Tunable light source

Abstract

The invention provides a light generating system (1000) comprising (a) a light generating unit (2000) and (b) a control system (300); wherein: (A) the light generating unit (2000) comprises (i) a first light generating device (110), configured to generate first device light (111), having a first peak wavelength λp1 selected from the 440-490 nm wavelength range, wherein the first light generating device (110) comprises a first solid state light source (10), comprising one or more of a laser diode, a superluminescent diode, and a multi -junction light emitting diode; and (ii) a first luminescent material (210), configured to convert at least part of the first device light (111) into first luminescent material light (211); wherein the light generating unit (2000) is configured to generate unit light (2001) comprising first luminescent material light (211); wherein the first luminescent material (210) comprises M3AlxSi6-xN11-x / 3:Ce3+, wherein M comprises one or more of Sc, Y, La, Gd, Th, and Lu, and wherein x is selected from the range of 0-1; (B) the light generating system (1000) is configured to generate system light (1001) comprising in an operational mode of the light generating system (1000) unit light (2001); and (C) the control system (300) is configured to control a spectral power distribution of the system light (1001) by controlling, in an operational mode of the light generating system (1000), a spectral power distribution of the unit light (2001); wherein the control system (300) is configured to control the spectral power distribution of the unit light (2001) by controlling a temperature of the first luminescent material (210); and wherein the light generating system (1000) is configured such that a CIE u' value of the unit light (2001) is controllable by controlling the temperature of the first luminescent material (211) over a range of at least 0.005.

Description

[0001] 2024PF80402

[0002] 1

[0003] TUNABLE LIGHT SOURCE

[0004] FIELD OF THE INVENTION

[0005] The invention relates to a light generating system and to a lighting device.

[0006] BACKGROUND OF THE INVENTION

[0007] Color tunable light sources are known in the art. US6357889, for instance, describes a color tunable light source including multiple light emitting components, such as light emitting diodes (LEDs) or laser diodes (LDs) with different emission wavelengths, and multiple phosphors with different excitation and emission wavelengths. The emission wavelengths of the different light emitting components are chosen to match the excitation wavelengths of the different phosphors. The light emitting components are powered by an electrical circuit, which allows separate control of the optical power output of the different wavelength LEDs / LDs. By separately adjusting the power to each LED / LD, the amount of light emitted by each phosphor is varied.

[0008] SUMMARY OF THE INVENTION

[0009] Color tunable light sources of the art may be complex and / or include relatively many components. Further, it appears that the use of phosphors may lead to reduced efficiency when operating at high power. For instance, when applying red-shifted Ce-doped garnet phosphors, such as Gd-doped garnets, the garnet emission (to enable lower CCTs) may lead to a strong decrease of the quenching temperature of the phosphor. Hence, such phosphor may not be a feasible solution to achieve lower CCT white light required for illumination and / or when high powers are desired (as then the phosphor may quench).

[0010] 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.

[0011] According to a first aspect, the invention provides a light generating system comprising (a) a light generating unit and (b) a control system. Further, in embodiments the light generating unit may comprise a first light generating device, configured to generate first2024PF80402

[0012] 2

[0013] device light. Especially, the first device light may have a first peak wavelength kpl selected from the 440-490 nm wavelength range. Further, especially the first light generating device may comprises a first solid state light source. In specific embodiments, the first solid state light source may comprise a laser diode. Yet, in embodiments the light generating unit may comprise a first luminescent material. Especially, the first luminescent material may be configured to convert at least part of the first device light into first luminescent material light. Especially, the light generating unit may be configured to generate unit light which may in embodiments comprise first luminescent material light. Further, in embodiments the first luminescent material may comprises M3AlxSi6-xNii-x / 3:Ce3+, wherein M comprises one or more of Sc, Y, La, Gd, Tb, and Lu, and wherein x is selected from the range of 0-1.

[0014] Especially, the light generating system may be configured to generate system light. In embodiments, the system light may comprise, in an operational mode of the light generating system, unit light. Further, in embodiments the control system may be configured to control a spectral power distribution of the system light. Especially, in embodiments the control system may be configured to control a spectral power distribution of the system light by controlling, in an operational mode of the light generating system, a spectral power distribution of the unit light. Further, in embodiments the control system may be configured to control the spectral power distribution of the unit light by controlling a temperature of the first luminescent material. Yet, in embodiments the light generating system may be configured such that a CIE u’ value of the unit light is controllable by controlling the temperature of the first luminescent material over a range of at least 0.005 (and in embodiments a temperature difference of at least 75 °C). Therefore, in embodiments the invention provides a light generating system comprising (a) a light generating unit and (b) a control system; wherein: (A) the light generating unit comprises (i) a first light generating device, configured to generate first device light having a first peak wavelength kp l selected from the 440-490 nm wavelength range, wherein the first light generating device comprises a first solid state light source; wherein the first solid state light source comprises a laser diode; and (ii) a first luminescent material, configured to convert at least part of the first device light into first luminescent material light; wherein the light generating unit is configured to generate unit light which comprises first luminescent material light; (B) the first luminescent material comprises M3AlxSi6-xNn-x / 3:Ce3+, wherein M comprises one or more of Sc, Y, La, Gd, Tb, and Lu; and wherein x is selected from the range of 0-1; (C) the light generating system is configured to generate system light comprising in an operational mode of the light generating system unit light; and (D) the control system is configured to control a spectral power2024PF80402

[0015] 3

[0016] distribution of the system light by controlling, in an operational mode of the light generating system, a spectral power distribution of the unit light; wherein the control system is configured to control the spectral power distribution of the unit light by controlling a temperature of the first luminescent material; and wherein the light generating system is configured such that a CIE u’ value of the unit light is controllable by controlling the temperature of the first luminescent material over a range of at least 0.005 (and a temperature difference of at least 75 °C).

[0017] It appears that, in contrast to the garnet phosphors, these phosphors show a strong color point shift with temperature due to strong self-absorption. However, also a relatively limited decrease of the emission intensity with temperature is observed. Hence, the emission spectrum of the phosphor shifts significantly with temperature in the temperature range where thermal quenching is limited (i.e., quantum efficiency remains high). Especially, the emission of the herein used specific phosphor may red-shift with increasing temperature, due to stronger absorption of the short wavelength emission. Further, relatively low CCT values may be obtained when combining the luminescent material light with blue light.

