A light generating system

Abstract

A light generating system (1) configured to, in operation, emit system light (2) and comprising: a first solid state light source (3) configured to, in operation, emit first light source light (4) having a first peak emission wavelength, λ1, being in the range of 420 nm to 490 nm; a luminescent element (5) being arranged downstream of the first solid state light source (4) and configured to convert at least a part of the first light source light (4) into first converted light (6) having a second peak emission wavelength, λ2, being in the range of 500 nm to 590 nm, the luminescent element (5) comprising a first major surface (51); and a first specular reflecting element (7) arranged in front of and remote of the luminescent element (5), the first specular reflecting element (7) being arranged and configured to reflect the first light source light (4) and direct it onto the luminescent element (5) such that the first light source light (4) impinges on the luminescent element (5) perpendicular to the first major surface (51) of the luminescent element (5), the first specular reflecting element (7) being transmissive for the first converted light (6); and a collimator (11) arranged downstream of the luminescent element (5) and configured to collimate a part of the first light source light (4) and the first converted light (6); wherein the system light (2) in an operational mode comprises a combination of the part of the first light source light (4) and the first converted light (6), and is white light having a correlated color temperature in a range from 2000K to 9000K and a color rendering index of at least 80.

Description

[0001] 2024PF80400

[0002] A light generating system

[0003] FIELD OF THE INVENTION

[0004] The invention relates to a light generating system configured to, in operation, emit system light. The invention further relates to a lamp or a luminaire comprising such a light generating system.

[0005] As used herein, the term “violet light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 380 nm to 420 nm.

[0006] As used herein, the term “blue light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 420 nm to 490 nm.

[0007] As used herein, the term “green-yellow light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 500 nm to 590 nm.

[0008] As used herein, the term “green light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 500 nm to 550 nm.

[0009] As used herein, the term “yellow light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 550 nm to 590 nm.

[0010] As used herein, the term “yellow-orange light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 550 nm to 600 nm.

[0011] As used herein, the term “red light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 600 nm to 680 nm.

[0012] As used herein, the term “white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 2000 K to 9000 K, preferably in a correlated color temperature range of 2700 K to 6500 K.

[0013] As used herein, the term “cool white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 3500 K to 6500 K.

[0014] As used herein, the term “extreme cool white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 6500 K to 9000 K.

[0015] As used herein, the term “warm white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 2000 K to 3500 K.2024PF80400

[0016] 2

[0017] As used herein, the term “solid state light source” is intended to refer to any solid state light source, including LEDs as well as diode lasers, super-luminescent diodes, and multi -junction diodes, comprising one or more LEDs.

[0018] BACKGROUND OF THE INVENTION

[0019] Laser-phosphor technology is used in high-end lighting applications such as automotive headlights, projection, and stage-lighting. Recent advancements have simplified and miniaturized the technology such that it can also be used in other lighting applications such as spotlights and flashlights. However, current simplified and miniaturized architectures are not meeting the light quality requirements of general lighting set by major lighting companies.

[0020] WO2022 / 073895A1 discloses a light generating system comprising a laser, a luminescent body and first optics. The luminescent body comprises a luminescent material, wherein the luminescent material is configured to convert at least part of the laser light and wherein the luminescent body is transmissive for at least part of the luminescent material light. The first optics are transmissive for at least part of the device light and reflective for at least part of the luminescent material light. The first optics comprise a primary optic surface having a first surface area Al wherein the primary optic surface is configured in a light receiving relationship with the light generating device. The luminescent body is enclosed by a cavity having a cavity opening having a smallest cross-sectional area A2, wherein the cavity is at least partly defined by the optics. The first optics comprise the cavity opening, wherein A2 < AL The cavity being reflective for the luminescent material light and the luminescent material light substantially only exiting the cavity via the cavity opening.

[0021] WO2024 / 022844A1 discloses a light generating system comprising one or more light generating devices, a first luminescent body, a second luminescent body, an optics arrangement, a collimator, a heat transfer system, and a control system. The one or more light generating devices are configured to generate device light having a first wavelength and having a controllable polarization. The collimator has a first end and a second end, wherein the collimator tapers from the second end to the first end. The first luminescent body is configured to convert at least part of light having the first wavelength into first luminescent material light. The second luminescent body and is configured to convert at least part of light having the first wavelength (XI) into second luminescent material light. The first luminescent body is configured closer to the first end than the second luminescent body. The optics arrangement is configured to direct the device light to the first luminescent body or the2024PF80400

[0022] 3

[0023] second luminescent body in dependence of the polarization of the device light. The control system is configured to control the polarization of the device light.

[0024] W02022 / 063608A1 discloses a system for generating system light, and having a laser that excites a first luminescent material via a first dichroic element. The first luminescent element is arranged on a first heat sink and is converting laser light into first converted light. The first dichroic element is used to prevent that the first converted light is redirected to the first laser light source. The first dichroic element is arranged between the first laser light source and the first luminescent element and is reflective for the laser light and transparent for the first converted light. The system further comprises an additional laser, a second luminescent element and further optics.

