Light generating device
Patent Information
- Application Number
- PCT/EP2026/056966
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-05-16
- Filing Date
- 2026-03-12
- Publication Date
- 2026-09-24
Smart Images
Figure EP2026056966_24092026_PF_FP_ABST
Abstract
Description
[0001] 2025P80074EP01
[0002] 1
[0003] LIGHT GENERATING DEVICE
[0004] FIELD OF THE INVENTION
[0005] The invention relates to a light generating device comprising a luminescent converter. The invention further relates to a lighting system comprising the light generating device.
[0006] BACKGROUND OF THE INVENTION
[0007] Light generating devices comprising luminescent materials are known in the art. Such light generating devices may include PC LEDs (phosphor converter LEDs) and may include luminescent materials that have emission with a centroid wavelength in the orange-red wavelength range.
[0008] US2013 / 334957A1) discloses a lighting unit with a tin phosphate glass containing embedded luminescent material particles, wherein the luminescent material particles comprise luminescent material from the class of CaAlSiNvEu2and optionally other luminescent material particles.
[0009] ZHANG YUJIE ET AL: " A high quantum efficiency CaAlSiNvEu2phosphor-in-glass with excellent optical performance for white light-emitting diodes and blue laser diodes", CHEMICAL ENGENEERING JOURNAL, vol. 401, 1 December 2020, page 125983, discloses a warm-white LED having a CaAlSiNvEu2phosphor dispersed into a glass matrix in a remote configuration.
[0010] SUMMARY OF THE INVENTION
[0011] Quenching of luminescent materials when using a high intensity light source, instead of a LED, such as a laser diode, for excitation of a luminescent material refers to a phenomenon where the luminescence of the luminescent material deteriorates due to a relatively high light intensity. The deterioration may happen due to various reasons such as thermal effects and energy -transfer up-conversion. Quenching can affect the performance and efficiency of the luminescent material in lighting applications.
[0012] Laser sources can be used to create light sources with a brightness far higher than what’s possible with LEDs. To generate white light from the blue (pump) laser, often a2025P80074EP01
[0013] 2
[0014] garnet phosphor is used, resulting in white light with a high correlated color temperature (CCT) and low color rendering index (CRI). Neutral white color points can be realized using a blue laser in combination with a garnet phosphor, but then the color point is far above black body locus (BBL), with a low CRI. For automotive and entertainment applications, that might be good enough, but for general lighting applications a lower CCT, a color point closer to the BBL, and better color rendering may be required.
[0015] In the case of LEDs, the lower CCTs / improved color rendering may be obtained by using blue LEDs in combination with a yellow / green (garnet) phosphor and a red nitride phosphor. Using the same approach for sources with a higher brightness may result in severe (photo)quenching of the red phosphor, resulting in a larger color point shift with increased irradiance of blue laser pump at higher driving conditions and a low efficiency (quantum efficiency (QE) of the red phosphor decreases strongly with increasing irradiance).
[0016] The use of red phosphors in laser applications may be needed to achieve lower CCTs with color points closer to, or on, the BBL and / or higher color rendering. The red phosphors may, however, be more prone to photo saturation / quenching, resulting in relatively large color shifts with increased irradiance under higher driving conditions and low efficiency. A bigger effect of photo quenching for red phosphors may be expected based on the slower decay rate of the Eu2+activator, compared to Ce3+, the activator in yellow green garnet phosphors (1-2 ps vs 40 ns).
[0017] The present invention may have as an object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
[0018] To minimize the effect of photo saturation / quenching, herein a low-doped red nitride phosphor in combination with a yellow / green garnet phosphor is proposed, which may result in a more stable color point and a smaller decrease of efficiency with increasing driving current enabling applications of high color quality high brightness laser-phosphor sources in general lighting. Especially, the Eu2+dopant concentration may be below about 0.5 mol% to reduce the photo saturation / quenching of the red phosphor. However, by reducing the activator concentration the centroid wavelength (as a measure for the color point) of the red nitride phosphor emission significantly shifts to shorter wavelengths. Therefore, the composition of the red phosphor may be adjusted to compensate for the blue shift with decreasing dopant concentration. In combination with a blue laser, white light with a low CCT (e.g. < 5000K) and decent color rendering can be realized.
[0019] According to a first aspect, herein a light generating device is provided, configured to generate device light. Especially, the light generating device may comprise a2025P80074EP01
[0020] 3
[0021] solid-sate light source and a luminescent converter. The solid-state light source is especially configured to generate source light having a source light peak wavelength (sc), especially selected from the range of 380 - 495 nm. Further, the solid-state light source may especially be selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes. Yet, the luminescent converter may comprise a first luminescent material and a second luminescent material. Especially, the first luminescent material may be configured to convert at least part of the source light into first luminescent material light. Yet, especially the second luminescent material may be configured to convert at least part of the source light into second luminescent material light. Further, the first luminescent material may comprise a luminescent material of the type AsEEOn Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, wherein B comprises one or more of Al, Ga, In and Sc. Yet, the second luminescent material may comprise a luminescent material of the type MAlSiHvEu2(“SCASN” or “CASN”), wherein M comprises one or more of Ba, Sr, and Ca, and wherein the amount of Eu is at most 0.7 mole %. Yet further, the first luminescent material light may have a first chromaticity coordinate uf in the CIE u’v’ color diagram in the range of 0.12 < uf < 0.21. Yet, the second luminescent material light may have a second chromaticity coordinate U2’ in the CIE u’v’ color diagram in the range of 0.34 < U2’ < 0.46. Further, the device light may comprise at least part of the first luminescent material light, at least part of the second luminescent material light, and optionally part of the source light. Hence, especially herein, a light generating device according to claim 1 is provided. Here, u’ and v’ are color coordinates of the light in the CIE 1976 UCS (uniform chromaticity scale) diagram. The luminescent converter comprises a first layer and a second layer, wherein the first layer comprises a first luminescent material, wherein the second layer comprises a second luminescent material, and wherein the second layer is configured downstream of the first layer. Advantage of this layered structure is that the effect of photo saturation / quenching of the low-doped red nitride phosphor is even further minimized as it is not directly exposed to the source light.
[0022] Especially, A may comprise one or more of Y, Gd and Lu. Further, especially B may comprise one or more of Al and Ga. More especially, at least 90 mole % of A may consist of one or more of Y and Lu, and wherein at least 90 mole% of B consists of one or more of Al and Ga. Yet more especially, at least 90 mole % of A may consist of one or more of Y and Lu, and wherein at least 90 mole% of B may consist of Al. Further, M may comprise one or more of Ca and Sr. Yet, more especially selected from the range of 0.2-0.5 mole% of M may consist of Eu. Yet, particularly at least 90 mole % of M may consist of one2025P80074EP01
[0023] 4
[0024] or more of Ca and Sr. It appears that when going to higher CCT and / or to lower CRI, the Sr concentration may be chosen to be higher, whereas when going to lower CCT and / or higher CRI, the Ca concentration may be chosen to be higher. Yet more particularly, dependent upon the choice of CCT and / or CRI, herein at least 80 mole % of M may consists of Ca. When the Eu concentration is very low, it may, however, be desirable to have relatively higher concentrations of Sr in order to be able to use a higher [Eu] (resulting in a higher absorption strength). Especially, in order to obtain a relatively low U2’ a very low europium concentration in a Ca rich CASN material may be applied, or some of the Ca may be replaced with Sr while increase the europium concentration. Herein, for instance, at least 99 mole % of M may consist of (a) Eu and (b) one or more of Ca and Sr, and selected from the range of 0.2-0.5 mole% of M may consist of Eu. Especially, these choices may provide relatively low quenching. Further, especially these choice may allow a relatively high efficiency, and / or a relatively high CRI, and / or a relatively high lumen equivalence.
