Ca)AlSiN3:Eu can also be indicated as MAlSi 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.

[0047] In embodiments, a red luminescent material may comprise one or more materials selected from the group consisting of (Ba,Sr,Ca)S:Eu, (Ba,Sr,Ca)AlSiN3:Eu and (Ba,Sr,Ca)2SisN8: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 CaAlSi Eu, the correct formula could be (Cao.98Euo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba.

[0048] 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).

[0049] Further, the material (Ba,Sr,Ca)2SisN8:Eu can also be indicated as NfcSis 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 Bai.sSro.sSisNsHu (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).

[0050] Likewise, the material (Ba,Sr,Ca)AlSiN3:Eu can also be indicated as MAlSi 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).

[0051] In embodiments, the luminescent material may comprise a luminescent material of the type Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux. Herein, M may comprise one or more of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), such as especially one or more of Ca, Sr, and Ba. Hence, Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Euxmay especially refer to (Mg,Ca,Sr,Ba)i-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux. Such a luminescent material may be indicated as an SLA-type phosphor, or SLA phosphor. Luminescent materials of the type Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux may be described in US2021171827A1, which is hereby herein incorporated by reference. In Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux, x may be selected from the range of 0 < x < 0.1, such as from the range of 0.0005 < x < 0.08, especially from the range of 0.001 < x < 0.05. Hence, europium (Eu) may not replace more than 10% of the cation M, and may substantially or only be in the divalent state (Eu2+), as is known to the person skilled in the art. Further, in Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux, y may be selected from the range of 0 < y < 1, such as from the range of 0 < y < 0.75, especially from the range of 0 < y < 0.6. In specific embodiments, y = 0. In Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux, z may be selected from the range of 0 < z < 0.1, such as from the range of 0 < z < 0.07, especially from the range of 0 < z < 0.05. Hence, in embodiments, in an SLA phosphor, SiN may replace A1O to a maximum of 10 mole%. In embodiments, an SLA phosphor may crystallize in a UCr4C4 type crystal structure. Hence, the luminescent material may comprise a luminescent material of the type Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z:Eux, wherein M comprises one or more of Ca, Sr, and Ba, wherein 0 < x < 0.04, wherein 0 < y < 1, wherein 0 < z < 0.05, and wherein y + z < 1.

[0052] Further, the luminescent material may comprise a SiAlON phosphor, such as selected from the group comprising (a) S112— m— n Alm+nOnNi6-n:Eu2+(a-SiA10N), (b) Si6-nAlnOnN8-n:Eu2+, wherein 0 < n < 4.2 (P-SiAlON), and (c) Si2-nAlnOi+nN2-n:Eu2+, wherein 0 < n < 0.2 (O-SiAlON).

[0053] 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.

[0054] Blue luminescent materials may comprise YSO (Y2SiOs:Ce3+), or similar compounds, or BAM (BaMgAlioOi?:Eu2+), or similar compounds.

[0055] In embodiments, the 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 is in 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.

[0056] A luminescent material of the type M’xM2-2xAX6 doped with tetraval ent manganese is amongst others described in WO2013121355A1, which is herein incorporated by reference. Passages from WO2013121355A1 are also copied herein.

[0057] 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 tetraval ent manganese phosphor, or (tetraval ent) Mn-doped M’xM2-2xAX6 phosphor, or shortly "phosphor".

[0058] The term “luminescent material” herein especially relates to inorganic luminescent materials.

[0059] Hence, when M (or A) in chemical formulas refer to n different elements, this may imply that the relevant formula may comprise for the M (or A) position in the formula essentially any permutation of the n different elements. For instance, when M=Ba,Sr,Ca or when M comprises one or more of Ba, Sr, Ca or when M refers to Ba,Sr,Ca, i.e. n=3, this may imply that in the formula Ba, Sr, Ca, (BaxSry), (BaxCay), (CaxSry), or (BaxSryCaz), may be available, wherein in general x+y+z=l. Referring to e.g. M’xM2-2xAX6, this may refer to e.g. one or more of K2SiFe:Mn4+and of Rb2SiFe n4+, or (KxRby)2SiFe:Mn4+, etc. Referring to (Ba,Sr,Ca)AlSiN3:Eu, this may imply BaAlSiN3:Eu, SrAlSiN3:Eu, CaAlSiN3:Eu, (BaxSry)AlSiN3:Eu, (BaxCay)AlSiN3:Eu, (CaxSry)AlSiN3:Eu, or (BaxSryCaz)AlSiN3:Eu. Referring to e.g. AsBsO Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, this may imply YsfLOn Ce, LasBsOn Ce, GdBsOn Ce, TbsBsOn Ce, Lu3BsOi2:Ce, but also e g. (Yx,Gdy)3BsOi2:Ce, (Yx,Luy)3BsOi2:Ce, (Gdx,Luy)3BsOi2:Ce, (Yx,Gdy,Luz)3B50i2:Ce, etc. etc., with hereby only limiting for the sake of economy to unary, binary, and ternary examples, though quaternary and higher examples are not excluded herein. Further, indications like “K,Rb” or Ba,Sr,Ca, and similar indications (see also above), may indicate one or more of such elements. Hence, (K,Rb)2SiFe:Mn4+, may e.g. refer to K2SiFe:Mn4+and of Rb2SiFe:Mn4+, or (KxRby)2SiFe:Mn4+. Also herein in general x+y=l. Hence, when M (or A) may refer to n different elements, with n being at least two, 2n-l permutations may in principle be possible.