[0025] CN112709973 A discloses a light path structure for generating composite light by using a laser. Laser light is reflected and directed to the surface of a fluorescent body to generate primary composite light. The fluorescent body is provided with a reflecting layer capable of reflecting the primary composite light.

[0026] It is therefore desired to improve the light quality of the simplified and miniaturized architectures of light generating systems configured to, in operation, emit system light. It is further desired to provide a light generating system with improved optical performance, such as improvement in one or more of color over angle, spatial light distribution, and optimized flood-spot light ratio.

[0027] SUMMARY OF THE INVENTION

[0028] It is an object of the present invention to overcome this problem, and to provide a light generation system with a simplified and miniaturized architecture, which light generating system, in operation, emits system light with an improved light quality.

[0029] It is further desired to provide such a light generating system with an improved optical performance, such as improvement in one or more of color over angle, spatial light distribution, and optimized flood-spot light ratio.

[0030] According to a first aspect of the invention, this and other objects are achieved by means of a light generating system configured to, in operation, emit system light, the light generating system comprising: a first solid state light source configured to, in operation, emit first light source light having a first peak emission wavelength, I, being in the range of 420 nm to 490 nm, the first solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode; a luminescent element being arranged downstream of the first solid state light source and being configured2024PF80400

[0031] 4

[0032] to convert at least a part of the first light source light into first converted light having a second peak emission wavelength, X2, being in the range of 500 nm to 590 nm, the luminescent element comprising a first major surface and a second major surface opposite to the first major surface, and a first specular reflecting element arranged in front of and remote of the luminescent element, the first specular reflecting element being arranged and configured to reflect the first light source light and to direct the first light source light onto the luminescent element such that the first light source light impinges on the luminescent element perpendicular to the first major surface of the luminescent element, wherein the first specular reflecting element is transmissive for the first converted light, wherein a collimator is arranged downstream of the luminescent element and downstream of the first specular reflecting element and is configured to collimate a part of the first light source light reflected by the luminescent element and the first converted light; and wherein the system light, in an operational mode of the light generating system, comprises a combination of the part of the first light source light reflected by the luminescent element and the first converted light, and the system light is white light having a correlated color temperature, CCT, in a range from 2000 K to 9000 K and a color rendering index, CRI, of at least 80.

[0033] The system light may have a CCT in a range from 2000 K to 9000 K, from 2500 K to 6500 K, or from 2700 K to 4500 K, and / or a CRI of at least 70, at least 80, at least 85 or at least 90.

[0034] Thereby, a light generation system with a simplified and miniaturized architecture, which light generating system, in operation, emits system light with an improved light quality, is provided for.

[0035] Such a light generating system furthermore exhibits an improved optical performance, such as an improvement in one or more of color over angle, spatial light distribution, and optimized flood-spot light ratio.

[0036] The first peak emission wavelength may be in a wavelength range from 430 nm to 470 nm.

[0037] The second peak emission wavelength may be in a wavelength range from 520 nm to 570 nm.

[0038] The third peak emission wavelength may be in a wavelength range from 430 nm to 470 nm.

[0039] The fourth peak emission wavelength may be in a wavelength range from 520 nm to 570 nm.

[0040] It may apply that I 3- XI I > 20 nm or that I 3- XI I > 30 nm.2024PF80400

[0041] 5

[0042] The effect is a change in color point obtained by having different first and second (blue) light source lights, different amounts of first and second (blue) light source light reflection due to differences in wavelength and reflection properties of the phosphor, and different amount of conversion due to differences in wavelength and excitation properties of the phosphor.

[0043] The first specular reflecting element may be centrally arranged with respect the luminescent element.

[0044] The second specular reflecting element may be arranged in front of the luminescent element and non-centrally arranged with respect the luminescent element.

[0045] The collimator may be arranged downstream of the first and second specular reflecting elements.

[0046] The first specular reflecting element may be arranged and configured to reflect the first light source light and to direct the first light source light onto the luminescent element such that the first light source light impinges on the luminescent element in an angle of 90 degrees + / -5 degrees, or in an angle of 90 degrees + / -2 degrees, to the first major surface of the luminescent element.

[0047] Such a light generating system furthermore exhibits a particularly good optical performance. Especially, such a light generating system enables obtaining an advanced light distribution, or even beam control when using a controller.

[0048] The first converted light may be yellow light, green-yellow light, or orangeyellow light. The second converted light may be yellow light, green-yellow light, or orangeyellow light.

[0049] The first specular reflecting element may be transparent for the first converted light.

[0050] Thereby reflection of the first converted light at the first specular reflecting element may be minimized or avoided altogether.