[0025] 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” or “luminescent converter material” 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.
[0026] 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.
[0027] 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.
[0028] The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below.2025P80074EP01
[0029] 5
[0030] 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.
[0031] 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.sgCeo.o sAhOn. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art.
[0032] 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)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.
[0033] 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. Hence, the phrase “M comprises one or more of Sr and Ba”, and similar phrases, may in fact indicate SrxBay, wherein 0<x<l, 0<y<l, and x+y=l. Likewise, the phrase “M comprises one or more of Ca, Sr, and Ba”, and similar phrases, may in fact indicate CaxSryBaz, wherein 0<x<l, 0<y<l, 0<z<l and x+y+z=l. Hence, when M (or A), etc. may refer to n different elements, with n being at least two, 2n-l permutations may in principle be possible.
[0034] Here, at least 90 vol.%, such as at least 95 vol.%, more especially at least 98 vol.%, such as 100 vol.% of the luminescent material may consist of (a) the first luminescent material and (b) the second luminescent material. Note that the term “first luminescent2025P80074EP01
[0035] 6
[0036] material” may refer to a singly type of first luminescent material, like (Yo.iLuo.89Ceo.oi)3A150i2, but may also refer to two or more first luminescent materials, like (Yo.98Luo.iCeo.oi)3A150i2. and (Yo.iLuc Ceo.o sAlsOn. Further, note that the term “second luminescent material” may refer to a singly type of second luminescent material, like (Ca0.995Eu0.005) Al SiNs, but may also refer to two or more second luminescent materials, like (Ca0.995Eu0.005) Al SiNs and (Sro.iCao.895Euo.oo5)AlSiN3.
[0037] Especially, the light generating device may be configured to generate white device light. Especially, the device light may have a CCT selected from the range of 1800 -6500 K and / or a color rendering index of at least 70.
[0038] Hence, for instance, the device light may be white light having a correlated color temperature, CCT, in the range of 1800 - 6500 K and a color rendering index, CRI, of at least 70; wherein U2’ is selected from the range ((a + b* ui’+ c*CCT +d* CCT2+ e* ui’*CCT + f* ui’*CCT2) - A) < u2’ < ((a + b* ui’+ c*CCT +d* CCT2+ e* ui’*CCT + f* ui’*CCT2) + B), wherein CCT is the correlated color temperature of the device light in Kelvin, wherein l*10'3< A < 5*10'3and 1.5*1 O'2< B < 3*10'2, and wherein the parameters a, b, c, d, e and f are selected from the ranges -3.5*10'2< a < 5.6*10-1, -4.18*10-1< b < 3.42, -9.6*10'5< c < 1.70*10'4, -1.90*10'8< d < 8.49*10’9, -1.56*10’3< e < 4.46*10’4and -3.74*10'8< f< 1.77*10'7.
[0039] Especially, for a color rendering index of at least 70 (and especially also an R9 of at least -40), and smaller than 75 (and especially also an R9 smaller than -20), may apply that the parameters a, b, c, d, e and f are respectively: -0.035188, 3.42058, 1.69632* IO'04, -1.90922* IO’08, -1.56602* IO’03, and 1.76417* IO’07
[0040] Further, especially for a color rendering index of at least 75 and especially also an R9 of at least -20), and smaller than 80 (and especially also an R9 smaller than 0), may apply that the parameters a, b, c, d, e and f are respectively: 0.072644, 2.946650, 1.063852* IO’04, -1.276556*1O'08, -1.163253*10-°3, and 1.310682* IO’07
[0041] Yet, for a color rendering index of at least 80 and especially also an R9 of at least 0), and smaller than 85 (and especially also an R9 smaller than 25), may apply that the parameters a, b, c, d, e and f are respectively: 0.473403, 8.487O5*1O'03, -9. O6193*1O'05, 8.48384*1O'09, 3.78497*1O'04, and -3.74518*10-°8.
[0042] Further, for a color rendering index of at least 85 and especially also an R9 of at least 25), and smaller than 90 (and especially also an R9 smaller than 50), may apply that the parameters a, b, c, d, e and f are respectively: 0.394140, 9.21816*1O'01, -3.9O425*1O'05, -3.76464E'10, -8.50526*10-°5, and 3.97474*10-°8.2025P80074EP01
[0043] 7
[0044] Yet further, for a color rendering index of at least 90 and especially also an R9 of at least 50) may apply that the parameters a, b, c, d, e and f are respectively: 0.559201, - 4.181O4*1O’01, -9.59639*1O’05, 3.83210*10-°9, 4.45205* IO’04, and 0.0.
[0045] The parameters A and B may especially be used to indicate a range or marge, wherein the value of U2’ can be defined. Especially, for A < 3*10’3and for B < 2*1 O'2may apply. Yet more especially, the following may apply: A = l*10’3and B = 1.5*10’2.
[0046] Further, it may be desirable that R9 is at least -40. At higher CRTs, R9 may especially be at least 5, e.g. when the CRI is selected 80 or higher. Yet mor especially, the R9 may be at least 55, e.g. when the CRI is selected to be 90 or higher. The selection of the CRI may depend upon the application. For instance, CRI 70 may be fine for outdoor applications, whereas for indoor applications, such as office applications, a CRI of at least 80 may be desirable / requested. For retail and / or high quality indoor lighting a CRI of 90 might be desired.
[0047] Hence, U2’ value (and the ui’ value) may also depend upon the selected CRI, CCT, and R9. Further, it appears that the U2’value may depend upon the chosen peak wavelength of the source light. Hence, especially the device light may be white light having a correlated color temperature, CCT, especially in the range of 1800 - 6500 K and a color rendering index, CRI, of especially at least 70, wherein U2’ is selected from the range (f(CIE ui’,nCCT,nDWL,nCRI,nR9) - A) < u2’ < (f(CIE ui’,nCCT,nDWL,nCRI,nR9) + B). Herein, f(CIE ui’,nCCT,nDWL,nCRI,nR9) = ab+ 6 / >*CIE uf + c / >*nCCT + <fe*nCRI + e / >*nDWL + / z,*nR9 + >*(nCCT)2+ / / / >*(nR9)2+ CIE uf * [ z / >*nCCT +fe*nDWL + Z / >*nR9]
[0048] + nCCT * [ / « / >* nCR I +pj*nDWL + < / >*nR9] +r / >*nCRI*nR9 + s / >*nCCT*(nR9)2. Further, herein nCCT is the value of CCT(K) / 1000; nCRI is the value of CRV100; nDWL is the value of DWL / 450, wherein DWL is the value of the dominant wavelength in nanometer of the source light, wherein nR9 is the value of R9 / 100. Yet, especially the following may apply: ab= -1.523870; bz, = 8.176129; cb= 2.140266*10’1; db= 4.004156*10’1; e / > = 1.661350; f / > = -1.898141*10’2; g / >= 4.200849*1 O’3; h / > = 1.292229* 10’1; ib= 2.298353*10’1; k / > = -8.020100; lb= 8.265873*10’1; m / > = -8.556446*10’2; p / > = -2.227004* 10’1; q / > = 4.439065*10’2; rb= -1.981058*10’1; and sb= -3.083079*1 O’2. Yet, herein for A and B may apply (see also above): l*10’3< A < 5*10’3and 1.5*10’2< B < 3*10’2. More especially, A < 3*10’3and B < 2*10’2. Yet even more especially, A = l*10’3and B = 1.5*10’2.