[0060] Alternatively or additionally, also other luminescent materials may be applied. For instance quantum dots and / or organic dyes may be applied and may optionally be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc. etc.. Quantum dots are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots. Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium free quantum dots such as indium phosphide (InP), and copper indium sulfide (CuInS2) and / or silver indium sulfide (AgInS2) can also be used. Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore the emission color can easily be tuned by adapting the size of the quantum dots. Any type of quantum dot known in the art may be used in the present invention. However, it may be preferred for reasons of environmental safety and concern to use cadmium-free quantum dots or at least quantum dots having a very low cadmium content. Instead of quantum dots or in addition to quantum dots, also other quantum confinement structures may be used. The term “quantum confinement structures” should, in the context of the present application, be understood as e.g. quantum wells, quantum dots, quantum rods, tripods, tetrapods, or nanowires, etcetera. Organic phosphors can be used as well. Examples of suitable organic phosphor materials are organic luminescent materials based on perylene derivatives, for example compounds sold under the name Lumogen® by BASF. Examples of suitable compounds include, but are not limited to, Lumogen® Red F305, Lumogen® Orange F240, Lumogen® Yellow F083, and Lumogen® F170. Different luminescent materials may have different spectral power distributions of the respective luminescent material light. Alternatively or additionally, such different luminescent materials may especially have different color points (or dominant wavelengths).

[0061] As indicated above, other luminescent materials may also be possible. Hence, in specific embodiments the luminescent material is selected from the group of divalent europium containing nitrides, divalent europium containing oxynitrides, divalent europium containing silicates, cerium comprising garnets, and quantum structures. Quantum structures may e.g. comprise quantum dots or quantum rods (or other quantum type particles) (see above). Quantum structures may also comprise quantum wells. Quantum structures may also comprise photonic crystals.

[0062] As can be derived from the above, the term “different luminescent materials” may refer to luminescent materials that are different, or to two compositions, each including at least one luminescent material in common, but wherein the compositions differ. For instance, a first luminescent material comprising luminescent materials A and B, and a second luminescent material comprising only A or only B, or comprising both A and B, but in a different weight ratio. Such first luminescent material and second luminescent material may have different spectral power distributions of their respective luminescent material light.

[0063] Especially, the light generating system comprises two luminescent materials. However, more luminescent materials are herein not excluded. Especially, good results, however, were obtained with one or more first luminescent materials of the type of A3BsOi2:Ce3+and one or more second luminescent materials of the (oxy)nitride type (doped with divalent europium). Hence, in embodiments the first luminescent material may at least comprise a luminescent material of the type AsBsOn Ce, 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, and the second luminescent material may at least comprise a luminescent material selected from the group of oxynitride luminescent materials and nitride luminescent materials. In specific embodiment, the second luminescent material may comprise one or more of (i) MAlSiNs:Eu2+, wherein M comprises one or more of Ca, Sr, and Ba, especially one or more of Ca and Sr, such as one or more of CaAlSiHvEu2and (Cax,Sry)AlSiN3:Eu2+(wherein x+y=l, and wherein x>0 and y>0) and (ii) NESis Eu2, M comprises one or more of Ca, Sr, and Ba, especially one or more of Ba and Sr, such as (Bax,Sry)2SisN8:Eu2+(wherein x+y=l, and wherein x>0 and y>0), etc. (see further also above). Especially, the first luminescent material is configured in a light receiving relationship with the first solid state light source and is configured to convert at least part of the first light source light into first luminescent material light. Further, the first luminescent material may provide emission with spectral power in the green-orange wavelength range. Spectral power in the red wavelength range is herein not excluded, but especially the main spectral intensity may be in the green-orange wavelength range. Further, especially the emission light comprises a broad band. Hence, in embodiments the first luminescent material light may have a first spectral power distribution with a first emission band (EMI) having a first centroid wavelength (Xci) selected from the 530-600 nm wavelength range, more especially selected from the wavelength range of 545-590 nm, such as selected from the wavelength range of 550-585 nm. The first emission band may have a first full width half maximum (FWHM1) of at least 70 nm, like at least about 90 nm, such as even at least 100 nm. Note that this emission refers to the intrinsic emission of the selected luminescent material. This does not include absorption by other luminescent materials. Hence, the spectral properties of the first luminescent material when combined with the second luminescent material (and optionally further luminescent materials) may change relative to the spectral properties of the first luminescent material in the absence of the second luminescent material (and optionally further luminescent materials).

[0064] The second luminescent material may especially be applied to provide spectra intensity at larger wavelengths than the first luminescent material. Hence, relatively, its spectral power may be more available in the deep-orange and red wavelength range. As this luminescent material emits at longer wavelength, the excitation light source may be selected from the first solid state light source as well as the first luminescent material. Further, especially the emission light comprises a broad band. Hence, in embodiments the second luminescent material may be configured in a light receiving relationship with one or more of (i) the first solid state light source and (ii) the first luminescent material. Upon receipt of such light, at least part thereof may be converted into second luminescent material light. Hence, the second luminescent material may (further) be configured to convert one or more of (i) at least part of the first light source light and (ii) at least part of the first luminescent material light into second luminescent material light. In embodiments, the second luminescent material light may have a second spectral power distribution with a second emission band (EM2) having a second centroid wavelength (X^) selected from the 605-660 nm wavelength range. Further, the second emission band (EM2) may have a second full width half maximum (FWHM2) of at least 40 nm, such as at least about 50 nm. In embodiments, the second emission band (EM2) may have a second full width half maximum (FWHM2) of at least about 60 nm.

[0065] Note that this emission refers to the intrinsic emission of the selected luminescent material. This does not include absorption by other luminescent materials. Hence, the spectral properties of the second luminescent material when combined with the first luminescent material (and optionally further luminescent materials) may change relative to the spectral properties of the second luminescent material in the absence of the first luminescent material (and optionally further luminescent materials). The spectral impact, however, of the first luminescent material on the spectral properties of the second luminescent material light may be limited.