[0018] Further, the CCT values may be controllable by controlling the temperature of the luminescent material. Hence, amongst others, the invention may provide a CCT tunable laser source. By controlling the phosphor temperature and adjusting the blue-green ratio (separate blue channel or improved reflection of blue from white reflector) a color point shift along the BBL can be achieved. Therefore, with such light generating system, in a relatively simple way light can be generated having a controllable spectral power distribution. Further, a compact lighting solution may be possible in this way.

[0019] As indicated above, the light generating system may comprise (a) a light generating unit and (b) a control system. Especially, the light generating unit may comprise a first light generating device and a first luminescent material. Here below, some general aspects in relation to light generating devices and light sources are described.

[0020] Note that the term “light generating device” may also refer to a plurality of (essentially) identical light generating devices. Especially, (essentially) identical light generating devices may provide light with (essentially) identical spectral power distributions under (essentially) identical operation conditions. Any light generating device may comprise a light source. Hence, a light generating device may also comprise a plurality of light sources. In a specific embodiment, the light source may comprise a solid state light source. Hence, especially herein the term “light source” refers to a solid state light source. Herein, the terms “solid state light source”, “semiconductor-based light source”, or “solid state material light2024PF80402

[0021] 4

[0022] source”, may all refer to semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), polymer light-emitting diodes (PLEDs), laser diodes (or “diode lasers”), superluminescent diodes (SLEDSs), stacked multi -junction light emitting diode, etc. Hence, the term “light source” may herein refer to a semiconductor light-emitting device, such as a light emitting diode (LED), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term “light source” may herein also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). The term “light source” may herein also refer to a superluminescent diode (SLED). Suitable solid state light sources or semiconductor-based light sources, such as LEDs, may be selected from (III-V compound) semiconductors, such as in specific embodiments semiconductors selected from the group of GaN, AlGaN, InGaN, and AlGalnN, (especially for blue-green), GaP, InP, GalnP, and AlGalnP (especially for red-NIR), GaAs, AlGaAs, InGaAs, and InGaAsP (especially for NIR-MIR). Hence, in embodiments herein a light source may comprise a semiconductor selected from the group of GaN, AlGaN, InGaN, AlGalnN, GaP, InP, GalnP, and AlGalnP. Hence, in embodiments the term “light source” may herein refer solid state light sources that are not organic material based, like OLEDs.

[0023] The term “light source” may also 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.

[0024] 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. The term LED may also refer to a plurality of LEDs. 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.

[0025] 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 wavelength bin.2024PF80402

[0026] 5

[0027] 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” or “direct LEDs”.

[0028] Especially, a light source may be configured to generate light source light (during operation of the light source). A light generating device may be configured to generate device light (during operation of the light generating device).

[0029] When the light generating device comprises a direct LED only, the device light may consist of the light source light. Optionally, the light generating device may comprise optics, such as micro optical elements. The optics may be configured to beam shape the light source light (into a beam of device light). 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. The light generating device may also comprise a plurality of solid-state light sources and one or more micro-optical elements (array of micro lenses) downstream of the plurality of solid-state light sources. In embodiments, the light generating device may comprise an LED with on-chip optics. In embodiments, the light generating device may comprise pixelated single LEDs (with or without optics) (offering in embodiments on-chip beam steering). When a light generating device comprises a plurality of solid state light sources, they may in embodiments be from the same wavelength bin, though this is not necessarily the case. In embodiments, the light generating device may comprise LED array or a laser bank. Especially, herein the term “solid state light source” may refer to a LED, a laser diode, a super luminescent diode, a (stacked) multi -junction diode, a VCSELs (vertical -cavity surface-emitting laser), etc. Hence, in embodiments, the light source may comprise an LED (light emitting diode). In other embodiments, herein the light source may comprise a laser diode.

[0030] Especially, herein the first light generating device comprises a first solid state light source. In specific embodiments, the first solid state light source may be selected from the group of a laser diode, a superluminescent diode, and a (stacked) multi -junction light emitting diode. More especially, in embodiments the first solid state light source comprises a laser diode. Herein, the invention is especially described in relation to embodiments wherein the first solid state light source comprises a laser diode. As the solid state light source may comprise a laser diode, the light of the first light source, herein also indicated as first light source light, may be laser light. More especially, the light generated by the first light2024PF80402

[0031] 6

[0032] generating device may comprise the first light source light (more especially the laser light). Yet, in embodiments the light generated by the first light generating device consists of the first light source light, more especially the laser light.

[0033] Further, in embodiments the first light generating device may be configured to generate first device light, especially having a first peak wavelength kpl . Especially, in embodiments the first peak wavelength kp l may be elected from the wavelength range of 430-490 nm, more especially selected from the 440-490 nm wavelength range. Yet, in specific embodiments the first peak wavelength kpl of the first device light may be elected from the wavelength range of 440-470 nm, more especially from the wavelength range of 440-460 nm.

[0034] As indicated above, the light generating unit may further comprise the first luminescent material. Here below, some information in general in relation to luminescent materials is provided.

[0035] The term “luminescent material” may especially refer to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation, especially having a wavelength in the visible wavelength range in case of lighting applications. In general, the first radiation and second radiation have different spectral power distributions. 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. Instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” or “luminescent converter material” may be applied. Instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art. In embodiments, 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. The luminescent material is especially configured to convert light of a source of light, like the light source as mentioned above or the light generating as mentioned above, into luminescent material light. The term “luminescent material” may also refer to a plurality of different luminescent materials. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition.2024PF80402

[0036] 7

[0037] Herein, in embodiments, the first luminescent material may especially be configured to convert at least part of the first device light into first luminescent material light. As further elucidated below, in embodiments this may be a partial conversion, and in other embodiments this may be an essentially full conversion. The first light generating device (or the first light source) may therefore also be indicated as “pump” or “pump light source”, and the first device light (or first light source light) may be indicated as “excitation light”.

[0038] In embodiments, the first luminescent material may comprise MsAlxSie-xNn-x / 3:Ce3+, wherein M comprises one or more of Sc, Y, La, Gd, Tb, and Lu, and wherein x is selected from the range of 0-1.