[0049] Further, especially in the case of high CRI applications, like at least 90, more especially at least 95, ui’ <0.14. At lower CRI values, the first luminescent material light may have a first chromaticity coordinate uf in the CIE u’v’ color diagram in the range of 0.14 <2025P80074EP01
[0050] 8
[0051] uf < 0.21. More especially, ui’ >0.165. For instance, the first luminescent material light may have a first chromaticity coordinate uf in the CIE u’v’ color diagram in the range of 0.165 < uf < 0.21.
[0052] Further, the second luminescent material light may have a second chromaticity coordinate U2’ in the CIE u’v’ color diagram in the range of 0.375 < U2’ < 0.44. This may especially be beneficial for CRI values of at least about 80.
[0053] For instance, the color rendering index, CRI may be selected from the range of 70 - 80 and the R9 value may be selected from the range of -40 - +5. Especially, the color rendering index, CRI, may be at least 80 (and also especially an R9 of at least 0).
[0054] Alternatively, the color rendering index, CRI may be selected from the range of at least 90 and the R9 value may be selected from the range of at least +50.
[0055] Especially, the source light peak wavelength (sc) may be selected from the range of 440-465 nm. More especially, the source light peak wavelength (sc) may be selected from the range of such as 440-460 nm. For instance, the source light peak wavelength (sc) may be selected from the range of 405 - 490 nm, such as selected from the range of 430 - 475 nm, more especially selected from the range of 435 - 465 nm, most especially selected from the range of 445 - 460 nm.
[0056] Herein, the luminescent converter may comprise a monolithic body comprising the first luminescent material and the second luminescent material. For instance, the luminescent materials may be embedded in a matrix (such as a polymeric matrix (or an inorganic matrix). Or, one of the two luminescent materials is embedded in the other of the luminescent materials.
[0057] Alternatively, however, the luminescent converter may comprise a first layer and a second layer, wherein the first layer comprises the first luminescent material, wherein the second layer comprises the second luminescent material. Especially, the second layer may be configured downstream of the first layer.
[0058] Herein, the terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a 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, along an optical path of the light beam emanating from the light generating means, is “downstream”.
[0059] Herein, the first layer may comprise one of a (i) ceramic first luminescent material, (ii) single-crystalline first luminescent material, and (iii) first matrix material.2025P80074EP01
[0060] 9
[0061] Further, the first luminescent material may comprise first ceramic or single-crystalline luminescent particles being embedded in the first matrix material. Alternatively or additionally, the second layer may comprises one of a (i) ceramic second luminescent material, (ii) single-crystalline second luminescent material, and (iii) a second matrix material. Further, the second luminescent material may comprise second ceramic or singlecrystalline luminescent particles being embedded in the second matrix material. More especially, the first matrix material and the second matrix material may independently be selected from the group of a polymer material, a ceramic material, and a glass material. The polymeric material may e.g. be selected from PMMA, polysiloxanes, etc. Alternatively or additionally, the first matrix material and the second matrix material may independently be selected from the group AI2O3 material, BeO, and other materials with relatively high thermal conductivities.
[0062] The glass material may be a low melting temperature glass material, such as having a melting temperature of at maximum about 500 °C, or even at maximum about 400 °C. Further, note that in general particulate luminescent material may essentially consist of single-crystalline luminescent particles.
[0063] Hence, herein a luminescent element may be applied, wherein the luminescent element comprises the first luminescent material and the second luminescent material. The luminescent element may essentially consist of the first luminescent material and the second luminescent material. However, the luminescent element may also comprise the first luminescent material and the second luminescent material and e.g. a matrix material. The luminescent element may comprise a layered structure, with one layer essentially only comprising the first luminescent material (optionally embedded in a matrix material) and another layer essentially only comprising the second luminescent material (optionally embedded in a matrix material). For instance, the luminescent element may comprise 10-60 vol% of luminescent material and 40-90 vol% of matrix material (and optionally diffuser). As indicated above, for instance at least 90 vol.% of the luminescent material may consist of the first luminescent material and the second luminescent material.
[0064] As indicated above, the light source may especially comprise a laser diode. However, the light generating device may also comprise a plurality of laser diodes, such as a laser bank comprising a plurality of laser diodes. When a plurality of laser diodes is applied as solid state light source(s), then especially their peak wavelengths are within a range of at maximum 15 nm, such as within about 10 nm. Hence, the solid-state light source may comprise a single laser diode, or the light generating device may comprise a plurality of the2025P80074EP01
[0065] 10
[0066] solid-state light sources, wherein each solid-state light source of the plurality of the solid-state light sources comprises a laser diode, wherein the source light peak wavelengths (sc) are selected within a range of at maximum 10 nm. Hence, the source light peak wavelengths (sc) of each individual light source may be within a (predefined) range of 10 nm.
[0067] Further, especially the correlated color temperature, CCT, may be in the range of 2700 - 5000 K.
[0068] Referring to the Ca concentration, it was also found that a relation between a calcium concentration and a europium concentration and U2’ may be defined as:
[0069] CIE u2’=0.372780 + 0.08200210Log [Eu] + 0.15183 [Ca] + 0.002495*(10Log [Eu])2- 0.06979 [Ca]2.
[0070] Herein, [Ca] is the fraction of Ca in the M-site, so between 0 and (1-([Eu] / 100)), and [Eu] is given in mol%. Further, for values of [Ca] may apply that a variation in its fraction is in a range of + / -0.15. Hence, from this formula a desired calcium concentration may be calculated when the desired u2’ value and europium concentration is selected. Especially, for this formula may apply for CaxSryEuzAlSiN3, wherein x+y+z=l.
[0071] The first luminescent material may have a first chromaticity coordinate vf in the CIE u’v’ color diagram in the range of 0.505 < vf < 0.572, preferably in the range of 0.51 < < vf < 0.567. The second luminescent material may have a second chromaticity coordinate v2’ in the CIE u’v’ color diagram in the range of 0.527 < v2’ < 0.554, preferably in the range of 0.532 < v2’ < 0.549. The device light may be white light having a correlated color temperature, CCT, in the range of 1800 - 6500 K and a color rendering index, CRI, of at least 70. In embodiments, the correlated color temperature, CCT, is in the range of 2500 - 5000 K, preferably in the range of 2500 - 4500 K. In an embodiment, the color rendering index, CRI, is at least 80, preferably at least 85. The device light may have a color point with a distance to the black body locus of -0.02 < Duv < +0.02, preferably -0.015 < Duv < +0.015, more preferably 0.01 < Duv < +0.01. The percentage of Eu of the second luminescent material is preferably at least 0.05 %. In an embodiment, the first luminescent material comprises at least 95 % of a luminescent material of the type AsBsOi^Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, wherein B comprises one or more of Al, Ga, In and Sc. In an embodiment, the second luminescent material comprises at least 95 % of a luminescent material of the type MAlSiNvEu2, wherein M comprises one or more of Ba, Sr, and Ca.
[0072] The light generating device 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-optics2025P80074EP01
[0073] 11
[0074] 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, greenhouse lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating device may be part of or may be applied in e.g. optical communication systems or disinfection systems.