[0066] The term “centroid wavelength”, also indicated as c, is known in the art, and refers to the wavelength value where half of the light intensity is at shorter and half the intensity 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 Ze = X A* 1(A) / (S I( A)), where the summation is over the wavelength range of interest, and 1(A) 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.

[0067] In embodiments, two (or more) first luminescent materials may be applied. In such embodiments, the first emission band (EMI) may be consists of two (or more) contributions of the respective first luminescent materials. Alternatively or additionally, in embodiments, two (or more) second luminescent materials may be applied. In such embodiments, the second emission band (EM2) may be consists of two (or more) contributions of the respective second luminescent materials. Hence, the term first luminescent material may refer to a single first luminescent material, two (different) first luminescent materials, and optionally more than two (different) first luminescent materials. Likewise, the term second luminescent material may refer to a single second luminescent material, two (different) second luminescent materials, and optionally more than two (different) second luminescent materials.

[0068] Especially, the first luminescent material and the second luminescent material are configured such that nearly all first light source light may be absorbed, or at least essentially all first light source light having a wavelength below 500 nm. In this way, light (“system light”) may be provided that may essentially consist of contributions from the first luminescent material light and the second luminescent material light. Therefore, in embodiments the system light has a spectral power distribution comprising a system light emission band (EMS), wherein the system light emission band (EMS) comprises at least part of the first emission band (EMI) and at least part of the second emission band (EM2). As indicated above, the first luminescent material light may be substantially influenced by the presence of the second luminescent material, whereas the second luminescent material light may (slightly) be altered by the presence of the first luminescent material. Further, the spectral power distribution of the second luminescent material may be altered due to selfabsorption. For this reason, it is indicated that at least part of the respective emission band contributes to the system light. In specific embodiments, the system light emission band (EMS) comprises part of the first emission band (EMI) and a substantial part of the second emission band (EM2). Further, in embodiments, the spectral power distribution of the system light may have in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm. Nevertheless, the system light may in embodiments be (warm) white light and / or have an acceptable CRI. In specific embodiments, the system light may have a color rendering index of at least 60. Further, in embodiments the system light may have a correlated color temperature selected from the range of 1500-3000 K. Hence, the luminescent materials, the configuration of the luminescent materials in the system, and the first solid state light source may be selected such that the spectral power distribution of the system light has in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm, and (c) the system light has a color rendering index of at least 60 and a correlated color temperature selected from the range of 1500-3000 K.

[0069] In embodiments, the first centroid wavelength may be in the range of 550-595 nm. Hence the first luminescent material light may mainly be yellow. In (further) embodiments, the second centroid wavelength may be selected from the range of 615-650 nm. Hence, the second luminescent material light may mainly be in the red. Therefore, in embodiments one or more of the following may apply: (a) 550 nm < Xci < 595 nm, and (b) 615 nm < Xc2 < 650 nm.

[0070] As indicated above, the system light emission band may in embodiments essentially be composed of a contribution of at least part of the first emission band and at least part of the second emission band. This may lead to a relatively broad (and continuous) band having a relatively large full width half maximum, like at least 100 nm, or even more, like at least about 120 nm, or even at least about 140 nm. Therefore, in embodiments the system light emission band (EMS) may have a full width 10% maximum (width) of at least 140 nm (i.e. the width of the line shape at (only) 10% of its maximum amplitude). Hence, at a height relative to the y-axis of 10% of the peak maximum of this band, the band width may be about 140 or more.

[0071] Especially, the system light may in embodiments essentially consist of first luminescent material light and second luminescent material light. Hence, even though in specific embodiments the first luminescent material may comprise a plurality of first luminescent materials and / or in other specific embodiments the second luminescent material may comprise a plurality of second luminescent materials, there may essentially be no further types of luminescent materials. In specific embodiments, the spectral power distribution of the system light may have in a spectral range of 380-780 nm at least 95%, more especially at least about 98%, such as at least 99%, of the spectral power provided by the system light emission band (EMS).

[0072] The relatively broad emission band of the system light may thus be based on (at least) two contributions. The spectral power distribution may be subjected to a spectral deconvolution, using a (first Gaussian-type band (FG1) defined by a) first set of one or more Gaussians, like in embodiments one or two Gaussians, and a (second Gaussian-type band (FG2) defined by a) second set of one or more Gaussians, like in embodiments one or two Gaussians. Of course, this may be an approximation, but it appears to provide very good accordance with the spectral power distribution of the system light emission band. As indicated above, the spectral power distributions of the first luminescent material light and the second luminescent material light, independent of each other, may essentially be fixed. However, when one of the luminescent materials has interaction with the luminescent material light of the other, this may affect the resulting emission band of the former. Hence, dependent upon the combination of the first luminescent material and the second luminescent material (i.e. in dependence of one or parameters like: being mixed, configured in separate layers, relative amounts, relative absorptions of the first light source light, absorption strengths for the first light source light, absorption strength of the first light source light by the second luminescent material, etc.), the resulting emission bands may differ in shape and position. Hence, the first set of one or more Gaussians and / or the second set of one or more Gaussians do not have fixed peak positions. Therefore, different combinations of the first luminescent material and the second luminescent material may lead to different spectral power distributions of the system light emission band, but essentially each of the system light emission bands may be deconvoluted using the first set of one or more Gaussians and the second set of one or more Gaussians. The fits provided R2values of in general at least about 0.95, or even at least about 0.98. Especially, the first Gaussian-type band (FG1) defined by the first set of one or more Gaussians may have a larger area overlapping with the first emission band of the first luminescent material light. For instance in the range of 51-100% of its area may overlap with the first emission band of the first luminescent material light, like selected from the range of 60-100%. Further, the second Gaussian-type band (FG2) defined by the second set of one or more Gaussians may have a larger area overlapping with the second emission band of the second luminescent material light. For instance in the range of 51-100% of its area may overlap with the second emission band of the second luminescent material light, like selected from the range of 80-100%.