[0051] The first specular reflecting element may comprise a reflective polarizer configured to reflect first light source light and to transmit at least part of the first converted light.

[0052] Alternatively, the first specular reflecting element may comprise a blue dichroic mirror configured to reflect first light source light and to transmit at least part of the first converted light.

[0053] Thereby, a particularly simple and efficient first specular reflecting element is provided for.2024PF80400

[0054] 6

[0055] The first specular reflecting element may comprise a narrow reflection band of less than 30 nm, or less than or equal to 25 nm, or less than or equal to 20 nm, or less than or equal to 15 nm, in a wavelength range of 420 nm to 490 nm.

[0056] Thereby reflection of light of other wavelengths, such as the first converted light, or the second light source light or second converted light to be described further below, at the first specular reflecting element may be minimized or avoided altogether.

[0057] The first specular reflecting element may be configured to reflect at least 90 %, at least 95 %, at least 97 %, at least 99 %, such as 100 %, of the first solid state light source light e.g. incident in an angle being between 40 and 50 degrees, between 43 and 47 degrees, or between 44 and 46 degrees.

[0058] Thereby, loss of first light source light during reflection of the first light source light received by the first specular reflecting element from the first solid state light source may be minimized or avoided altogether.

[0059] The first specular reflecting element may be configured to transmit at least 30% or at least 50 % of the first solid state light source light reflected by the luminescent element and incident on the first specular reflecting element in an angle being below 30 degrees or above 60 degrees, such as in a range of 5 to 30 degrees or in a range of 60 to 85 degrees.

[0060] Thereby, loss of first light source light reflected by the luminescent element at the first specular reflecting element may be minimized or avoided altogether.

[0061] The first specular reflecting element may be at least 40% or at least 60% or at least 80% such as at least 90% transmissive (or transparent) for the first converted light impinging on the first specular reflecting element.

[0062] The first specular reflecting element may be transmissive or transparent for at least part of the first solid state light source light reflected by the luminescent element e.g. at least 20% or at least 40% or at least 60% of the light source light reflected by the luminescent element and impinging on the first specular reflecting element is transmitted by the first specular reflecting element.

[0063] Thereby, loss of first light source light reflected by the luminescent element by absorption in the first specular reflecting element may be minimized or avoided altogether.

[0064] The light generating system may further comprise a second reflecting element arranged between the first solid state light source and the first specular reflecting element, the second reflecting element being configured to receive and reflect the first light source light and to direct the first light source light onto the first specular reflecting element.2024PF80400

[0065] 7

[0066] The light generating system may further comprise a heat sink element, wherein the luminescent element is in (i) thermal or (ii) thermal and physical contact with the heatsink element via the second major surface facing or being in direct contact with the heat sink element.

[0067] Thereby, efficient and sufficient cooling of the luminescent element is provided for, which in turn further improves the quality of the device light emitted by the light generating system.

[0068] An element or a layer being reflective to first converted light and first light source light may be arranged between the luminescent element and the heat sink element.

[0069] Thereby, further improved cooling of the luminescent element is provided for. The light generating system may further comprise a optical element arranged downstream of the luminescent element and being (i) an optical element being transparent or translucent for the first converted light and the first solid state light source light reflected by the luminescent element, or (ii) a diffusing element configured to diffuse the system light.

[0070] Such an optical element serves at least one of two purposes, namely to close off the housing from the surroundings such as to protect the optical components from external influences, and to enhance the light quality of the device light even further.

[0071] The light generating system may further comprise a second solid state light source configured to, in operation, emit second light source light comprising a third peak emission wavelength, 3, being in the range of 420 nm to 490 nm, the second solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode, and a third specular reflecting element arranged in front of and remote of the luminescent element, the third specular reflecting element being arranged to reflect the second light source light and to direct the second light source light onto the luminescent element, wherein the luminescent element further is arranged downstream of the second solid state light source and further is configured to convert at least a part of the second light source light into second converted light, the second converted light comprising a fourth peak emission wavelength, X4, being in the range of 500 nm to 590 nm, wherein the first specular reflecting element is transparent for the first converted light and for the second converted light, and wherein the system light comprises a combination of the first light source light, the first converted light, the second light source light, and the second converted light.2024PF80400

[0072] 8

[0073] Thereby, a light generation system with a simplified and miniaturized architecture, which light generating system, in operation, emits system light with a further improved light quality, and especially an increased intensity, is provided for.

[0074] The third specular reflecting element may be configured to direct the second light source light onto the luminescent element such that the second light source light impinges on the luminescent element in an angle, a, of between 20 and 70 degrees with the first major surface of the luminescent element.

[0075] The third specular reflecting element may be arranged and configured to reflect the first light source light and to direct the first light source light onto the luminescent element such that the first light source light impinges perpendicular to the first major surface of the luminescent element.