[0075] Especially, the light generating device may be applied as lighting device. According to a second aspect, the invention provides a lighting system according to claim 15. The lighting system may consist of the light generating device or may comprise the light generating device and other elements, like e.g. optics. The lighting system may also comprise a plurality of light generating devices (and optionally a controller, configured to control the plurality of light generating devices).
[0076] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating device 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 device light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating device 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 devices such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp and a luminaire, comprising the light generating device as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system.
[0077] In yet a further aspect, the invention also provides a lighting fixture comprising the light generating device as defined herein. Hence, in yet a further aspect, the lighting system may comprise a device selected from the group of a lamp, a luminaire, or a lighting fixture, wherein the lamp, luminaire, or lighting fixture may comprise one or more light generating devices, and the lighting system may further comprise e.g. a control system configured to control the device.2025P80074EP01
[0078] 12
[0079] The term “lighting fixture” may refer to a light emitting system like a moving head, a search light, a stage light, etc. Generally these fixtures may have various control options for changing one or more of the direction of the light (e.g. via gimbals or rotary stages), the beam angle / width (e.g. via zoom optics), the beam pattern (e.g. via mechanical selection of a specific aperture that defines a virtual and patterned source for the further projection optics), the color of the light (e.g. via mechanical selection of a certain color filter), and of course the luminous flux, and mostly these are remotely controllable.
[0080] In embodiments, the lamp or luminaire may be a downlighter or an uplighter. In embodiments, the lamp may comprise a torch.
[0081] The present invention may have the advantage that a light generating device and a lighting system is obtained that have an improved optical performance due to less deterioration of the light output of the luminescent converter when using a solid-state light source having a relatively high luminance.
[0082] Certain embodiments of the invention are provided in the dependent claims. The term “white light”, and similar terms, are known to the person skilled in the art. The term “white light” may especially relate to light having a correlated color temperature (CCT) in the range of 1800-20000 K, such as in the range of 2000-20000 K, especially in the range of 2700-20000 K, for general lighting especially in the range of 2000-7000 K, such as in the range of 2700-6500 K. For other purposes, e.g. for backlighting purposes, the CCT may be in the range of 7000-20000 K. Yet further, the CCT may especially be within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL. The terms “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. Especially for lighting applications, the terms “light” and “radiation” may refer to (at least) visible light. Further, relevant wavelength ranges are indicated below:2025P80074EP01
[0083] 13
[0084] Color of light / radiation / emission: Intensity at (at least) a wavelength in the range of: UV (ultraviolet) 190-380 nm, such as 200-380 nm
[0085] Visible 380-780 nm
[0086] Violet 380-440 nm
[0087] Blue 440-490 nm
[0088] Green 490-560 nm
[0089] Yellow 560-590 nm
[0090] Orange 590-620 nm
[0091] Red 620-780 nm
[0092]
[0093] Here, some further aspects follow, not necessarily limiting the above or the below. A further aspect may also include a light generating device, configured to generate device light, the light generating device comprising a solid-sate light source and a luminescent converter, wherein: (A) the solid-state light source is configured to generate source light having a source light peak wavelength (λsc) selected from the range of 380 - 495 nm, wherein the solid-state light source is selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes; (B) the luminescent converter comprises a first luminescent material and a second luminescent material; (C) the first luminescent material is configured to convert at least part of the source light into first luminescent material light, and wherein the second luminescent material is configured to convert at least part of the source light into second luminescent material light; (D) the first luminescent material comprises a luminescent material of the type A3B5O12:Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, wherein B comprises one or more of Al, Ga, In and Sc; (E) the second luminescent material comprises a luminescent material of the type MAlSiNvEu2, wherein M comprises one or more of Ba, Sr, and Ca, and wherein the amount of Eu is at most 0.7 mole %; (F) the first luminescent material light has a first chromaticity coordinate u1’ in the CIE u’v’ color diagram in the range of 0.12 < ui’ < 0.21; (G) the second luminescent material light has a second chromaticity coordinate u2’ in the CIE u’v’ color diagram in the range of 0.34 < U2’ < 0.46; and (H) the device light comprises at least part of the first luminescent material light, at least part of the second luminescent material light and optionally part of the source light. Especially, in such further aspect A comprises one or more of Y, Gd and Lu, wherein B comprises one or more of Al and Ga. Especially, in such further aspect M comprises one or more of Ca and Sr. Especially, in such further aspect: (i) the device light is white light having a correlated color temperature,2025P80074EP01
[0094] 14
[0095] CCT, in the range of 1800 - 6500 K and a color rendering index, CRI, of at least 70; and (ii) U2’ is selected from the range ((a + b* ui’+ c*CCT +d* CCT2+ e* ui’*CCT + f* ui’*CCT2) -A) < u2’ < ((a + b* ui’+ c*CCT +d* CCT2+ e* ui’*CCT + f* ui’*CCT2) + B), wherein CCT is the correlated color temperature of the device light in Kelvin, wherein A = 5*10-3and B = 3*10-2and wherein the parameters a, b, c, d, e and f are selected from the ranges -3.5*10-2≤ a ≤ 5.6*10-1, -4.18*10-1≤ b ≤ 3.42, -9.6*10-5≤ c ≤ 1.70*10-4, -1.90*10-8≤ d ≤ 8.49*10-9, -1.56*10-3≤ e ≤ 4.46*10-4and -3.74*10-8≤ f ≤ 1.77*10-7. Especially, in such further aspect A = 3*10-3and B = 2*10-2. Especially, in such further aspect A = 1*10-3and B = 1.5*10-2. Especially, in such further aspect the luminescent converter comprises a monolithic body comprising the first luminescent material and the second luminescent material. Especially, in such further aspect (a) the luminescent converter comprises a first layer and a second layer; (b) the first layer comprises the first luminescent material; and (c) the second layer comprises the second luminescent material. Especially, in such further aspect the second layer is configured downstream of the first layer. Especially, in such further aspect: (a) the first layer comprises one of a (i) ceramic first luminescent material, (ii) single-crystalline first luminescent material or (iii) first matrix material and wherein the first luminescent material comprises first ceramic or single-crystalline luminescent particles being embedded in the first matrix material; and (b) the second layer comprises one of a (i) ceramic second luminescent material, (ii) single-crystalline second luminescent material or (iii) a second matrix material and wherein the second luminescent material comprises second ceramic or single-crystalline luminescent particles being embedded in the second matrix material. Especially, in such further aspect the first matrix material and the second matrix material are independently selected from the group of a polymer material, a ceramic material and a glass material.
[0096] Especially, in such further aspect the source light peak wavelength (sc) is selected from the range of 405 - 490 nm, preferably selected from the range of 430 - 475 nm, more preferably selected from the range of 435 - 465 nm, most preferably selected from the range of 445 -460 nm. Especially, in such further aspect the correlated color temperature, CCT, is in the range of 2700 - 5000 K. Especially, in such further aspect the color rendering index, CRI, is at least 80.
[0097] BRIEF DESCRIPTION OF THE DRAWINGS
[0098] 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:2025P80074EP01
[0099] 15
[0100] Figs. 1 A-D schematically depict embodiments of a light generating device comprising a luminescent converter;
[0101] Figs. 2A - 2D schematically depicts further embodiments of a light generating device comprising a luminescent converter;
[0102] Fig. 3 schematically depicts another further embodiment of a light generating device comprising a luminescent converter;
[0103] Fig. 4A shows a graph of the second chromaticity coordinate U2’ (y-axis) versus the first chromaticity coordinate uf (x-axis) for different combinations of first and second luminescent materials;
[0104] Fig. 4B shows CIE u’ color point of (S)CASN phosphors as a function of the dopant concentration and Ca / (Sr+Ca) content.