[0073] Therefore, in embodiments the system light emission band (EMS) is deconvolutable in (i) a first Gaussian-type band (FG1) having a higher overlap with the first emission band (EMI) than with the second emission band (EM2) and (ii) a second Gaussian- type band (FG2) having a higher overlap with the second emission band (EM2) than with the first emission band (EMI).

[0074] Further, it appears that the first Gaussian-type band (FG1) has a first height (II), the second Gaussian-type band (FG2) has a second height (12), and that the system light may comply with the following function of the (desired) correlated color temperature: 11 / 12 > 2.2*10"4*CCT-0.28 applies. Hence, in embodiments the light generating system may be configured such that at a correlated color temperature CCT of the system light 11 / 12 > 2.2*10"4*CCT-0.28 applies. More especially, the light generating system is configured such that at a correlated color temperature CCT of the system light 11 / 12 > 2.2*10"4*CCT-0.27 applies, like 11 / 12 > 2.2*10"4*CCT-0.26 may apply.

[0075] Further, it appears that the best results may be obtained with an upper limit of about 11 / 12 < 3.25*10"4*CCT-0.387. Hence, in embodiments 11 / 12 < 3.25*10"4*CCT-0.387 may apply. More especially, in embodiments 11 / 12 < 3.25*10"4*CCT-0.397 may apply, like in more specific embodiments 11 / 12 < 3.25*10"4*CCT-0.407 may apply.

[0076] The first luminescent material and / or the second luminescent material may be configured in the reflective mode or in the transmissive mode. Further, it may be possible that one of the first luminescent material and the second luminescent material is configured in the transmissive mode and the other one is configured in the reflective mode. Especially, however, the first luminescent material and the second luminescent material may be configured in the transmissive mode. Such embodiments in the transmissive mode may allow the best control of the spectral power of first light source light that might escape from the system. Hence, in embodiments any first light source light in the system light (if available anyhow), may only end up in the system light after transmission through the first luminescent material and the second luminescent material. As indicated above, the contribution to the spectral power of the system light by the first light source light may be very limited: the spectral power distribution of the system light may have in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm.

[0077] In embodiments, the spectral power distribution of the system light may have in a spectral range of 380-780 nm at least about 0.01% of the spectral power in a wavelength range of 380-499 nm. However, lower values, including 0%, are herein not excluded.

[0078] Whether or not in the transmissive mode, several configurations of the first luminescent material and the second luminescent material are described below.

[0079] In specific embodiments, they may be comprised by a single layer (or single body), and may be homogeneously distributed therein. Hence, in embodiments the system may comprise a luminescent converter, wherein the luminescent converter comprises the first luminescent material and the second luminescent material; wherein the first luminescent material and the second luminescent material are configured mixed. In such embodiments, it may be desirable that the weight percentage of the first luminescent material is higher than of the second luminescent material. Hence, in (further) specific embodiments the luminescent converter may comprise (a) the first luminescent material in a first weight percentage wl, relative to the luminescent converter, and (b) the second luminescent material in a second weight percentage w2, relative to the luminescent converter, wherein wl / w2>2, such as wl / w2>5, like wl / w2>9, more especially wl / w2>10. Yet, in embodiments wl / w2<50. Further, in embodiments the total weight percentage of the first luminescent material and the second luminescent material may be relatively high, and may e.g. be at least 50 wt.% relative to the total weight of the luminescent converter. In specific embodiments, the luminescent converter may have a total luminescent material weight percentage relative to the luminescent converter selected from the range of at least about 60%, and up to about 75%, such as selected from the range of 65-70 wt.%.

[0080] Note that the first luminescent material and the second luminescent material may also be configured in separate layers. For instance, one of the layers is configured upstream to the other (which latter is thus configured downstream of the former). Best results, however, may be obtained when the first luminescent material is configured upstream of the second luminescent material. In this way, first light source light may be substantially attenuated, while having strong luminescence from both the first luminescent material and the second luminescent material. As indicated above, the latter may be able to convert at least part of the first luminescent material light into second luminescent material light. Hence, a high absorption of the first light source light by the first luminescent material may on the one hand be advantageous in terms of reduction of the light source light contribution, and may on the other hand not prevent the second luminescent material of receiving excitation light, as the latter may use first luminescent material light (also) as source of excitation light. Hence, in such embodiments the luminescent converted may comprise a layered structure. Therefore, in embodiments, wherein the system may comprise a luminescent converter, the luminescent converter may comprise a first layer comprising the first luminescent material and a second layer comprising the second luminescent material, wherein in further specific embodiments the second layer is configured downstream of the first layer.

[0081] In embodiments, the first layer may comprise a total amount of luminescent material, comprising first luminescent material, and optionally second luminescent material, wherein especially at least 90 wt%, such as at least 95%, more especially at least 98% of the total weight of the luminescent material in the first layer consists of the first luminescent material. In embodiments, the second layer may comprise a total amount of luminescent material, comprising second luminescent material, and optionally first luminescent material, wherein especially at least 80 wt%, such as at least 85%, more especially at least 95% of the total weight of the luminescent material in the second layer consists of the second luminescent material. Further, in embodiments the first layer may comprise the first luminescent material with a first layer weight percentage (wll), wherein 20 wt.% < wll < 70 wt%, and wherein the second layer comprises the second luminescent material with a second layer weight percentage (wl2), wherein 5 wt.% < wl2 < 70 wt% (such as in embodiments 20 wt.% < wl2 < 70 wt%). The layer percentages relate thus to the weight of the (respective) luminescent material relative to the total weight of the (respective) layer. An advantage of a layered approach would be that a lower phosphor load in the (silicone) resin (that may result in more efficient devices, as package efficiency should increase).