[0039] 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= Sc, Y, La, Gd, Tb, Lu (herein indicated as “one or more of Sc, Y, La, Gd, Tb, and Lu”), then n=6, this may imply that M3AlxSi6-xNii-x / 3:Ce3+may also be written as (ScsYyLaiaGdgTbtLuiuCec)3AlxSi6-xNn-x / 3, wherein (s+y+la+g+t+lu+c)=l, wherein especially c is selected from the range of 0.001-0.1. Further, each of s, y, la, g, t, and lu may be zero, larger than zero, but not larger than (1-c). Especially, (s+y+la)>(g+t+lu). Especially, in embodiments (y+la+c)>0.9. Hence, in specific embodiments M comprises one or more of Y and La.

[0040] In embodiments, at least 90 vol.%, more especially at least 95 vol.%, such as 100 vol.% of the first luminescent material is M3AlxSi6-xNn-x / 3:Ce3+.

[0041] In embodiments, x may thus be selected from the range of 0-1. For instance, in embodiments x may be selected from the range of 0-0.2, such as selected from the range of 0-0.1 (like e.g. up to about 0.05). In (specific) embodiments, x=0. Hence, in specific embodiments the first luminescent material may comprise NLSieNiuCe3, wherein M comprises one or more of Sc, Y, La, Gd, Tb, and Lu. Especially, as indicated above, M may comprise one or more of Y and La.

[0042] Further, in embodiments the light generating unit may especially be configured to generate unit light which comprises first luminescent material light. When there is no full conversion, the unit light may also comprise first device light; see further also below.

[0043] The first luminescent material may be in physical contact with the first light generating device, or may be configured remote therefrom. Especially, however, any visible light escaping from the light generating unit may escape via the first luminescent material.2024PF80402

[0044] 8

[0045] Further, especially, the light generating system is configured to generate system light. Would the light generating system comprise as only source of light the light generating unit, then the system light may essentially consist of the unit light. However, would the light generating system comprise another source of light, the system light may comprise light from the other source of light and / or unit light. Hence, in embodiments the light generating system may be configured to generate system light comprising in an operational mode of the light generating system unit light. In embodiments, this may thus be the only operational mode, whereas in other embodiments, there may be more than one operational mode; see also below.

[0046] As the first luminescent material shows a temperature dependent spectral power distributions, or more precisely, a temperature dependent color point shift, whereas quantum efficiency over a substantial temperature range stays substantially constant, the control system can control the spectral power distribution of the system light by controlling the temperature of the first luminescent material (and optionally by controlling further light sources).

[0047] Hence, in embodiments, the control system may be configured to control a spectral power distribution of the system light by controlling, in an operational mode of the light generating system, a spectral power distribution of the unit light. Yet, in specific embodiments the control system may be configured to control the spectral power distribution of the unit light by controlling a temperature of the first luminescent material. For instance, it may be possible to control in this way the unit light from white light having a higher CCT (at lower temperatures of the first luminescent material) to white light having a lower CCT (at higher temperatures of the first luminescent material). Or, it may be possible to control in this way the unit light from more greenish light (at lower temperatures of the first luminescent material) to more orange-like light (at higher temperatures of the first luminescent material). By controlling the temperature, especially the u’ value of the unit light may be controlled. In specific embodiments, the light generating system may be configured such that a CIE u’ value of the unit light may be controllable by controlling the temperature of the first luminescent material over a range of at least 0.005. In embodiments, this may imply a temperature difference of at least 75 °C. For instance, it may even be possible to control a CIE u’ value of the unit light by controlling the temperature of the first luminescent material over a range of up to about 0.02 when applying temperature difference up to about 175°.

[0048] The term “operational mode” especially refers to a way in which a (light) source, device, or system operates. For instance, when a device, source, of system can only2024PF80402

[0049] 9

[0050] execute a single action, (e.g. generating white light), then there may be a single operational mode. However, would the (light) source, device, or system be controllable (e.g. generating white light or colored light, in dependence of controllable settings), the (light) source, device, or system may have different operational modes.

[0051] The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface. The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system. Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. In such embodiments the control system of the lighting system may be a slave control system or control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system which has access to the lighting system on the basis of knowledge (input by a user interface of with an optical sensor (e.g. QR code reader) of the (unique) code. The lighting system may also comprise means for communicating with other systems or devices, such as on the basis of Bluetooth, Thread, WIFI, LiFi, ZigBee, BLE or WiMAX, or another wireless technology.2024PF80402

[0052] 10

[0053] The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or “mode of operation” or “operational mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed.

[0054] However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability).

[0055] Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and / or a predetermined time scheme.

[0056] Amongst others, it appears that controlling the phosphor temperature can be done by adjustment of the rotation speed of the phosphor wheel, by adjusting the heat sink temperature (static phosphor)(e.g. by decreasing the speed of cooling fans) and / or adjustment of the PWM scheme (short pulses with high intensity versus longer pulses with lower max intensity). This can be used to a) achieve a high-brightness white light source with good color quality (deliberately elevate the temperature to a certain level and keep it there) or b) a color-tunable high-brightness white light source (change the color temperature during use).

[0057] Assuming e.g. a pulsed laser diode, for instance for heating the pulse height (=current) may be increased, and optionally also the pulse width may be increased when an even higher brightness is needed.

[0058] Hence, in embodiments the first light generating device may comprise a pulsed first solid state light source, and wherein the control system may be configured to control the temperature of the first luminescent material by controlling one or more of pulse width, pulse height, and pulse frequency of the first device light.

[0059] Additionally or alternatively, the temperature of the phosphor may be controlled by controlling the temperature of a phosphor support. Hence, in embodiments, the light generating system may (further) comprise a first luminescent material support2024PF80402

[0060] 11

[0061] configured to support the first luminescent material, and wherein the control system may be configured to control the temperature of the first luminescent material by controlling a temperature of the first luminescent material support.

[0062] Additionally or alternatively, the temperature of the phosphor may be controlled by controlling a rotational speed or rotational frequency of a phosphor wheel comprising the first luminescent material. Phosphor wheels are known in the art. The first luminescent material may be configured on the phosphor wheel or may be comprised in a recess in the phosphor wheel, etc. Hence, in embodiments the light generating system may (further) comprise a rotatable element, wherein the first luminescent material is comprised by the rotatable element, and wherein the control system is configured to control the temperature of the first luminescent material by controlling a rotational frequency of the rotatable element.