[0105] Fig. 5 shows the spectrum of the device light for two embodiments of a light generating device.
[0106] Fig. 6 shows the relative light output of a second luminescent material as a function of the irradiance on the second luminescent material by a solid-state light source; and
[0107] Fig. 7 schematically depict embodiments of a lighting system.
[0108] The schematic drawings are not necessarily to scale.
[0109] DETAILED DESCRIPTION OF THE EMBODIMENTS
[0110] Figs. 1 A-D, Fig. 2A - 2D and Fig. 3 schematically depict a light generating device 1000 with a luminescent converter 200. The light generating device 1000 comprises a solid-state light source 10. The luminescent converter 200 is provided in a light receiving relationship with the solid-state light source 10. The luminescent converter 200 comprises a first luminescent material 210 and a second luminescent material 220. In the embodiments according to Figs. 1 A-D, the luminescent converter 200 is provided on the respective solid-state light source 10. In the embodiments of Fig. 2A - 2B, the luminescent converter 200 is configured remotely from the respective solid-state light source 10. The solid-state light source 10 comprises a laser diode, a superluminescent diode or a stacked multi -junction light emitting diode. The solid-state light source 10 is configured to generate light source light 11. The first luminescent material 210 is configured to convert part of the light source light 11 into first luminescent converter light 201. The second luminescent material 220 is configured to convert part of the source light 11 into second luminescent material light 211. The light generating device 1000 is configured to generate device light 1001. The device light 10012025P80074EP01
[0111] 16
[0112] comprises the first luminescent material light 201, the second luminescent material light 211, and optionally non-converted source light 11. In an embodiment, the luminescent converter 200 comprises a monolithic body comprising the first luminescent material 210 and the second luminescent material 220. The monolithic body may be a ceramic body.
[0113] Alternatively, the monolithic body may comprise a matrix material in which the first and the second luminescent materials are embedded, e.g. in the form of first and second luminescent (ceramic or polycrystalline) particles. Alternatively, first luminescent particles are coated with a second luminescent material, or vice versa. The matrix material may comprise a polymer material, a ceramic material or a glass material. The matrix material may further comprise a filler material, comprising thermally conductive particles.
[0114] The first luminescent material 210 comprises a luminescent material of the type A3B5O12:Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, wherein B comprises one or more of Al, Ga, In and Sc. The first luminescent material 210 preferably comprises this type of luminescent material in an amount of at least 90 %, such as at least 95 %, such as 100 %. The second luminescent material 220 comprises a luminescent material of the type MAlSiN3:Eu2+, wherein M comprises one or more of Ba, Sr, and Ca. The second luminescent material 220 preferably comprises this type of luminescent material in an amount of at least 90 %, such as at least 95 %, such as 100 %. The percentage of Eu of the second luminescent material, defined as (100%*mole element Eu / (mole element M + mole element Eu)), is at most 0.7 mole %, preferably at most 0.5 %, such as at most 0.4 %. In an embodiment, the percentage of Eu of the second luminescent material is at least 0.05 %.
[0115] The luminescent converter 200 may further comprise a matrix material 250. The first luminescent material 210 and the second luminescent material 220 may be embedded (distributed) in the matrix material 250. Further, the matrix material 250 may be a polymer matrix material selected from the group of siloxanes. Especially, the polymer matrix material 250 may be selected from the group of dimethylsiloxanes, diphenylsiloxanes, methylphenylsiloxanes, or copolymers thereof. In embodiments, a concentration of the combined first luminescent material 210 and second luminescent material 220 in the matrix material 250 may be in the range of 5 - 90 vol.%, especially in the range of 10 - 80 vol.%, more especially in the range of 30 - 70 vol. %, such as in the range of 40 - 70 vol. %. In other embodiments, the matrix material 250 may comprise a ceramic material or a glass material. In further embodiments, the matrix material further comprises a filler material of thermally conductive (non-luminescent) particles.2025P80074EP01
[0116] 17
[0117] The source light 11 generated by the solid-state light source may especially have a source light peak wavelength λscselected from the range of 380-495 nm, preferably selected from the range of 430 - 475 nm, more preferably selected from the range of 435 -465 nm, most preferably selected from the range of 445 - 460 nm.
[0118] Referring to Figs. 1B-D, a plurality of light generating devices 1000 are shown in each figure, configured in the same housing or on the same support. In embodiments, the plurality of light generating devices 1000 depicted in each of Fig. IB, 1C, and ID, respectively, may be identical, i.e., the two light generating devices 1000 depicted in Fig. IB may be identical to each other, the two light generating devices 1000 depicted in Fig. 1C may be identical to each other, and the plurality of light generating devices 1000 depicted in Fig. ID may be identical to each other. Alternatively, the plurality of light generating devices 1000 depicted in each of Fig. IB, 1C, and ID, respectively, may differ, such as differ in one or more of the respective (type of) solid-state light sources 10, the source light peak wavelengths λscof the respective solid-state light sources 10, the composition of the respective first luminescent material 210, the composition of the respective second luminescent material 220, the concentration ratio of the respective first luminescent material 210 and the second luminescent material 220, or the effective load of the first luminescent material 210 and second luminescent material 220. Yet, all of the plurality of light generating devices 1000 depicted in each of Fig. IB, 1C, and ID may fall under the description of the light generating device 1000 as defined above and in the appended claims. Hence, for clarity, all of the (components of the) light generating devices 1000 in Figs. 1B-D may be indicated using the same references and may be distinguished from each other by the addition of an apostrophe after the reference (e.g., 1000 and 1000’).
[0119] Optionally, referring to Figs. IB and 1C, the light generating devices 1000 may be configured in a housing comprising a light transmissive window, e.g. from polymeric material or glass. Here, the housing is schematically depicted as having a rectangular crosssection. Other types of shapes may also be possible.
[0120] Fig. IB schematically depicts an embodiment of two light generating devices 1000, 1000’ configured to generate respective device light 1001,1001’. In the embodiment depicted in Fig. IB, the luminescent converter 200,200’ may be self-supporting, and may be configured on top of, especially in physical contact with, the respective light source 10,10’.
[0121] Fig. 1C shows embodiments of the light generating devices 1000,1000’ wherein the luminescent converters 200,200’ and solid-state light sources 10,10’ are configured in light reflective cups.2025P80074EP01
[0122] 18
[0123] Fig. ID schematically depicts an embodiment of a strip or an (two-dimensional) array comprising a plurality of light generating devices 1000,1000’.
[0124] In the embodiment depicted in Fig. 1C, the thickness T of the luminescent converters 200,200’ is indicated for the luminescent converter 200’. Here, the shortest distance defining the thickness T may especially be the distance from the part of the luminescent converter 200’ configured in physical contact with a light escape surface of the solid-state light source 10’ to the part of the surface of the luminescent converter 200’ facing away from the solid-state light source 10’ and configured directly above the solid-state light source 10’. This distance may define the thickness T of the luminescent converter 200’, and may further indicate the shortest optical path for the light source light 11 ’ through the luminescent converter 200’. Further, in Fig. 1C, the luminescent converters 200,200’ may be configured as coatings.