[0082] The first layer may have a first thickness (hl) and the second layer may have a second thickness (h2). In embodiments, 0.5<hl / h2<2. Further, in embodiments the first layer may have a first thickness (hl) larger than a second thickness (h2) of the second layer. For instance, in embodiments hl / h2>1.05, such as about hl / h2>l .1, like in embodiments hl / h2>1.2.

[0083] Further, the luminescent material may be configured in a reflector cup, may be configured as layer in a chip-on board device, may be comprised in encapsulant comprised by a LED filament, etc. Hence, in embodiments the luminescent converter may be configured in a reflector that partially encloses the luminescent converter. In yet other embodiments, the light generating system may comprise a Chip-on-Board (CoB), wherein the Chip-on-Board (CoB) comprises (i) a plurality of the first solid state light sources, and (ii) a luminescent converter, wherein the luminescent converter may be configured (on top of and) at least partially enclosing the plurality of first solid state light sources, and wherein the luminescent converter may comprise the first luminescent material and the second luminescent material. Yet, in (other) embodiments the light generating system may comprise a LED filament, wherein the LED filament may comprise (i) a plurality of the first solid state light sources arranged on an elongated carrier, and (ii) an elongated encapsulant configured in physical contact with and covering the plurality of first solid state light sources and at least part of the elongated carrier; wherein the elongated encapsulant may comprise the luminescent converter. Further, in (other) embodiments, the luminescent converter may be configured at a non-zero distance (di) from the solid state light source (i.e. a “remote” application). In any of the aforementioned embodiments, the luminescent converter may comprise a mixture of the first luminescent material and the second luminescent material or may comprise a layer structure, wherein one of the layers may essentially consist of the first luminescent material, and another one of the layers may essentially consist of the second luminescent material.

[0084] In this way system light may be provided, which may have a CRI of at least about 60, more especially, the CRI may be about 65 or more, though at least 70, or even higher, may also be possible. Yet, in embodiments the color point of the system light may be within about 10 SDCM (standard deviation of color matching), such as within about 7 SDCM of the black body locus (BBL). Further, in embodiments the color point may be relatively close to the locus of the color space. Hence, in embodiments one or more of the following may apply: (i) the system light may have a color rendering index of at least 70, (ii) the system light may have a color point within 10 SDCM from the BBL in the CIE 1931 color space, and (iii) the system light may have a u’ color point value within 7 points, such as within 5 points from the locus in the CIE 1976 color space. Hence, in embodiments the color point of the system light may be close to the outer locus.

[0085] 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.

[0086] The term “white light”, and similar terms, herein, is known to the person skilled in the art. It may especially relate to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700- 20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700 K and 6500 K. In embodiments, e.g. for backlighting purposes, or for other purposes, the correlated color temperature (CCT) may especially be in the range of about 7000 K and 20000 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.

[0087] The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. Herein, UV may especially refer to a wavelength selected from the range of 190-380 nm, such as 200-380 nm. The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

[0088] The terms “violet light” or “violet emission”, and similar terms, may especially relate to light having a wavelength in the range of about 380-440 nm. In specific embodiments, the violet light may have a centroid wavelength in the 380-440 nm range. The terms “blue light” or “blue emission”, and similar terms, may especially relate to light having a wavelength in the range of about 440-490 nm (including some violet and cyan hues). In specific embodiments, the blue light may have a centroid wavelength in the 440-490 nm range. The terms “green light” or “green emission”, and similar terms, may especially relate to light having a wavelength in the range of about 490-560 nm. In specific embodiments, the green light may have a centroid wavelength in the 490-560 nm range. The terms “yellow light” or “yellow emission”, and similar terms, may especially relate to light having a wavelength in the range of about 560-590 nm. In specific embodiments, the yellow light may have a centroid wavelength in the 560-590 nm range. The terms “orange light” or “orange emission”, and similar terms, may especially relate to light having a wavelength in the range of about 590-620 nm. In specific embodiments, the orange light may have a centroid wavelength in the 590-620 nm range. The terms “red light” or “red emission”, and similar terms, may especially relate to light having a wavelength in the range of about 620-750 nm. In specific embodiments, the red light may have a centroid wavelength in the 620-750 nm range. The terms “cyan light” or “cyan emission”, and similar terms, especially relate to light having a wavelength in the range of about 490-520 nm. In specific embodiments, the cyan light may have a centroid wavelength in the 490-520 nm range. The terms “amber light” or “amber emission”, and similar terms, may especially relate to light having a wavelength in the range of about 585-605 nm, such as about 590-600 nm. In specific embodiments, the amber light may have a centroid wavelength in the 585-605 nm range. The phrase “light having one or more wavelengths in a wavelength range” and similar phrases may especially indicate that the indicated light (or radiation) has a spectral power distribution with at least intensity or intensities at these one or more wavelengths in the indicate 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 440-490 nm wavelength range.

[0089] 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.

[0090] However, the lighting device may also be an outdoor lighting device or a laboratory lighting device. Therefore, in an aspect, the invention also provides a lighting device selected from the group of a lamp, a luminaire, an outdoor lighting device, and a laboratory lighting device, comprising the light generating system as described herein. Further, the lighting device may also be an industrial manufacturing factory lighting device or a processing factory lighting device. Hence, in an aspect the invention also provides a lighting device selected from the group of an industrial manufacturing factory lighting device or processing factory lighting device comprising the light generating system as described herein.

[0091] 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 first light sources.

[0092] BRIEF DESCRIPTION OF THE DRAWINGS

[0093] 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:

[0094] Figs, la-lf schematically depict some embodiments;

[0095] Figs. 2a-2b show some spectral power distributions; and

[0096] Fig. 3 schematically depict some indoor applications (though outdoor applications are herein also part of the invention).