[0076] The light generating system may further comprise a fourth reflecting element arranged between the second solid state light source and the second specular reflecting element, the fourth reflecting element being configured to receive and reflect the second light source light and to direct the second light source light onto the third specular reflecting element.

[0077] The first major surface has a surface area, Al, the first specular reflecting element has a largest surface area, A2, and it may apply that A2 < 0.8*Al, that A2 < O.6*A1, that A2 < 0.5*Al, or that A2 < O.2*A1.

[0078] The largest surface area, A2, is the area where part of the first converted light is impinging on the first specular reflecting element.

[0079] A first fraction of the first converted light, Fl, is impinging on the first specular reflecting element and a second fraction of the first converted light, F2, is bypassing the first specular reflecting element, and it may apply that F2 > 1.2*F1, that F2 > 1.5*F1, that F2 > 1.8*Fl, thatF2 > 2*Fl, or thatF2 > 3*F1.

[0080] The obtained effect is improved efficiency and / or homogeneity of the system light. The reason is that the major part of the first converted light is not imping on the first specular reflecting element.

[0081] A third fraction of the first light source light reflected by the luminescent element, F3, is impinging on the first specular reflecting element and a fourth fraction of the first light source light reflected by the luminescent element, F4, is bypassing the first specular reflecting element, and it may apply that F4 > 1.2*F3, that F4 > 1.5*F3, that F4 > 1.8*F3, that F4 > 2*F3, or that F4 > 3*F2.2024PF80400

[0082] 9

[0083] The first specular reflecting element may have a (largest) dimension of at most 7 mm, of at most 5 mm, of at most 4 mm, or of at most 3 mm.

[0084] The light generating system may further comprise a controller configured to individually control the first solid state light source and, where provided, the second solid state light source.

[0085] The controller may be configured to individually control the first light source light and the second light source light.

[0086] The controller may further be configured to individually control the intensity of the first light source light and the intensity of the second light source light.

[0087] Thereby, it becomes possible to adapt the obtained device light to various different applications and to the light requirements thereof. For instance, it becomes possible to control the light generating system to emit either spotlight, for instance for visualizing objects, or flood light, for instance for orientation. It also becomes possible to control the flood-spot light ratio. Furthermore, it becomes possible to control the correlated color temperature, CCT, and the color rendering index, CRI of the device light.

[0088] The intensity of the second light source light impinging on the first major surface of the luminescent element may be configured to be adaptable. Alternatively, or additionally, the intensity of the first light source light impinging on the first major surface of the luminescent element may be configured to be adaptable.

[0089] Thereby, it becomes possible to adapt the flood-spot light ratio.

[0090] The light generating system may further comprise a first further optical element arranged downstream of the first solid state light source and configured to collimate the first light source light.

[0091] Thereby, loss of first light source light before the first light source light reaches the first specular reflecting element may be minimized or avoided altogether.

[0092] The light generating system may further comprise a second further optical element arranged downstream of the second solid state light source and configured to collimate the second light source light.

[0093] Thereby, loss of second light source light before the second light source light reaches the second specular reflecting element may be minimized or avoided altogether.

[0094] The light generating system may further comprise a housing configured to house the luminescent element and the first specular reflecting element, as well as, where provided, the second reflecting element, the collimator, and the optical element.2024PF80400

[0095] 10

[0096] Thereby, the elements arranged in the housing are protected from external influences. This in turn makes the light generation system more robust.

[0097] The housing may comprise an inner surface facing the luminescent element and the first specular reflecting element, the inner surface comprising a light reflective layer or coating.

[0098] Thereby light losses which may otherwise occur by absorption in the housing wall are minimized.

[0099] The light generating system may further comprise a focusing optical element arranged upstream of the luminescent element and configured to focus the second light source light onto the luminescent element.

[0100] Thereby, it may be ensured that all, or as good as all, second light source light, which it is intended to convert by the luminescent element, reaches the luminescent element.

[0101] The invention further relates to a lamp or a luminaire, a vehicle light, projection device, a search light, or a stage lighting device comprising a light generating system according to the invention.

[0102] The lamp or the luminaire - or the vehicle light, or the projection device, or the search light, or the stage lighting device - may, thanks to the light generating system, provide system light with an improved brightness and / or an improved color quality.

[0103] The lamp or luminaire may be any type of lamp and luminaire, but particularly an automotive headlight, a projection luminaire, a stage lighting luminaire or fixture and a flashlight.

[0104] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0105] BRIEF DESCRIPTION OF THE DRAWINGS

[0106] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0107] Fig. 1 schematically shows a light generating system according to the invention and comprising a first solid state light source and a luminescent element.

[0108] Fig. 2 schematically shows another light generating system according to the invention and comprising a first and a second solid state light source and a luminescent element.