[0125] Figs. 2A - 2B schematically depict embodiments of the light generating device 1000 comprising the luminescent converter 200. The luminescent converter 200 may be configured at a non-zero distance di from a (light escape) surface of the solid-state light source 10 facing the luminescent converter 200. For example, as depicted in Fig. 2A, the solid-state light source(s) 10 may be configured at a bottom of a housing, and the luminescent converter 200 may be configured at a light exit window 600 of the housing. Further, as depicted in Figs. 2A - 2B, the luminescent converter 200 comprises the first luminescent material 210 and the second luminescent material 220. In an embodiment, the solid-state light source(s) 10 comprises one or more laser diodes. In Fig. 2A, the luminescent converter is arranged in the transmissive mode and in embodiments no light exit window 600 is present. Referring to Fig. 2B, the luminescent converter 200 is configured in the reflective mode and is configured at a reflector 406. The source light 11 is directed to the luminescent converter 200 via a beam splitting element 408. In this embodiment the beam splitting element 408 is a dichroic mirror 408 being transmissive for the source light 11 and reflective for the first luminescent material light 201 and the second luminescent material light 211. The source light 11 is at least partly converted by the luminescent converter 200. The first luminescent material light 201 and the second luminescent material light 211 are reflected by the beam splitting element 408 towards the light exit of the light generating device 1000. In an embodiment, the solid-state light source 10 comprises one or more laser diodes. In an embodiment, the solid-state light source 10 is a laser bank comprises a two-dimensional array of laser-diodes and optionally optics for collimation of the source light 10. In an alternative2025P80074EP01
[0126] 19
[0127] embodiment, the solid-state light source 10 is a one-dimensional or a two-dimensional multichip laser package.
[0128] Referring to Fig. 2B, the beam splitting element 408 may reflect the luminescent material light 201,211, but essentially not reflect (and only transmit) the (blue) source light 11. In this way, the device light 1001 may be deficient in blue light. This may be solved in several ways, of which one is schematically depicted in Fig. 2C. Here, an additional solid state light source 10 is used, indicated with reference 10’, of which its source light 11, indicated with reference 11’ is added to the luminescent material light 201,211 via an optical path wherein a further beam splitting element 408 element is applied, indicated with reference 408’, which is a polarization based beam splitting element, and which transmit p-polarized light and reflects s-polarized light. The light generating device 1000 may be configured such, that the further source light 11’ comprises p-polarized light. Reference 700 indicates a diffuser, which is configured to maintain polarization of the light. By using a % waveplate, the linear polarized light may be converted into circular polarized light. The diffuser 700 may change its handedness, but the diffused light may still be circular polarized. It is noted that the diffused light after passing second time through the quarter waveplate becomes again liner polarized (here especially with s-polarization), and being reflected from the beamsplitter 408’ it passes dichroic beamsplitter 408 and exits as a part of system light output. A controller (not indicated) may be applied to control the solid state light sources 10, 10’.
[0129] In a variation of the embodiment schematically depicted in Fig. 2c, a non-colinear arrangement of the additional light source 10’ and diffuser may be applied. In such variation, the diffuser 700 may be configured such that the incoming source light 11’ and the reflected diffused source light 711, emanating from the diffuser 700, may have an angle unequal to 180°, but e.g. 90°. In such a variation, the beam splitting element 408’and the 1 / 4 X plate may not be necessary.
[0130] Instead of the reflective mode, also the transmissive mode may be applied. This is schematically depicted in Fig. 2D. Transmission of some blue source light 11 may provide white device light 1001.
[0131] The luminescent converters 200 in the embodiments schematically depicted in Figs. 1 A-1D and 2A-2D and 3, may thus comprise the first luminescent material 210 and the second luminescent material 220.
[0132] Fig. 3 schematically depicts an embodiment of a light generating device 1000 with a luminescent converter 200 that comprises a first layer 401 and a second layer 402. The2025P80074EP01
[0133] 20
[0134] second layer 402 is preferably positioned downstream of the first layer 401. In an embodiment, the first layer comprises a first matrix material 403 and the second layer comprises a second matrix material 404. The first luminescent material 210 is embedded (distributed) in the first matrix material 403, for example in the form of luminescent particles. The second luminescent material 220 is embedded in the second matrix material 404, for example in the form of luminescent particles. The first luminescent particles may be ceramic, single-crystalline or polycrystalline particles. The second luminescent particles may be ceramic single-crystalline or polycrystalline particles. The first matrix material 403 and the second matrix material 404 may comprise a material selected from the group of polymer materials, ceramic materials, glass materials or a filler material comprising thermally conductive particles. In an alternative embodiment, the first layer 401 consists of the first luminescent material 210. In an embodiment, the first layer 401 is a layer of a ceramic first luminescent material or a single-crystalline first luminescent material. In an alternative embodiment, the second layer 402 consists of the second luminescent material 220. In an embodiment, the second layer 402 is a layer of a ceramic second luminescent material or a single-crystalline second luminescent material. In an embodiment, the luminescent converter 200 is configured at a non-zero distance di from a (light escape) surface of the solid-state light source 10, either in the transmissive or in the reflective mode.
[0135] Fig. 4A shows a graph of the second chromaticity coordinate U2’ (y-axis) versus the first chromaticity coordinate uf (x-axis) for different combinations of first luminescent materials 210 and second luminescent materials 220, wherein the device light 1001 has a correlated color temperature of 3000 Kelvin and a CRI of at least 80, and wherein the efficiency of the light generating device 1000 is at least 245 lumen (optical Watt)'1, i.e. at least 245 lumen per Watt of source light 11, taking into account Stokes losses and phosphor quantum efficiency losses, but no optical efficiency losses. The two dashed lines show the upper and lower limit of the range of the second chromaticity coordinate U2’ according to claim 4.
[0136] Fig. 4B shows on the x-axis a logarithmic scale of the Eu concentration, and on the y-axis the U2’ value.. The top slanted line refers to CaAlSiNs (“CASN”) (Ca=l); the other slanted lines refer to SCASN examples: (Cao.8Sro.2)AlSiN3 (Ca=0.8), (Cao.5Sro.s)AlSiN3 (Ca=0.5), (Cao.i2Sro.88)AlSiN3, (Ca=0.12), and the lowest line, refers to SrAlSiNs (SASN) (Ca=0 and Sr=l).
[0137] Note that e.g. (Cao.8Sro.2)AlSiN3: Eu2+(0.5%) may also be indicated as
[0138] (Cao.8Sro.2)o.995Euo.oo5AlSiN3.2025P80074EP01
[0139] 21
[0140] Fig. 5 shows the spectrum of the device light 1001 for two embodiments of a light generating device 1000 according to the invention, for generating device light 1001 having a correlated color temperature of 3000 K, using different source light peak wavelengths and different combinations of a first luminescent material 210 and a second luminescent material 220.
[0141] Fig. 6 shows the relative light output of a second luminescent material 220 as a function of the irradiance on the second luminescent material by source light 11 of a solid-state light source 10, for three different Eu concentrations of the second luminescent material 220: 4 mole % (squares), 2 mole % (triangles) and 0.5 mole % (rhombi). As shown in Fig. 6, in general the relative light output of the second luminescent material 220 decreases at increasing irradiance level. However, for a luminescent converter subject to a source light 11 from a solid-state light source 10 at a relatively high irradiance level, the decrease in the relative light output is limited for Eu concentrations of at most 0.7 %.