[0097] The schematic drawings are not necessarily to scale.

[0098] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0099] Figs, la-ld schematically depict embodiments of a light generating system 1000 comprising a first solid state light source 10, a first luminescent material 210, and a second luminescent material 220. The first solid state light source 10 may be configured to generate first light source light 11 having a peak wavelength selected from the 430-490 nm wavelength range, such as selected from the 445-455 nm wavelength range. The first luminescent material 210 may be configured in a light receiving relationship with the first solid state light source 10 and may be configured to convert at least part of the first light source light 11 into first luminescent material light 211. The first luminescent material light 211 may have a first spectral power distribution with a first emission band EMI having a first centroid wavelength Xci selected from the 530-600 nm wavelength range and a first full width half maximum FWHM1 of at least 70 nm. The second luminescent material 220 may be (a) configured in a light receiving relationship with one or more of (ai) the first solid state light source 10 and (aii) the first luminescent material 210, and may be (b) configured to convert one or more of (bi) at least part of the first light source light 11 and (bii) at least part of the first luminescent material light 211 into second luminescent material light 221. The second luminescent material light 221 may have a second spectral power distribution with a second emission band EM2 having a second centroid wavelength Ki selected from the 605-660 nm wavelength range and a second full width half maximum FWHM2 of at least 50 nm. Especially, the light generating system 1000 may be configured to generate system light 1001, wherein: (a) the system light 1001 may have a spectral power distribution comprising a system light emission band EMS, wherein the system light emission band EMS comprises at least part of the first emission band EMI and at least part of the second emission band EM2, (b) the spectral power distribution of the system light 1001 may have in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm, and (c) the system light 1001 may have a color rendering index of at least 60 and a correlated color temperature selected from the range of 1500-3000 K.

[0100] In embodiments, one or more of the following applies: (a) 550 nm < Xci < 595 nm, and (b) 615 nm < < 650 nm. In embodiments, the system light emission band EMS may have a full width at 10% of maximum height of at least 100 nm, such as at least 120 nm, even more especially at least about 140 nm. Hence, the system light emission band EMS may have a full width 10% maximum of at least 140 nm. In embodiments, the spectral power distribution of the system light 1001 may have in a spectral range of 380-780 nm at least 99% of the spectral power provided by the system light emission band EMS.

[0101] Referring to Figs, la-lf, in embodiments, the first luminescent material 210 and the second luminescent material 220 are configured in the transmissive mode.

[0102] Referring to Figs, la-le, in embodiments the system 1000 may comprise a luminescent converter 2000 comprising the first luminescent material 210 and the second luminescent material 220.

[0103] Referring to Figs, la-le, in embodiments, the first luminescent material 210 and the second luminescent material 220 are configured mixed.

[0104] In embodiments, the luminescent converter 2000 may comprise (a) the first luminescent material 210 in a first weight percentage wl, relative to the luminescent converter 2000, and (b) the second luminescent material 220 in a second weight percentage w2, relative to the luminescent converter 2000, wherein wl / w2>9, such as wl / w2>10.

[0105] In embodiments, the luminescent converter 2000 may have a total luminescent material weight percentage relative to the luminescent converter 2000 selected from the range of 65-70 wt.%.

[0106] Referring to Fig. la, the luminescent converter 2000 may be configured in a reflector cup. Side reflectors are indicated with reference 1005. At the bottom may also be a reflector, indicated with reference 1006), the reflector may especially be reflective for light source light 11 and luminescent material light 211,221. Hence, in embodiments, the luminescent converter 2000 may be configured in a reflector 1005 that partially encloses the luminescent converter 2000.

[0107] Referring to Fig. lb a remote configuration is schematically depicted, with by way of example two first light sources 10. In embodiments, the luminescent converter 2000 may be configured at a non-zero distance di from the solid state light source 10.

[0108] Referring to Fig. 1c, a view of a LED filament 400 is depicted. The LED filament 400 , may especially comprise a plurality of the corresponding solid state light source 10 arranged on an elongated carrier 5, wherein the plurality of solid state light sources 10 and at least part of the elongated carrier 5 may be covered by a corresponding encapsulant 410. The plurality of solid state light sources 10 may be configured on both major surfaces of the elongated carrier 5 (as depicted in Fig. 1c), or on only one of the major surfaces of the elongated carrier 5. Similarly, the encapsulant 410 may (at least partially) cover both major surfaces of the elongated carrier 5 (as depicted in Fig. 1c), or on only one of the major surfaces of the elongated carrier 5. The carrier may be transmissive for the light source light 11. Hence, in embodiments, the light generating system 1000 may comprise a LED filament 400. The LED filament 400 may comprise (i) a plurality of the first solid state light sources 10 arranged on an elongated carrier 5, and (ii) an elongated encapsulant 410 configured in physical contact with and covering the plurality of first solid state light sources 10 and at least part of the elongated carrier 5. In embodiments, the elongated encapsulant 410 may comprise the luminescent converter 2000.

[0109] Referring to Fig. Id, the first light source 10 may be enclosed by a lens-like encapsulant or luminescent converter 2000. Reference 6 refers to a support, such as a PCB.

[0110] With reference to Fig. le, in embodiments, the light generating system 1000 may comprise a Chip-on-Board CoB 500. In embodiments, the Chip-on-Board CoB 500 may comprise (i) a plurality of the first solid state light sources 10, and (ii) a luminescent converter 2000. In embodiments, the luminescent converter 2000 may be configured (on top of and) at least partially enclosing the plurality of first solid state light sources 10. In embodiments, the luminescent converter 2000 comprises the first luminescent material 210 and the second luminescent material 220. Reference 6 indicated a support, such as a PCB.