[0063] Optionally, or additionally, in embodiments, control of the temperature of the first luminescent material may be executed with one or more of (a) providing IR radiation to the first luminescent material and / or to the first luminescent material support (for heating), (b) providing a flow of a gas, such as air, to the first luminescent material and / or to the first luminescent material support (for heating or cooling). Further, in embodiments control of the temperature of the first luminescent material may be executed with controlling one or more of a fan speed (air cooled system) and water pumping speed (water cooled system). A fan may cool the first luminescent material and / or the first luminescent material support. A water cooled system may be used to control temperature of the first luminescent material support.

[0064] Controlling the temperature may include heating or cooling. Further, in embodiments the light generating system may (further) comprise a temperature control element configured to heat or cool the first luminescent material (directly or indirectly). In such embodiments, the control system may be configured to control the temperature control element.

[0065] Further, in embodiments the light generating system may be configured such that the temperature of the first luminescent material is controllable over a range of at least 125 °C. This may allow a change in u’ of in the order of 0.01 or larger.

[0066] In embodiments, the lowest operation temperature of the first luminescent material may especially be selected from the range of 15-30 °C. Hence, in embodiments the control system may be configured to maintain the temperature of the first luminescent material at at least 15 °C. Further, in embodiments the control system may especially be configured to maintain the temperature of the first luminescent material below 300 °C, more2024PF80402

[0067] 12

[0068] especially below 275 °C, like in specific embodiments below 250 °C. At higher temperatures, the quantum efficiency may drop too much. Up to about 300 °C, the drop may be acceptable, and up to about 250 °C, the drop in quantum efficiency may only be a few percent. At 250 °C, the QE drop may be at maximum about 10%, and at 300 °C, the QE drop may be at maximum about 20%.

[0069] In specific embodiments, the light generating system may be configured such that a CIE u’ value of the unit light is controllable by controlling the temperature of the first luminescent material over a range of at least 0.01 (and a temperature difference of at least 75 °C). For instance, in embodiments the light generating system may be configured such that a CIE u’ value of the unit light is controllable by controlling the temperature of the first luminescent material over a range of at least 0.005 and / or a temperature difference of at least 125 °C. For instance, in embodiments the light generating system may be configured such that a CIE u’ value of the unit light is controllable by controlling the temperature of the first luminescent material over a range of at least 0.008.

[0070] In embodiments, the first luminescent material light has a first centroid wavelength Xci. Further, in embodiments the first centroid wavelength Xci may be controllable over a range of at least about 15 nm. Dependent also on the luminescent material composition, the thickness of the luminescent material layer, and the temperature of the luminescent material, the first centroid wavelength Xci may be controllable between about 570 nm and 630 nm.

[0071] Further, in embodiments the unit light may comprise both the first luminescent material light and the first device light. In such embodiments, the unit light may have a unit light centroid wavelength Xc,ui. Yet, in embodiments the unit light centroid wavelength Xc,uimay be controllable between about 545 nm and 595 nm, in dependence of its temperature. This may in embodiments allow a CCT range of about 5500 K to 2600 K.

[0072] The term “centroid wavelength”, also indicated as c, is known in the art, and refers to the wavelength value where half of the light energy is at shorter and half the energy is at longer wavelengths; the value is stated in nanometers (nm). It is the wavelength that divides the integral of a spectral power distribution into two equal parts as expressed by the formula Ac = X I(k) / (S I( A)), where the summation is over the wavelength range of interest, and I (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.2024PF80402

[0073] 13

[0074] As indicated above, in embodiments the first luminescent material may be configured in the transmissive mode. Herein, the term “transmissive mode” may refer to an arrangement wherein light source light at one side of the luminescent material (or luminescent element comprising the luminescent material) is provided and at another side of the luminescent material (or luminescent element comprising the luminescent material) light escapes therefrom and may end up in the system light of the light generating system. Hence, the luminescent material (or luminescent element comprising the luminescent material) may have a thickness which may bridge the one side and the other side. Further, the light that escapes at the other side of the luminescent material (or luminescent element comprising the luminescent material) may comprise luminescent material light and optionally light source light (of the pump or excitation light source). In a full conversion mode, there may essentially be no light source light (of the pump or excitation light source).

[0075] In other embodiments, however, the first luminescent material may be configured in the reflective mode. When a luminescent material is configured in the reflective mode, the luminescent material may be irradiated from one side with (excitation) light, which is at least partly be converted by the luminescent material into luminescent material light, and the luminescent material light escaping from that same side may be used (further) in the light generating system or light generating device. Optionally, non-converted (excitation) light may also escape from the other side (e.g. due to surface or bulk reflection by the luminescent material). The luminescent material may be comprised by a layer or element, such as a plate, having to main essentially parallel faces, of which one may receive the (excitation) light.

[0076] In the transmissive mode, the first luminescent material may in embodiments be in physical contact with the first solid state light source, such as a laser diode. However, the first luminescent material may also be configured remove from the first solid state light source, such as in specific embodiments at a distance of at least 100 pm.

[0077] In the reflective mode, the first luminescent material may be configured at some distance of the first solid state light source, such as in specific embodiments at a distance of at least 100 pm.

[0078] When in embodiments the first luminescent material is configured at some distance of the first solid state light source, in specific embodiments, the first luminescent material may be comprised by a phosphor wheel.

[0079] In embodiments, the unit light emanating from the light generating unit, during operation thereof, may comprise some first device light (“pump light”) . Especially, in embodiments this may be blue light. In this way white unit light may be generated (see also2024PF80402

[0080] 14

[0081] below). Hence, in embodiments the light generating unit may be configured to generate unit light having a spectral power distribution in the wavelength range of 380-780 nm, wherein selected from the range of 0.25-25% of the spectral power is in the 380-490 nm wavelength range (and provided by the first light generating device). When assuming blue first device light, at about 25%, the CCT of the unit light may be about 6500 K; at low percentage of first device light in the spectral power distribution of the unit light, the CCT may be in the order of 2700 K.

[0082] In embodiments, the lighting unit light may have a CCT selected from the range of 2600-6500 K, such as in embodiments at least about 2700 K, like in specific embodiments selected from the range of 3000-6000 K.

[0083] In other embodiments, however, such as in the full conversion mode, the contribution of the first device light may essentially be zero. Hence, in (other) embodiments, less than 0.2% (such as at maximum 0.05%) of the spectral power is in the 380-490 nm wavelength range. Therefore, in embodiments the light generating unit may be configured to generate unit light having a spectral power distribution in the wavelength range of 380-780 nm, wherein selected from the range of less than 0.2% (such as at maximum 0.05%) of the spectral power (of the unit light) is in the 380-490 nm wavelength range (and provided by the first light generating device).