[0142] Fig. 7 schematically depicts embodiments of a lighting system 1200 comprising one or more light generating devices 1000 as described above, for example a luminaire 2 comprising one or more of the light generating devices 1000. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the lighting system 1200. In embodiments, the control system 300 may be configured to control the intensity of the system light 1201 in dependence of one or more of an input signal of the user interface 301, a sensor signal, and a timer. Fig. 7 also schematically depicts an embodiment of lamp 1 comprising one or more of the light generating devices 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may comprise one or more of the light generating devices 1000. Reference 4 indicates a stage lighting device. Hence, Fig. 7 schematically depicts embodiments of a lighting system 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3 and a stage lighting device 4, comprising the light generating device 1000 as described herein. System light escaping from the lighting system 1200 is indicated with reference 1201. The system light 1201 may essentially consist of device light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor, reference 1310 refers to a ceiling and reference 1307 refers to a wall.
[0143] Spectra of a laser pumped yellow / green garnet and SCASN red nitride converters were calculated. The target color points were in the warm / neutral white region (2700-5000K, on BBL). Four different pump wavelengths of the laser were used (440, 445,2025P80074EP01
[0144] 22
[0145] 450 and 455 nm) with a FWHM of 3 nm. Data were analyzed using different CRI / R9 requirements for the white light generated: (CRI>71 & R9>-40), (CRI>81 & R9>5) and (CRI>91 & R9>55), which are typical CRI / R9 combinations for white LEDs used in general lighting (outdoor, indoor, indoor high quality / retail applications).
[0146] Highest efficiency is observed for LuYAG or GaYAG garnets in combination with an as short as possible wavelength red phosphor (i.e. lowest CIE u’). Increasing the pump wavelength of the laser appears to have a (small) positive effect on efficiency. In case LuAG-type or YAG-type garnets are used the minimal CIE u’ of the red phosphor is approximately 0.35. Lower values of CIE u’ of the red phosphor may be possible in case more green shifted garnets are used (LuGaAG). These green phosphors may, however, be more susceptible to thermal quenching. With further increase of the CIE u’ of the red nitride phosphor the white light efficiency may decrease, while also the photo saturation / quenching may increase (assuming Ca / Sr ratio is constant). Therefore, a preferred CIE u’ range for this case (3000K, CRI>70) may be ca 0.35 - 0.40 for the red nitride phosphor in combination with ca. 0.14 - 0.19 for the aluminum garnet phosphor. In addition, the Eu2+concentration may be chosen below ca 0.5 mol%.
[0147] If a better color rendering is required (e.g. for indoor applications) a more red-shifted nitride phosphor (longer wavelength red) may be needed. Depending on the chosen garnet phosphor, the minimal CIE u’ of the red phosphor may be increased to 0.37 (in combination with LuGaAG) or even 0.41 (combined with LuYAG). Higher CIE u’ values for the red phosphor may be allowed but may lead to a lower efficiency. Therefore, for 3000K with CRI>80 a preferred CIE u’ range for the red phosphor may be 0.41 - 0.43, with the garnet phosphor chosen with a CIE u’ in the range of ca. 0.14 - 0.19. Also, here the Eu2+concentration may be chosen below ca 0.5 mol%.
[0148] An even higher color rendering quality can only be obtained using LuGaAG phosphors in combination with red nitride phosphors with CIE u’ color point above ~0.42. This may be possible using a (S)CASN phosphor with a Eu2+content below 0.5 mol% and a high Ca / Sr ratio. Therefore, for 3000K with CRI>90 a preferred CIE u’ range for the red phosphor may be 0.42 - 0.44, with the garnet phosphor chosen with a CIE u’ in the range of ca. 0.12 - 0.14. Also, here the Eu2+concentration may be chosen below ca 0.5 mol%.
[0149] The effect on several light source properties was analyzed by decreasing the relative red phosphor QE in steps from 100% to 80%. Surprisingly, the observed white color point shift due to the occurrence of a reduction in QE is smaller in case the most red-shifted green phosphor is used. Also the decrease of the white luminous flux is smaller in that case.2025P80074EP01
[0150] 23
[0151] Using the most blue-shifted garnet on the other hand will lead to stable color rendering properties (CRI, R9) with increasing photo saturation. Since such color point change may be much more pronounced visible (easier to observe, compared to a subtle change in CRI or R9 values), the use of the most red-shifted garnet in this (by thermal quenching defined) preferred range may be desirable.
[0152] The (minimal) color point CIE u’ of the red phosphor may depend on the required CCT, required color rendering properties and the color point of the green / yellow phosphor. As explained above, in general holds that for a fixed color rendering, the lower the CIE u’ of the red nitride the higher the efficiency, so it makes sense to define the lowest red nitride CIE u’ possible. Allowing all green garnet color points in the analysis (including LuGaAG) results in a minimal CIE u’ of the red phosphor). Selecting only ‘LuAG-type or Y AG-type garnets (i.e. limiting the color point range for the garnet to 0.14-0.19, e.g. achievable using LuAG / YAG or mixtures of the two) may result in a minimal CIE u’ red. Note: CRI>91, R9>55 may not possible with a garnet in the CIE u’ range of 0.14-0.19. In that case the garnet with the highest CIE u’ (close to LuAG) may be selected, i.e. a LuGaAG garnet with minimal gallium doping (to minimize problems with thermal quenching of the garnet).
[0153] In contrast to the desire to maximize the Eu concentration to obtained higher absorption and hence less light scattering losses, it appears that useful phosphor combinations can be made with lower Eu concentrations and optionally lower Sr / Ca ratio’s.
[0154] 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. Unless2025P80074EP01
[0155] 24
[0156] 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.
[0157] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.
[0158] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.
[0159] 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
2025P80074EP0125CLAIMS:
1. A light generating device (1000), configured to generate device light (1001), the light generating device comprising a solid-state light source (10) and a luminescent converter (200), wherein:the solid-state light source (10) is configured to generate source light (11) having a source light peak wavelength (sc) selected from the range of 440 - 475 nm, wherein the solid-state light source (10) is selected from laser diodes;the luminescent converter (200) comprises a first layer (401) and a second layer (402), wherein the first layer (401) comprises a first luminescent material (210), wherein the second layer (402) comprises a second luminescent material (220);the second layer (402) being configured downstream of the first layer (401); the first luminescent material (210) is configured to convert at least part of the source light (11) into first luminescent material light (201), and wherein the second luminescent material (220) is configured to convert at least part of the source light (11) into second luminescent material light (211);the first luminescent material (210) comprises a luminescent material of the type A3B5O12:Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, wherein B comprises one or more of Al, Ga, In and Sc;the second luminescent material (220) comprises a luminescent material of the type MAlSiN3: Eu2+, wherein M comprises one or more of Ba, Sr, and Ca, and wherein the amount of Eu is at most 0.7 mole %;the first luminescent material light (201) has a first chromaticity coordinate ui’ in the CIE u’v’ color diagram in the range of 0.12 < uf < 0.21;the second luminescent material light (211) has a second chromaticity coordinate U2’ in the CIE u’v’ color diagram in the range of 0.34 < U2’ < 0.46; andthe device light (1001) comprises at least part of the first luminescent material light (201), at least part of the second luminescent material light (211), and optionally part of the source light (11).2025P80074EP01262. The light generating device (1000) according to claim 1, wherein A comprises one or more of Y, Gd and Lu, wherein B comprises one or more of Al and Ga.
3. The light generating device (1000) according to claim 1 or 2, wherein M comprises one or more of Ca and Sr; wherein selected from the range of 0.2-0.5 mole% of M consists of Eu; and wherein at least 90 mole % of M consists of one or more of Ca and Sr.