[0109] Fig. 3 schematically shows a close up of the section III of the light generating system according to Fig. 2.2024PF80400

[0110] 11

[0111] Fig. 4 schematically shows another light generating system according to the invention and comprising a first and a second solid state light source and a luminescent element.

[0112] Figs. 5 and 6 are two different graphs showing the reflection in percent as a function of the wavelength of the incident light for the first specular reflecting element.

[0113] Fig. 7 shows a graph of the intensity in arbitrary units as a function of the wavelength of emission (Em; solid line) and excitation (Ex; dashed line), respectively, for a YAG phosphor.

[0114] Fig. 8 shows a schematical side view of a lamp comprising a light generating system according to the invention.

[0115] Fig. 9 shows a schematical side view of a luminaire comprising a lamp and a light generating system filament according to the invention.

[0116] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

[0117] DETAILED DESCRIPTION

[0118] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0119] Fig. 1 schematically shows a light generating system 1 according to the invention. Irrespective of the embodiment, the light generating system 1 comprises a first solid state light source 3 and a luminescent element 5, and the light generating system 1 is configured to, in operation, emit system light 2.

[0120] The first solid state light source 3 is configured to, in operation, emit first light source light 4 comprising a first peak emission wavelength, LI , being in the range of 420 nm to 490 nm. The first light source light 4 is blue light. The first solid state light source 3 comprises one or more of a laser diode, a super-luminescent diode, and a stacked multijunction light-emitting diode.2024PF80400

[0121] 12

[0122] The luminescent element 5 comprises a first major surface 51 and a second major surface 52 opposite to the first major surface 51. The luminescent element 5 is arranged downstream of the first solid state light source 3. The luminescent element 5 is configured to convert at least a part of the first light source light 4 into first converted light 6. The first converted light 6 comprises a second peak emission wavelength, X2, being in the range of 500 nm to 590 nm. The first converted light 6 may be yellow light, green-yellow light, or orange-yellow light.

[0123] A first specular reflecting element 7 is arranged in front of and remote of the luminescent element 5. The first specular reflecting element 7 is arranged and configured to reflect the first light source light 4 and to direct the first light source light 4 onto the luminescent element 5 such that the first light source light 4 impinges on the luminescent element 5 perpendicular to the first major surface 51 of the luminescent element 5. The first specular reflecting element 7 may for instance be arranged and configured to direct the first light source light 4 onto the luminescent element 5 such that the first light source light 4 impinges on the luminescent element in an angle of 90 degrees + / -5 degrees, or in an angle of 90 degrees + / -2 degrees, to the first major surface 51 of the luminescent element 5. The first specular reflecting element 7 is configured to reflect the first solid state light source light 4 under an angle being between 40 and 50 degrees.

[0124] The first specular reflecting element 7 may be transparent for the first converted light 6. For instance, the first specular reflecting element 7 may have a reflectance as illustrated in Fig. 5 showing a graph illustrating the reflection in percent as a function of the wavelength of the incident light.

[0125] The first specular reflecting element 7 may comprise or be a polarizing beam splitter. The polarizing beam splitter is transparent for first solid state light source light 4 reflected by the luminescent element 5.

[0126] Alternatively, the first specular reflecting element 7 may comprise or be a narrow-band blue dichroic element. The reflection band of the narrow-band blue dichroic element is less than 20 nm. The narrow-band blue dichroic element may be configured to reflect first solid state light source light 4 incident in an angle being between 40 and 50 degrees, between 43 and 47 degrees, or between 44 and 46 degrees, only. Thereby, the first specular reflecting element 7 is transparent for first solid state light source light 4 reflected by the luminescent element 5. For instance, the first specular reflecting element 7 may be a narrow-band blue dichroic element having a reflectance as illustrated in Fig. 6 showing a2024PF80400

[0127] 13

[0128] graph illustrating the reflection in percent as a function of the wavelength of the incident light.

[0129] A collimator 11 is arranged downstream of the luminescent element 5. The collimator 11 is configured to collimate a part of the first light source light 4 and the first converted light 6.

[0130] In an operational mode, the system light 2 generated by the light generating system 1 comprises a combination of the part of the first light source light 4 and the first converted light 6. Therefore, the collimator 11 is in other words configured to collimate the system light 2.

[0131] The first light source light 4 forms a first spot on the luminescent element 5. The first spot comprises a first spot size, a first spot shape, and a first spot position on the first major surface 51 of the luminescent element 5. The first spot may be arranged centered with respect to the collimator 11.

[0132] The light generating system 1 further comprises a controller 28. The controller 28 is configured to control the first light source light 4. The controller 28 is further configured to control the intensity of the first light source light 4. Alternatively, or additionally, the controller 28 may be configured to control a first spot size of the first light source light 4 on the luminescent element 5. Alternatively, or additionally, the controller 28 may be configured to control a first spot shape of the first light source light 4 on the luminescent element 5. Alternatively, or additionally, the controller 28 may be configured to control a first spot position of the first light source light 4 on the luminescent element 5.