[0084] As indicated above, the light generating system may in embodiments comprise the light generating unit as only source for the system light. This would allow generating color controllable (about greenish-orange-like light) or white light, having controllable spectral power distributions. However, the light generating system may in other embodiments comprise a further source of light. In this way, the spectral power distribution of the system light may further be controlled.

[0085] Hence, in embodiments the light generating system may further comprise a second light generating device. In specific embodiments, the term “second light generating device” may in embodiments refer to a plurality of second light generating devices which provide second device light having essentially the same spectral power distributions, but may in other embodiments refer to two or more subsets of light generating devices, with each subset comprising one or more light generating devices which provide device light having essentially the same spectral power distributions, but wherein the spectral power distributions of device light of light generating devices of different subsets differ. Especially, the second light generating device is configured to generate second device light having a second centroid wavelength Zc2. Further, in embodiments the second light generating device may comprises a2024PF80402

[0086] 15

[0087] second solid state light source. For solid state light sources and light generating devices in general, it is referred to above.

[0088] In specific embodiments, colors or color points of a first type of light and a second type of light may be different when the respective color points of the first type of light and the second type of light differ with at least 0.01 for u’ and / or with at least 0.01 for v’, even more especially at least 0.02 for u’ and / or with at least 0.02 for v’. In yet more specific embodiments, the respective color points of first type of light and the second type of light may differ with at least 0.03 for u’ and / or with at least 0.03 for v’. Spectral power distributions of different sources of light having centroid wavelengths differing at least 10 nm, such as at least 20 nm, or even at least 30 nm may be considered different spectral power distributions, e.g. different colors. In general, the differences in centroid wavelengths will not be larger than about 400 nm, such as not more than 350 nm. In other specific embodiments, colors or color points of a first type of light and a second type of light may be essentially the same when the respective color points of the first type of light and the second type of light differ with at maximum 0.03 for u’ and / or with at maximum 0.03 for v’, even more especially at maximum 0.02 for u’ and / or with at maximum 0.02 for v’. In yet more specific embodiments, the respective color points of first type of light and the second type of light may differ with at maximum 0.01 for u’ and / or with at maximum 0.01 for v’.

[0089] Herein, u’ and v’ are color coordinates of the light in the CIE 1976 UCS (uniform chromaticity scale) diagram (CIE 1976 color points (see ISO CIE 11664-5:

[0090] Colorimetry - Part5: CIE 1976 L*u*v* color space and u', v' uniform chromaticity scale diagram).

[0091] Especially, the light of the further source of light may spectrally differ from the first luminescent material light. Hence, in embodiments | Xc2-Xcl|> 10 nm, more especially | Xc2-Xcl|> 20 nm. Likewise, this may apply to optional further light generating devices.

[0092] Alternatively or additionally, the light of the further source of light may spectrally differ from the unit light centroid wavelength Xc,ui. Hence, in embodiments | Ac2-Xc,ui |> 10 nm, more especially | Ac2- Xc,ui|> 20 nm. Likewise, this may apply to optional further light generating devices. Hence, in embodiments the light generating system may comprise the light generating unit which may be configured to generate white unit light, and e.g. a second light generating device configured to generate red second device light. The system light may comprise one or more of the unit light and second device light, and the spectral power distribution of the system light may be controlled.2024PF80402

[0093] 16

[0094] In embodiments the light generating system may be configured such that a CIE u’ value of the unit light is selected from the range of 0.08-0.28, more specially selected from the range of 0.19-0.28. Further, in such embodiments, especially the second centroid wavelength Xc2 may be selected from the wavelength range of 560-680 nm, though other options may also be possible.

[0095] In other embodiments, the light generating system may comprise the light generating unit which may be configured to generate greenish or yellows unit light, and e.g. a second light generating device configured to generate red second device light and / or a third light generating device configured to generate blue device light. The system light may comprise one or more of the unit light, the second device light, and the third device light, and the spectral power distribution of the system light may be controlled. Especially, the third light generating device is configured to generate third device light having a third centroid wavelength Xc3. Further, in embodiments the third light generating device may comprises a third solid state light source. For solid state light sources and light generating devices in general, it is referred to above. In specific embodiments, the light generating system may further comprise a third light generating device, wherein the third light generating device is configured to generate third device light having a third centroid wavelength Xc3; wherein the third light generating device comprises a third solid state light source; wherein | Xc3-Xcl|> 20 nm, and wherein the third centroid wavelength Xc3 is selected from the wavelength range of 430-490 nm (especially selected from the wavelength range of 440-490 nm). The third light generating device may thus be a source of blueish light, especially blue light.

[0096] Hence, in embodiments the light generating system may be configured such that a CIE u’ value of the unit light is selected from the range of 0.08-0.28, more specially selected from the range of 0.19-0.28, wherein the light generating system may further comprise a second light generating device (wherein the second light generating device is configured to generate second device light having a second centroid wavelength Xc2, wherein the second light generating device comprises a second solid state light source, wherein | Xc2-Xcl |> 20 nm), the light generating system may further comprise a third light generating device (wherein the third light generating device is configured to generate third device light having a third centroid wavelength Xc3, wherein the third light generating device comprises a third solid state light source; wherein | Xc3-Xcl|> 20 nm), wherein the second centroid wavelength Xc2 may be selected from the wavelength range of 560-680 nm, and wherein third centroid wavelength Xc3 may be selected from the wavelength range of 430-490 nm (more especially selected from the wavelength range of 440-490 nm.2024PF80402

[0097] 17

[0098] In embodiments, the light generating system may also comprise a fourth light generating device. The fourth light generating device may be configured to generate white fourth device light. In this way, the CCT of the system may e.g. further be controlled.

[0099] One or more of the second light generating device, third light generating device, and fourth light generating device, may also comprise a luminescent material, such luminescent material may be different from the first luminescent material (though this is not necessarily the case). To distinguish possible luminescent material, the luminescent material comprised by the light generating unit may be indicated as “first luminescent material” (and any luminescent material external therefrom, may be indicated as “second luminescent material”).