4. The light generating device (1000) according to any one of the preceding claims, wherein:the device light (1001) is white light having a correlated color temperature, CCT, in the range of 1800 - 6500 K and a color rendering index, CRI, of at least 70; and U2’ is selected from the range ((a + b* ui’+ c*CCT +d* CCT2+ e* ui’*CCT + f* ui’*CCT2) - A) <u2’ < ((a + b* ui’+ c*CCT +d* CCT2+ e* ui’*CCT + f* ui’*CCT2) + B), wherein CCT is the correlated color temperature of the device light (1001) in Kelvin, wherein 1*10-3< A < 5*10-3and 1.5*10-2< B < 3*10-2, and wherein the parameters a, b, c, d, e and f are selected from the ranges -3.5*10'2< a < 5.6*10-1, -4.18*10-1< b < 3.42, -9.6*10'5< c < 1.70*10'4, -1.90*10'8< d < 8.49*10'9, -1.56*10’3< e < 4.46*10’4and -3.74*10’8< f < 1.77*10'7.
5. The light generating device (1000) according to any one of the preceding claims, wherein:for (a) a color rendering index of at least 70 and smaller than 75, and (b) an R9 value of at least -40 and smaller than -20, applies that the parameters a, b, c, d, e and f are respectively: -0.035188, 3.42058, 1.69632* IO’04, -1.90922* IO’08, -1.56602* IO’03, and 1.76417*1O'07;for a color rendering index of at least 75 and smaller than 80 and (b) an R9 value of at least -20 and smaller than 0, applies that the parameters a, b, c, d, e and f are respectively: 0.072644, 2.946650, 1.063852* IO’04, -1.276556*10-°8, -1.163253*10-°3, and 1.310682* IO’07;for a color rendering index of at least 80 and smaller than 85 and (b) an R9 value of at least 0 and smaller than 25, applies that the parameters a, b, c, d, e and f are respectively: 0.473403, 8.48705*10-03, -9.06193*10-05, 8.48384*10-09, 3.78497*10-04, and -3.74518*10-08;2025P80074EP0127for a color rendering index of at least 85 and smaller than 90 and (b) an R9 value of at least 25 and smaller than 50, applies that the parameters a, b, c, d, e and f are respectively: 0.394140, 9.21816*1O-01, -3.90425* IO’05, -3.76464E-10, -8.50526*10-°5, and 3.97474*1O'08; andwherein for a color rendering index of at least 90 and (b) an R9 value of at least 50, applies that the parameters a, b, c, d, e and f are respectively: 0.559201, -4.181O4*1O'01, -9.59639*1O'05, 3.83210*10-°9, 4.45205* IO’04, and 0.0.
6. The light generating device (1000) according to any one of the preceding claims, wherein:the device light (1001) is white light having a correlated color temperature, CCT, in the range of 1800 - 6500 K and a color rendering index, CRI, of at least 70; and U2’ is selected from the range (f(CIE ui’,nCCT,nDWL,nCRI,nR9) - A) < U2’ < (f(CIE ui’,nCCT,nDWL,nCRI,nR9) + B), wherein:f(CIE ui’,nCCT,nDWL,nCRI,nR9) = ab+ bb*CIE uf + cb*nCCT + db*nCRI + eb*nDWL + fb*nR9 + gb*(nCCT)2+ hb*(nR9)2+ CIE ul' * [ ib*nCCT +kb*nDWL + lb*nR9]+ nCCT * [mb*nCRI +pb*nDWL + qb*nR9] +rb*nCRI*nR9 + sb*nCCT*(nR9)2nCCT is the value of CCT(K) / 1000; nCRI is the value of CRI / 100; nDWL is the value of DWL / 450, wherein DWL is the value of the dominant wavelength in nanometer of the source light (11); wherein nR9 is the value of R9 / 100; andab= -1.523870; bb= 8.176129; cb= 2.140266*10'1; db= 4.004156*10'1; eb= 1.661350; fb= -1.898141*10'2; gb= 4.200849* 10'3; hb= 1.292229* 10’1; ib= 2.298353*10'1; kb= -8.020100; lb= 8.265873*10'1; mb= -8.556446*10'2; pb= -2.227004* 10’1; qb= 4.439065* 10'2; rb= -1.981058*10'1; and sb= -3.083079*10'2; and wherein 1*10-3< A < 5*10-3and 1.5*10-2< B < 3*10-2.
7. The light generating device (1000) according to any one of claims 4-6, wherein A < 3*10-3and B < 2*10-2.
8. The light generating device (1000) according to any one of the preceding claims, wherein a relation between color point, europium concentration, and fraction of calcium applies:2025P80074EP0128CIE u2’=0.372780 + 0.08200210Log [Eu] + 0.15183 [Ca] + 0.002495*(10Log [Eu])2- 0.06979 [Ca]2wherein [Ca] is the fraction of Ca in the M-site, i.e. between 0 and (1-([Eu] / 100)), and [Eu] is given in mol%, and wherein for values of [Ca] applies that the variation in its fraction is in a range of + / -0.15.
9. The light generating device (1000) according to any one of the preceding claims, wherein the luminescent converter (200) comprises a monolithic body comprising the first luminescent material (210) and the second luminescent material (220).
10. The light generating device (1000) according to any one of the preceding claims, wherein:the first layer (401) comprises one of a (i) ceramic first luminescent material, (ii) single-crystalline first luminescent material or (iii) first matrix material (403) and wherein the first luminescent material (210) comprises first ceramic or single-crystalline luminescent particles being embedded in the first matrix material (403); andthe second layer (402) comprises one of a (i) ceramic second luminescent material, (ii) single-crystalline second luminescent material or (iii) a second matrix material (404) and wherein the second luminescent material (220) comprises second ceramic or single-crystalline luminescent particles being embedded in the second matrix material (404); andthe first matrix material (403) and the second matrix material (404) are independently selected from the group of a polymer material, a ceramic material, and a glass material.
11. The light generating device (1000) according to claim 10, wherein the first layer (401) comprises a ceramic first luminescent material and wherein the second layer (402) comprises a ceramic second luminescent material.
12. The light generating device (1000) according to any one of the preceding claims, wherein the source light peak wavelength (sc) is selected from the range of 440-465 nm; wherein the first luminescent material light (201) has a first chromaticity coordinate uf in the CIE u’v’ color diagram in the range of ui’ < 0.21; and wherein the second luminescent2025P80074EP0129material light (211) has a second chromaticity coordinate U2’ in the CIE u’v’ color diagram in the range of 0.375 < U2’ < 0.44.
13. The light generating device (1000) according to any one of the preceding claims, wherein the solid-state light source (10) comprises a single laser diode, or wherein the light generating device (1000) comprises a plurality of the solid-state light sources (10), wherein each solid-state light source (10) of the plurality of the solid-state light sources (10) comprises a laser diode, wherein the source light peak wavelengths (Xsc) are selected within a range of at maximum 10 nm.
14. The light generating device (1000) according to any one of the preceding claims, wherein the device light (1001) is white light having a correlated color temperature, CCT, in the range of 2700 - 5000 K and a color rendering index, CRI, of at least 70.
15. A lighting system (1200) selected from the group of a lamp (1), a luminaire (2), a lighting fixture, a projector device (3), a stage lighting device, and an automotive lighting device (4), comprising the light generating device (1000) according to any one of the preceding claims 1 - 14.