[0133] The light generating system 1 further comprises an optional third reflecting element 8. The third reflecting element 8 is arranged between the first solid state light source 3 and the first specular reflecting element 7. The third reflecting element 8 is configured to receive and reflect the first light source light 4 and to direct the first light source light 4 onto the first specular reflecting element 7. The third reflecting element 8 is or may be a specular reflecting element.

[0134] The light generating system 1 further comprises an optional optical element 12. The optical element 12 is arranged downstream of the luminescent element 5. The optical element 12 may be a transparent or translucent optical element. The optical element 12 may be transparent or translucent for the first converted light 6 and the first solid state light source 4 light reflected by the luminescent element 5. Alternatively, the optical element 12 may be a diffusing element configured to diffuse the system light 2. The optical element 12 may for instance be a light exit window, such as a transparent plate, or a further lens.2024PF80400

[0135] 14

[0136] The light generating system 1 further comprises an optional heat sink element 9. The luminescent element 5 is arranged with the second major surface 52 facing or in direct contact with the heat sink element 9. The heat sink element 9 cools the luminescent element 5. The heat sink element 9 may further be configured to cool the first solid state light source 3.

[0137] The light generating system 1 further comprises an optional element or layer 10 being reflective to light and transmissive to heat. The element or layer 10 is arranged between the luminescent element 5 and the heat sink element 9.

[0138] The light generating system 1 further comprises an optional first further optical element 22 (shown in Fig. 2). The first further optical element 22 is arranged downstream of the first solid state light source 3. The first further optical element 22 is configured to collimate the first light source light 4.

[0139] The light generating system 1 further comprises an optional housing 13. The housing 13 is configured to house the luminescent element 5 and the first specular reflecting element 7, as well as, where provided, the reflecting element 8, the collimator 11, and the optical element 12. The housing 13 comprises an inner surface 14 facing the luminescent element 5 and the first specular reflecting element 7. The inner surface 14 may comprise a light reflective layer or coating.

[0140] Fig. 2 schematically shows another light generating system 100 according to the invention. Fig. 3 schematically shows a close up of the section III of the light generating system 100 according to Fig. 2. The light generating system 100 differs from the light generating system 1 according to Fig. 1 and described above in that it further comprises a second solid state light source 15.

[0141] The second solid state light source 15 is configured to, in operation, emit second light source light 16. The second light source light 16 comprises a third peak emission wavelength, X3, being in the range of 420 nm to 490 nm. The second light source light 16 is blue light. The first peak emission wavelength, XI, and the third peak emission wavelength, X3, may be the same or may be different from one another. For instance, the first peak emission wavelength, I, and the third peak emission wavelength, X3, may be chosen such that I X3- XI I > 20 nm. The second solid state light source 15 comprises one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode.

[0142] The luminescent element 5 is further arranged downstream of the second solid state light source 15. The luminescent element 5 is further configured to convert at least a part of the second light source light 16 into second converted light 18. The second converted2024PF80400

[0143] 15

[0144] light 18 comprises a fourth peak emission wavelength, 4, being in the range of 500 nm to 590 nm. The second converted light 18 may be yellow light, green-yellow light, or orangeyellow light.

[0145] The first specular reflecting element 7 may be transparent for both the first converted light 6 and for the second converted light 18.

[0146] A second specular reflecting element 17 is arranged remote of the luminescent element 5. The second specular reflecting element 17 is configured to reflect the second light source light 16 and to direct the second light source light 16 onto the luminescent element 5 such that the second light source light 16 impinges on the luminescent element 5 in an angle, a, of between 20 and 70 degrees with the first major surface 51 of the luminescent element 5.

[0147] The collimator 11 is further configured to collimate a part of the second light source light 16 and the second converted light 18.

[0148] In an operational mode, the system light 2 generated by the light generating system 100 comprises a combination of the part of the first light source light 4, the first converted light 6, the part of the second light source light 16, and the second converted light 18.

[0149] The intensity of the first light source light 16 impinging on the first major surface 51 of the luminescent element 5 may be different from the intensity of the second light source light 16 impinging on the first major surface 51 of the luminescent element 5. The difference in intensity may be at least 20 % or at least 40 %. The intensity of the second light source light 16 impinging on the first major surface 51 of the luminescent element 5 may be configured to be adaptable. Alternatively, or additionally, the intensity of the first light source light 4 impinging on the first major surface 51 of the luminescent element 5 may be configured to be adaptable.

[0150] The first light source light 4 forms a first spot on the luminescent element 5. The first spot comprises a first spot size, a first spot shape, and a first spot position on the first major surface 51 of the luminescent element 5. Likewise, the second light source light 16 forms a second spot on the luminescent element 5. The second spot comprises a second spot size, a second spot shape, and a second spot position on the first major surface 51 of the luminescent element 5.