[0100] In specific embodiments, the system light is, may in an operational mode of the light generating system, be white system light, wherein a correlated color temperature of the white system light is controllable by controlling the temperature of the first luminescent material, wherein the light generating system is configured such that the correlated color temperature of the white system light is controllable over a range of at least 200 K, such as at least 500 K, like in embodiments at least about 750 K. As indicated above, in some embodiments the system light may essentially consist of the unit light. In such embodiments, the CCT may essentially only be controlled by the temperature of the first luminescent material. However, when the light generating system further comprises one or more further light generating devices (second light generating device and / or third light generating device), then the spectral power distribution of the system light may be controlled by controlling by the temperature of the first luminescent material and / or by controlling the one or more further light generating devices.

[0101] 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, greenhouse 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.2024PF80402

[0102] 18

[0103] 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.

[0104] 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. 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 620-780 nm, such as 620-750 nm. In specific embodiments, the red light may have a centroid wavelength2024PF80402

[0105] 19

[0106] in the 620-780 nm range, such as 620-750 nm. 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.

[0107] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc... The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support one or more of light generating unit and the control system.

[0108] In yet a further aspect, the invention also provides a lighting fixture comprising the light generating system as defined herein. Hence, in yet a further aspect, the light generating 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 elements of the light generating system, such as the light generating unit, and the2024PF80402

[0109] 20

[0110] light generating system may further comprise e.g. a control system configured to control the device. 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. In embodiments, the lamp or luminaire may be a downlighter or an uplighter. In embodiments, the lamp may comprise a torch. Hence, amongst others the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a lighting fixture, comprising the light generating system as described herein.

[0111] BRIEF DESCRIPTION OF THE DRAWINGS

[0112] 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:

[0113] Fig. 1 schematically depicts possible embodiments of the light generating system;

[0114] Figs. 2a-2b schematically depicts some embodiments in relation to temperature control;

[0115] Fig. 3 schematically depicts a further embodiment;

[0116] Fig. 4 shows the range of color points that can be achieved; and Fig. 5 schematically depicts some application embodiments.

[0117] The schematic drawings are not necessarily to scale.

[0118] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0119] Fig. 1 schematically depicts possible embodiments of the light generating system 1000. However, other embodiments may also be possible. In specific embodiments, the invention provides a light generating system 1000 comprising (a) a light generating unit 2000 and (b) a control system 300. Further, in embodiments, the light generating unit 2000 may comprise (i) a first light generating device 110, configured to generate first device light 111 having a first peak wavelength kpl selected from the 440-490 nm wavelength range. In further embodiments, the first light generating device 110 may comprise a first solid state2024PF80402

[0120] 21

[0121] light source 10. The solid state light source 10 may comprise one or more of a laser diode, a superluminescent diode, and a stacked multi -junction light emitting diode. Moreover, in embodiments, the first solid state light source 10 may comprise a laser diode. Further, the light generating unit 2000 may comprise (ii) a first luminescent material 210, configured to convert at least part of the first device light 111 into first luminescent material light 211. Especially, the light generating unit 2000 may be configured to generate unit light 2001 which may comprise first luminescent material light 211. In further embodiments, the first luminescent material 210 may comprise M3AlxSi6-xNii-x / 3:Ce3+, and wherein x is selected from the range of 0-1. Further, in embodiments, M may comprise one or more of Sc, Y, La, Gd, Tb, and Lu. Yet, in embodiments, the light generating system 1000 may be configured to generate system light 1001 comprising in an operational mode of the light generating system 1000 unit light 2001. Further, in embodiments, the control system 300 may be configured to control a spectral power distribution of the system light 1001 by controlling, in an operational mode of the light generating system 1000, a spectral power distribution of the unit light 2001. In specific embodiments, the control system 300 may be configured to control the spectral power distribution of the unit light 2001 by controlling a temperature of the first luminescent material 210. In further embodiments, the light generating system 1000 may be configured such that a CIE u’ value of the unit light 2001 may be controllable by controlling the temperature of the first luminescent material 211 over a range of at least 0.005 (and a temperature difference of at least 75 °C). Controlling the phosphor temperature can be done by adjustment of the rotation speed of the phosphor wheel, by adjusting the heat sink temperature (static phosphor) and / or adjustment of the PWM scheme (short pulses with high intensity versus longer pulses with lower max intensity). This can be used to a) achieve a high-brightness white light source with good color quality (deliberately elevate the temperature to a certain level and keep it there) or b) a color-tunable high-brightness white light source (change the color temperature during use. Would a laser diode be operated nonpulsed, then the temperature may be lowest.

[0122] The dashed element in Fig. 1 is an optional optical filter. Further, more optical elements may be available than depicted. This will be known to a person skilled in the art.

[0123] In embodiments, the first light generating device 110 may comprise a pulsed first solid state light source 10. In further embodiments, the control system 300 may be configured to control the temperature of the first luminescent material 210 by controlling one or more of pulse width, pulse height, and pulse frequency of the first device light 111.2024PF80402

[0124] 22

[0125] Referring to e.g. also Figs. 2a-2b, the light generating system 1000 may comprise a first luminescent material support 710 configured to support the first luminescent material 210.

[0126] In embodiments, the control system 300 may be configured to control the temperature of the first luminescent material 210 by controlling a temperature of the first luminescent material support 710.

[0127] Referring to Fig. 2b, in embodiments, the light generating system 1000 may may comprise a rotatable element 1260. In specific embodiments, the first luminescent material 210 may be comprised by the rotatable element. In further embodiments, the control system 300 may be configured to control the temperature of the first luminescent material 210 by controlling a rotational frequency of the rotatable element 1260.

[0128] Moreover, in embodiments, the light generating system 1000 may further comprise a temperature control element 1260 configured to heat or cool the first luminescent material 210 (directly or indirectly). Furthermore, in embodiments, the control system 300 may be configured to control the temperature control element 1260.

[0129] In specific embodiments, the light generating system 1000 may be configured such that the temperature of the first luminescent material 211 may be controllable over a range of at least 125 °C. Yet, especially, the control system 300 may be configured to maintain the temperature of the first luminescent material 211 below 250 °C.

[0130] The first luminescent material 210 is especially configured downstream of the first light generating device 110; the latter may thus be configured upstream of the former. 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”.

[0131] Referring to Fig. 1, embodiment I, or Fig. 2a, embodiment I, in embodiments, the first luminescent material 210 may be configured in the transmissive mode. Referring to Fig. 1, embodiment II, Fig. 2a, embodiments II and III, or to Fig. 2b, in embodiments, the first luminescent material 210 may be configured in the reflective mode.