[0111] Referring to Fig. If, in embodiments, the luminescent converter 2000 may comprise a first layer 2100 comprising the first luminescent material 210 and a second layer 2200 comprising the second luminescent material 220. In embodiments, second layer 2200 may be configured downstream of the first layer 2100 (i.e. the first layer 2100 is configured between the first light source 10 and the second layer 2200). Further, in embodiments, the first layer 2100 may comprise the first luminescent material 210 with a first layer weight percentage wll, wherein 20 wt.% < wll < 70 wt%. Further, in embodiments, the second layer 2200 may comprise the second luminescent material 220 with a second layer weight percentage wl2, wherein 20 wt.% < wl2 < 70 wt%. For instance, layered devices in which the first layer contains the garnet phosphor (e.g. about 45 wt%) covered with a thin second layer that contains a low loading of red nitride (e.g. about 10 wt%), resulted in devices having a CCT of about 2000 K, a CRI of at least 64 and a spectral power percentage below 500 nm of <1%.

[0112] Note that in Figs, la-ld mixed systems are schematically depicted, though layered systems, like depicted in Fig. le, may alternatively be applied in the embodiments as schematically depicted in Figs, la-ld.

[0113] In some outdoor areas, lighting (almost) without blue is required (e.g. near some space observatories). Further, it appears desirable to move to less blue light in outdoor to decrease light pollution (“dark sky”) and disturbance of animals. Also, in some indoor applications appear to require low blue content (e.g. cleanroom lighting and nightlight, respectively). In embodiments, it appears desirable that the lighting spectrum is allowed to generate max 1% of the radiant power in the 380-499 nm range, but the spectrum should have a CRI >60. Current solutions do not seem to provide both conditions.

[0114] Referring got Figs. 2a-2b, spectral power distributions are shown wherein light of a blue LED is convert a combination of a yellow and red phosphor. The emission spectrum of the yellow phosphor is strongly modified due to the strong re-absorption process by the red phosphor. Here, the spectral power distributions EMI refers to the spectral power distribution of the first luminescent material 210 in the absence of the second luminescent material 220. Here, Xci is the centroid wavelength of this spectral power distribution EMI. Reference FWHM1 refers to the full width half maximum of this spectral power distribution EMI. Here, the spectral power distributions EM2 refers to the spectral power distribution of the second luminescent material 220 in the absence of the first luminescent material 210. Here, is the centroid wavelength of this spectral power distribution EM2. Reference FWHM2 refers to the full width half maximum of this spectral power distribution EM2.

[0115] When the first luminescent material 210 and the second luminescent material are available as luminescent converter 2000 (see also above), the luminescent materials may have impact on the spectral power distribution of each other. Especially, the longer wavelength emitting second luminescent material may absorb part of the first luminescent material light 211 of the first luminescent material, thereby having impact on the shape of the resulting emission band of the first luminescent material from the luminescent converter 2000. In Fig. 2a, reference EMS refers to the spectral power distribution of the combined emission, and thus in embodiments effectively the system light 1001. Hence, EMS may also refer to the system light emission band. The reference FW10M refers to the width of the spectral power distribution EMS at 10 percent of its maximum height. Its widths is considerable.

[0116] Referring to Fig. 2b, which is on an energy scale (reciprocal cm) in embodiments, the system light emission band EMS may be deconvolutable in (i) a first Gaussian-type band FG1 having a higher overlap with the first emission band EMI than with the second emission band EM2 and (ii) a second Gaussian-type band FG2 having a higher overlap with the second emission band EM2 than with the first emission band EMI. In embodiments, the first Gaussian-type band FG1 may have a first height II. Further, in embodiments, second Gaussian-type band FG2 may have a second height 12. Reference F refers to the fit with the first Gaussian-type band FG1 and the second Gaussian-type band FG2 of the spectral power distribution EMS. Note that the system light 1001 essentially consists of the system light emission band EMS; there is essentially no blue light.

[0117] In embodiments, the light generating system 1000 may be configured such that at a correlated color temperature CCT of the system light 1001 11 / 12 > 2.2*10'4*CCT-0.28 applies. Further, in embodiments, the light generating system 1000 may be configured such that at a correlated color temperature CCT of the system light 1001 Il / I2< 3.25*10'4*CCT- 0.387 applies.

[0118] In embodiments, the system light 1001 may have a color rendering index of at least 70, may have a color point within 10 SDCM from the BBL in the CIE 1931 color space, and may have a u’ color point value within 5 points from the locus in the CIE 1976 color space.

[0119] In embodiments, the first luminescent material 210 may at least comprise a luminescent material of the type AsBsOn Ce, 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. In embodiments, the second luminescent material 220 may at least comprise a luminescent material selected from the group of oxynitride luminescent materials and nitride luminescent materials.

[0120] Fig. 3 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. 3 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. 3 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. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 to a ceiling; reference 1307 refers to a wall.

[0121] 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” 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.

[0122] 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.

[0123] 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.

[0124] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0125] 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 software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein.

[0126] 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.

[0127] 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.