[0151] The first spot size may be different from the second spot size. For instance, the spot size may be different from the second spot size by at least 20 %, or by at least 40 %. The first spot size may be smaller than the second spot size. For instance, the first spot size may be smaller than the second spot size by at least 20 %, or by at least 40 %. Alternatively, the2024PF80400

[0152] 16

[0153] first spot size may be larger than the second spot size. For instance, the first spot size may be larger than the second spot size by at least 20 %, or by at least 40 %.

[0154] The first spot shape may be different from the second spot shape. The first spot shape may be different from the second spot shape in terms of size or area or orientation or a combination thereof. Alternatively, the first spot shape may be identical to the second spot shape. The first spot shape and the second spot shape may for instance be round vs. nonround, such as elliptical, or vice versa.

[0155] The first spot position may be different from the second spot position. For instance, the first spot and the second spot may be arranged to overlap one another at least partly. For instance, the overlap between the first spot and the second spot may be at least 60 %, or at least 70 %, or at least 80 %, or at least 90 %. Alternatively, the first spot and the second spot may be arranged centered with respect to each other. The first spot position and the second spot position may be centered vs. non-centered, or vice versa.

[0156] Furthermore, the first spot and the second spot may be arranged centered with respect to the collimator 11.

[0157] The light generating system 100 further comprises a controller 28. The controller 28 is configured to individually control the first light source light 4 and the second light source light 16. The controller 28 is further configured to individually control the intensity of the first light source light 4 and the second light source light 16. Alternatively, or additionally, the controller 28 is further configured to control the first spot size of the first light source light 4 on the luminescent element 5 and the second spot size of the second light source light 16 on the luminescent element 5. Alternatively, or additionally, the controller 28 is further configured to control the first spot shape of the first light source light 4 on the luminescent element 5 and the second spot shape of the second light source light 16 on the luminescent element 5. Alternatively, or additionally, the controller 28 is further configured to control the first spot position of the first light source light 4 on the luminescent element 5 and the second spot position of the second light source light 16 on the luminescent element 5.

[0158] The light generating system 100 may further optionally comprise a second further optical element 23. The second further optical element 23 is arranged downstream of the second solid state light source 15. The second further optical element 23 is configured to collimate the second light source light 16.

[0159] The light generating system 100 further comprises an optional heat sink element 9. The luminescent element 5 is arranged with the second major surface 52 facing or in direct contact with the heat sink element 9. The heat sink element 9 cools the luminescent2024PF80400

[0160] 17

[0161] element 5. The heat sink element 9 may further be configured to cool the first solid state light source 3. The heat sink element 9 may further be configured to cool the second solid state light source 15.

[0162] Referring also to Fig. 3, the light generating system 100 may further comprise an optional first focusing optical element 29. The first focusing optical element 29 is arranged upstream of the luminescent element 5 and downstream of the second specular reflecting element 17. The first focusing optical element 29 is configured to focus the second light source light 16 onto the luminescent element 5.

[0163] Fig. 4 schematically shows another light generating system 101 according to the invention. The light generating system 101 differs from the light generating system 100 according to Fig. 2 and described above in that the second light source light 16 impinges perpendicular to the luminescent element 5. In other words, the angle a with the first major surface 51 of the luminescent element 5 is in this case chosen to be 90 degrees, or 90 degrees + / -2 degrees, or 90 degrees + / -5 degrees.

[0164] The second reflecting element 17 of the light generating system 101 is a specular reflecting element. The second reflecting element 17 is arranged in front of and remote from the luminescent element 5. As shown in Fig. 4, the second reflecting element 17 is arranged behind the first reflecting element 7. Alternatively, the second reflecting element 17 may be arranged either in front of the first reflecting element 7. The second reflecting element 17 is configured to reflect the second light source light 16 and to direct the second light source light 16 onto the luminescent element 5 such that the second light source light 16 impinges perpendicular to the luminescent element 5.

[0165] The light generating system 101 further comprises an optional third reflecting element 19. The third reflecting element 19 is arranged between the second solid state light source 15 and the further specular reflecting element 17. The third reflecting element 19 is configured to receive and reflect the second light source light 16 and to direct the second light source light 16 onto the further specular reflecting element 17.

[0166] Referring now to Fig. 7, different suitable phosphors for a light generating system 1 according to the invention will be described.

[0167] Garnet class

[0168] Generally, garnet class phosphors are suitable for use as a luminescent material for the first luminescent element 5. Garnet class phosphors are luminescent materials of the type AsELO Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb2024PF80400

[0169] 18

[0170] and Lu, especially (at least) one or more of Y, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc. Especially, A may comprise one or more of Y, Gd and Lu, such as especially one or more of Y and Lu. Especially, B may comprise one or more of Al and Ga, more especially at least Al, such as essentially entirely Al. Hence, especially suitable luminescent materials are cerium comprising garnet materials.