[0132] Especially, in embodiments, the light generating unit 2000 may be configured to generate unit light 2001 having a spectral power distribution in the wavelength range of 380-780 nm. Moreover, in embodiments, selected from the range of 0.25-25% of the spectral2024PF80402

[0133] 23

[0134] power may be in the 380-490 nm wavelength range (and provided by the first light generating device 110). In other embodiments, however, less than 0.2% of the spectral power may be in the 380-490 nm wavelength range.

[0135] Especially, the first luminescent material light 211 may have a first centroid wavelength Xcl.

[0136] Referring to e.g. Fig. 3, in embodiments, the light generating system 1000 may further comprise a second light generating device 120. Further, in embodiments, the second light generating device 120 may be configured to generate second device light 121 having a second centroid wavelength Xc2. Moreover, in embodiments, the second light generating device 120 may comprise a second solid state light source 20. In further embodiments, | Xc2-Xcl |> 20 nm.

[0137] In further embodiments, the light generating system 1000 may further comprise a third light generating device 130. Furthermore, in embodiments, the third light generating device 130 may be configured to generate third device light 131 having a third centroid wavelength Xc3. Especially, the third light generating device 130 may comprise a third solid state light source 30. Further, in embodiments, | Xc3-Xcl|> 20 nm. Especially, the light generating system 1000 may be configured such that a CIE u’ value of the unit light 2001 may be selected from the range of 0.08-0.28. Especially, the light generating system 1000 may be configured such that a CIE u’ value of the unit light 2001 may be selected from the range of 0.19-0.28. Further, in embodiments, the second centroid wavelength Xc2 may be selected from the wavelength range of 560-680 nm, and third centroid wavelength Xc3 may be selected from the wavelength range of 430-490 nm (especially selected from the wavelength range of 440-490 nm).

[0138] In Fig. 2b, reference 520 refers to a dichroic element, which may reflect first luminescent material light 211, but transmit first device light 111 (other way around may also be possible, but then another configuration should be chosen).

[0139] Fig. 3 schematically depicts an embodiment of an LED package. Here also, by way of example a fourth light generating device 140, configured to generate fourth device light 141 is depicted. Such fourth light generating device 140 may e.g. be applied as source of white fourth device light 141, would the light generating unit 2000 be configured to generate greenish / yellows light. In this way, different types of white system light 1001 may be provided.

[0140] Fig. 3 schematically depicts a LED package. However, other embodiments, with e.g. light generating devices 120,130,140 separately configured from the light2024PF80402

[0141] 24

[0142] generating unit 2000 may also be possible. Further, in embodiments especially, the solid state light sources 20,30,40 may in embodiments be laser diodes. Further, also the first solid state light source 10 may be a laser diode in embodiments.

[0143] Furthermore, in embodiments, the light generating system 1000 wherein the system light 1001 is, in an operational mode of the light generating system 1000, white system light 1001. Moreover, in embodiments, a correlated color temperature of the white system light 1001 may be controllable by controlling the temperature of the first luminescent material 211. Moreover, in embodiments, the light generating system 1000 may be configured such that the correlated color temperature of the white system light 1001 may be controllable over a range of at least 500 K.

[0144] The light generating system 1000 as schematically depicted herein may comprise further optics, which are not depicted herein. The term “optics” may especially refer to (one or more) optical elements. Hence, the terms “optics” and “optical elements” may refer to the same items. The optics may include one or more or mirrors, reflectors, collimators, lenses, prisms, diffusers, phase plates, polarizers, diffractive elements, gratings, dichroics, arrays of one or more of the afore-mentioned, etc. Alternatively or additionally, the term “optics” may refer to a holographic element or a mixing rod. In embodiments, the optics may include one or more of beam expander optics and zoom lens optics. In embodiments, the optics may comprise an integrator, like a “Koehler integrator” (or “Kohler integrator”).

[0145] Further, for two luminescent material slabs the CCT of the light provided in the transmissive mode was controlled by controlling the temperature (see also Fig. 4):

[0146] Temperature (°C) u’ v’

[0147] 30 0.2043 0.5652

[0148] 50 0.2053 0.5650

[0149] 100 0.2080 0.5647

[0150] 150 0.2112 0.5643

[0151] 200 0.2144 0.5641

[0152]

[0153] 2024PF80402

[0154] 25

[0155] Temperature (°C) u’ v’

[0156] 30 0.2190 0.5651

[0157] 50 0.2212 0.5649

[0158] 100 0.2277 0.5642

[0159] 150 0.2348 0.5633

[0160] 200 0.2424 0.5623

[0161]

[0162] Yet, in below table some examples are provided. In the table, u’ as a function of temperature for different phosphor slabs have been given. Different columns represent different thicknesses, with “0%” indicating full conversion and “62%” indicating partial conversion with about 62% of the spectral power in the blue.

[0163] T (°C) 0% Blue 0.3% Blue 62% Blue

[0164] 25 0.2286 0.2182 0.2038

[0165] 45 0.2317 0.2206 0.2050

[0166] 65 0.2351 0.2231 0.2060

[0167] 85 0.2385 0.2258 0.2072

[0168] 105 0.2420 0.2284 0.2083

[0169] 125 0.2456 0.2312 0.2096

[0170] 145 0.2493 0.2342 0.2109

[0171] 165 0.2534 0.2370 0.2121

[0172] 185 0.2574 0.2401 0.2133

[0173] 205 0.2615 0.2431 0.2147

[0174] 225 0.2657 0.2464 0.2161

[0175] 245 0.2701 0.2497 0.2173

[0176]

[0177] In a further experiment, with a blue laser, the temperature of the first luminescent material was increased. The CCT and centroid wavelength (CWL) are indicated below, with from left to light an increase of the temperature of the first luminescent material.2024PF80402

[0178] 26

[0179] %blue 23% 20% 17% 15% 13% 11% 9% CCT (K) 4545 4031 3690 3387 3117 2880 2646 CWL (nm) 557 564 569 575 581 587 593

[0180]

[0181] In yet an example, it was possible to decrease the CCT of the unit light from 4000 to 2700K (by controlling the intensity of the first device light). The blue contribution to the visible wavelength range decreased from 20% to 10% (white color point on BBL).

[0182] Further, the centroid wavelength of the white spectrum increases from 561 nm to 586 nm. The centroid wavelength of the (green) phosphor increased from 589 to 603 nm.