[0128] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) comprising a first solid state light source(10), a first luminescent material (210), and a second luminescent material (220), wherein: the first solid state light source (10) is configured to generate first light source light (11) having a peak wavelength selected from the 430-490 nm wavelength range; the first luminescent material (210) is configured in a light receiving relationship with the first solid state light source (10) and is configured to convert at least part of the first light source light (11) into first luminescent material light (211); wherein the first luminescent material light (211) has a first spectral power distribution with a first emission band (EMI) having a first centroid wavelength (Xci) selected from the 530-600 nm wavelength range and a first full width half maximum (FWHM1) of at least 70 nm; the second luminescent material (220) is (a) configured in a light receiving relationship with one or more of (ai) the first solid state light source (10) and (aii) the first luminescent material (210), and is (b) configured to convert one or more of (bi) at least part of the first light source light (11) and (bii) at least part of the first luminescent material light (211) into second luminescent material light (221); wherein the second luminescent material light (221) has a second spectral power distribution with a second emission band (EM2) having a second centroid wavelength (X^) selected from the 605-660 nm wavelength range and a second full width half maximum (FWHM2) of at least 50 nm; the light generating system (1000) is configured to generate system light (1001), wherein: (a) the system light (1001) has a spectral power distribution comprising a system light emission band (EMS), wherein the system light emission band (EMS) comprises at least part of the first emission band (EMI) and at least part of the second emission band (EM2), (b) the spectral power distribution of the system light (1001) has in a spectral range of 380-780 nm less than 1% of the spectral power in a wavelength range of 380-499 nm, and (c) the system light (1001) has a color rendering index of at least 60 and a correlated color temperature selected from the range of 1500-3000 K; and wherein the system light emission band (EMS) is deconvolutable in (i) a first Gaussian- type band (FG1) having a higher overlap with the first emission band (EMI) than with the second emission band (EM2) and (ii) a second Gaussian-type band (FG2) having a higheroverlap with the second emission band (EM2) than with the first emission band (EMI); wherein the first Gaussian-type band (FG1) has a first height (II), wherein the second Gaussian -type band (FG2) has a second height (12); wherein the light generating system (1000) is configured such that at a correlated color temperature CCT of the system light (1001) 11 / 12 > 2.2*10'4*CCT-0.28 applies.

2. The light generating system (1000) according to claim 1, wherein one or more of the following applies: (a) 550 nm < Xci < 595 nm, and (b) 615 nm < Xc2 < 650 nm; wherein the system light emission band (EMS) has a full width at 10% of maximum height of at least 140 nm; wherein the spectral power distribution of the system light (1001) has in a spectral range of 380-780 nm at least 99% of the spectral power provided by the system light emission band (EMS); and wherein the first luminescent material (210) and the second luminescent material (220) are configured in the transmissive mode.

3. The light generating system (1000) according to any one of the preceding claims, wherein 11 / 12 > 2.2*10'4*CCT-0.26 applies.

4. The light generating system (1000) according to claim 3, wherein 11 / 12 <3 25*10’4*CCT-0.387 applies.

5. The light generating system (1000) according to any one of the preceding claims 1-4, comprising a luminescent converter (2000), wherein the luminescent converter (2000) comprises the first luminescent material (210) and the second luminescent material (220); wherein the first luminescent material (210) and the second luminescent material (220) are configured mixed.

6. The light generating system (1000) according to claim 5, wherein the luminescent converter (2000) comprises (a) the first luminescent material (210) in a first weight percentage wl, relative to the luminescent converter (2000), and (b) the second luminescent material (220) in a second weight percentage w2, relative to the luminescent converter (2000), wherein wl / w2>9.

7. The light generating system (1000) according to any one of the preceding claims 5-6, wherein the luminescent converter (2000) has a total luminescent material weightpercentage relative to the luminescent converter (2000) selected from the range of 65-70 wt.%.

8. The light generating system (1000) according to any one of the preceding claims 1-4, comprising a luminescent converter (2000), wherein the luminescent converter (2000) comprises a first layer (2100) comprising the first luminescent material (210) and a second layer (2200) comprising the second luminescent material (220), wherein the second layer (2200) is configured downstream of the first layer (2100).

9. The light generating system (1000) according to claim 8, wherein the first layer (2100) comprises the first luminescent material (210) with a first layer weight percentage (wll), wherein 20 wt.% < wll < 70 wt%, and wherein the second layer (2200) comprises the second luminescent material (220) with a second layer weight percentage (wl2), wherein 5 wt.% < wl2 < 70 wt%.

10. The light generating system (1000) according to any one of the preceding claims 5-9, wherein the luminescent converter (2000) is configured in a reflector (1005) that partially encloses the luminescent converter (2000).

11. The light generating system (1000) according to any one of the preceding claims 5-9, wherein the light generating system (1000) comprises a Chip-on-Board (CoB) (500), wherein the Chip-on-Board (CoB) (500) comprises (i) a plurality of the first solid state light sources (10), and (ii) a luminescent converter (2000), wherein the luminescent converter (2000) is configured at least partially enclosing the plurality of first solid state light sources (10), and wherein the luminescent converter (2000) comprises the first luminescent material (210) and the second luminescent material (220).

12. The light generating system (1000) according to any one of the preceding claims 5-9, wherein the light generating system (1000) comprises a LED filament (400), wherein the LED filament (400) comprises (i) a plurality of the first solid state light sources (10) arranged on an elongated carrier (5), and (ii) an elongated encapsulant (410) configured in physical contact with and covering the plurality of first solid state light sources (10) and at least part of the elongated carrier (5); wherein the elongated encapsulant (410) comprises the luminescent converter (2000).

13. The light generating system (1000) according to any one of the preceding claims, wherein the first luminescent material (210) at least comprises a luminescent material of the type AsBsO Ce, 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, and wherein the second luminescent material (220) at least comprises a luminescent material selected from the group of oxynitride luminescent materials and nitride luminescent materials.

14. The light generating system (1000) according to any one of the preceding claims, wherein the system light (1001) has a u’ color point value within 5 points from the locus in the CIE 1976 color space, and wherein one or more of the following applies: (a) the system light (1001) has a color rendering of at least 75, and (b) the system light (1001) has a color point within 10 SDCM from the BBL in the CIE 1931 color space.

15. A lighting device (1200) selected from the group of a lamp (1), a luminaire(2), an outdoor lighting device, a laboratory lighting device, a manufacturing factory lighting device, a processing factory lighting device, comprising the light generating system (1000) according to any one of the preceding claims.

Images