[0183] As indicated above, in embodiments the unit light 2001 may be white light (with some blue spectral power, from the first light generating device), whereas in other embodiments, the unit light may be colored light (with substantially no blue spectral power).

[0184] Experimental results showed that the thermal quenching of the first luminescent material is less than 3% at about 175 °C and less than 10% at about 250 °C. At 275 °C, the quenching may be up to about 15%. 25 °C is used as reference.

[0185] Fig. 5 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. 5 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. 5 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.

[0186] Fig. 5 also schematically depicts an embodiments of an outdoor light, or stage light, or stadium light. Fig. 5 also schematically depicts a vehicle, like an automobile, but this2024PF80402

[0187] 27

[0188] may also be a truck, a motor cycle, etc. etc., with automotive lighting 4, e.g. headlights. These automotive lighting 4 may also comprise the lighting device 1200.

[0189] 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". 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. 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. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0190] 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.

[0191] 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.2024PF80402

[0192] 28

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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

1. 2024PF8040229CLAIMS:

1. A light generating system (1000) comprising (a) a light generating unit (2000) and (b) a control system (300); wherein:the light generating unit (2000) comprises (i) a first light generating device (110), configured to generate first device light (111), having a first peak wavelength kpl selected from the 440-490 nm wavelength range, wherein the first light generating device (110) comprises a first solid state light source (10), comprising one or more of a laser diode, a superluminescent diode, and a multi -junction light emitting diode; and (ii) a first luminescent material (210), configured to convert at least part of the first device light (111) into first luminescent material light (211); wherein the light generating unit (2000) is configured to generate unit light (2001) comprising first luminescent material light (211); wherein the first luminescent material (210) comprises M3AlxSi6-xNn-x / 3:Ce3+, wherein M comprises one or more of Sc, Y, La, Gd, Tb, and Lu, and wherein x is selected from the range of 0-1;the light generating system (1000) is configured to generate system light (1001) comprising in an operational mode of the light generating system (1000) unit light (2001); andthe control system (300) is configured to control a spectral power distribution of the system light (1001) by controlling, in an operational mode of the light generating system (1000), a spectral power distribution of the unit light (2001); wherein the control system (300) is configured to control the spectral power distribution of the unit light (2001) by controlling a temperature of the first luminescent material (210); and wherein the light generating system (1000) is configured such that a CIE u’ value of the unit light (2001) is controllable by controlling the temperature of the first luminescent material (211) over a range of at least 0.005.

2. The light generating system (1000) according to claim 1, wherein the first light generating device (110) comprises a pulsed first solid state light source (10); wherein the control system (300) is configured to control the temperature of the first luminescent material2024PF8040230(210) by controlling one or more of pulse width, pulse height, and pulse frequency of the first device light (111).

3. The light generating system (1000) according to any one of the preceding claims, comprising a first luminescent material support (710) configured to support the first luminescent material (210); wherein the control system (300) is configured to control the temperature of the first luminescent material (210) by controlling a temperature of the first luminescent material support (710).

4. The light generating system (1000) according to any one of the preceding claims, comprising a rotatable element (1200); wherein the first luminescent material (210) is comprised by the rotatable element; wherein the control system (300) is configured to control the temperature of the first luminescent material (210) by controlling a rotational frequency of the rotatable element (1200).

5. The light generating system (1000) according to any one of the preceding claims, further comprising a temperature control element (1260) configured to heat or cool the first luminescent material (210); wherein the control system (300) is configured to control the temperature control element (1260).

6. The light generating system (1000) according to any one of the preceding claims, wherein the light generating system (1000) is configured such that the temperature of the first luminescent material (211) is controllable over a range of at least 125 °C.

7. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to maintain the temperature of the first luminescent material (211) below 250 °C; wherein x=0; wherein the first peak wavelength kpl selected from the 440-460 nm; wherein the first solid state light source (10) comprises a laser diode.

8. The light generating system (1000) according to any one of the preceding claims, wherein M comprises one or more of Y and La; and wherein the light generating system (1000) is configured such that a CIE u’ value of the unit light (2001) is controllable2024PF8040231by controlling the temperature of the first luminescent material (211) over a range of at least 0.01.

9. The light generating system (1000) according to any one of the preceding claims 1-8, wherein the light generating unit (2000) is configured to generate unit light (2001) having a spectral power distribution in the wavelength range of 380-780 nm, wherein selected from the range of 0.25-25% of the spectral power is in the 380-490 nm wavelength range; and wherein the unit light (2001) is white light.

10. The light generating system (1000) according to any one of the preceding claims 1-8, wherein less than 0.2% of the spectral power of the unit light (2001) is in the 380-490 nm wavelength range.

11. The light generating system (1000) according to any one of the preceding claims, wherein the first luminescent material light (211) has a first centroid wavelength Xcl; wherein the light generating system (1000) further comprises a second light generating device (120); wherein the second light generating device (120) is configured to generate second device light (121) having a second centroid wavelength Xc2; wherein the second light generating device (120) comprises a second solid state light source (20); wherein | Xc2-Xcl|> 20 nm.

12. The light generating system (1000) according to any one of the preceding claims, wherein the light generating system (1000) further comprises a third light generating device (130) configured to generate third device light (131) having a third centroid wavelength Xc3; wherein the third light generating device (130) comprises a third solid state light source (30); wherein |Xc3-Xcl|> 20 nm; and wherein the third centroid wavelength Xc3 is selected from the wavelength range of 430-490 nm.

13. The light generating system (1000) according to claims 11 and 12, wherein: the light generating system (1000) is configured such that a CIE u’ value of the unit light (2001) is selected from the range of 0.19-0.28; and wherein the second centroid wavelength Xc2 is selected from the wavelength range of 560-680 nm.2024PF804023214. The light generating system (1000) according to any one of the preceding claims, wherein the system light (1001) is, in an operational mode of the light generating system (1000), white system light (1001); wherein a correlated color temperature of the white system light (1001) is controllable by controlling the temperature of the first luminescent material (211); wherein the light generating system (1000) is configured such that the correlated color temperature of the white system light (1001) is controllable over a range of at least 500 K.

15. A lighting device (1200) selected from the group of a lamp (1), a luminaire (2), a projector device (3), a lighting fixture, comprising the light generating system (1000) according to any one of the preceding claims.

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