[0171] Embodiments of garnets especially include A3B5O12 garnets, wherein A comprises at least yttrium or lutetium and wherein B comprises at least aluminum. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B may comprise aluminum (Al); however, in addition to aluminum, B may also partly comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), especially up to about 20% of B, more especially up to about 10 % of B (i.e. the B ions essentially consist of 90 or more mole % of Al and 10 or less mole % of one or more of Ga, Sc and In); B may especially comprise up to about 10% gallium. In another variant, B and O may at least partly be replaced by Si and N. The element A may especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and / or Tb are especially only present up to an amount of about 20% of A. In a specific embodiment, the garnet luminescent material comprises (Yi-xLux)3B50i2:Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1. The term “:Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the “A” ions) in the luminescent material is replaced by Ce. For instance, in the case of (Yi-xLux)3A150i2:Ce, part of Y and / or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will replace A in general for not more than 10%; in general, the Ce concentration will be in the range of 0.1 to 4%, especially 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the full correct formula could be (Yo.iLuo.89Ceo.oi)3A150i2. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art.

[0172] Fig. 7 shows a graph of the intensity in arbitrary units as a function of the wavelength of emission (Em; solid line) and excitation (Ex; dashed line), respectively, for another suitable garnet class phosphor, namely a Yttrium Aluminum Garnet (YAG) phosphor. YAG phosphors are efficient and suitable for creating a high correlated color temperature (CCT). YAG phosphors exhibit absorption peaks at 450 nm, and dominant emission wavelengths range from 540 nm - 560 nm. YAG phosphors can be effectively excited by a 450 nm blue LED chip with an emission peak wavelength in the 540 nm - 560 nm range. YAG phosphors are mainly used for increasing luminous efficiency. By adding a small amount of a YAG yellow phosphor to an Ra80 LED, the luminous flux will increase2024PF80400

[0173] 19

[0174] dramatically. YAG phosphors are particularly suitable for use as a luminescent material for the first luminescent element 5.

[0175] Another suitable garnet class phosphor is a Lutetium Aluminum Garnet (LuAG) phosphor. LuAG phosphors offer performance comparable to YAG phosphors. LuAG phosphors may have dominant emission wavelengths ranging from 520nm to 540 nm. LuAG phosphors are generally used in conjunction with red phosphors for high CRI full spectrum coverage. LuAG phosphors can be effectively excited by a 450nm blue LED with an emission peak wavelength in the 510-540 nm range. Combined with nitride red phosphor, a high CRI spectrum with Ra above 95 can be achieved. LuAG phosphors are particularly suitable for use as a luminescent material for the first luminescent element 5.

[0176] Fig. 8 shows an exemplary lamp 300 comprising a light generating system 1, 100, 101 according to any embodiment of the invention. In the embodiment shown, the light generating system 1, 100, 101 comprises a substantially straight light generating system, such as a light generating system 1, 100, 101 in the form of a LED filament. The light generating system of such a lamp may in other embodiments be a light generating system with another shape, such as, but not limited to, spiral-shaped, helix-shaped, meandering, twisted, flat and combinations thereof.

[0177] The lamp 300 further comprises a driver or controller 305 configured for controlling the solid state light sources 4, 15 of the light generating system 1, 100, 101. The controller 305 is configured to power the solid state light sources 4, 15 via electrical circuitry (not visible on the figures) of the light generating system 1, 100, 101. The light generating system 1, 100, 101 may also comprise a controller 28, which may or may not be separate from the controller 305. In other words, the controller 305 and the controller 28 of the light generating system 1, 100, 101 may be integrated into one and the same driver or controller, or they may be mutually separate units.

[0178] The lamp 300 further comprises an envelope 301 at least partially enveloping the at least one light generating system 1, 100, 101. The lamp 300 further comprises a cap 303. As shown in Fig. 8, the controller 305 is arranged within the envelope 301. When comprising a cap 303, the controller 305 may also be arranged inside the cap 303 such that it is hidden from view. The lamp 300 further comprises threading 302 for connection to a socket, and a terminal 304 for connection to a source of electrical energy.

[0179] The envelope 301 of the lamp 300 may further and optionally be provided with a coating (not shown), such as a reflective coating, covering at least a part of the envelope 301.2024PF80400

[0180] 20

[0181] Turning finally to Fig. 9, an exemplary luminaire in the form of a pendant 400 is shown. The pendant 400 comprises a light generating system 1, 100, 101 according to any embodiment of the invention. The light generating system 1, 100, 101 is as shown in Fig. 9 provided within a lamp 300 in the form of a light bulb. The light generating system 1, 100, 101 as shown in Fig. 9 comprises a substantially straight light generating system, such as a light generating system 1, 100, 101 in the form of a LED filament.

[0182] As is also mentioned above, the light bulb further comprises a transparent envelope (cf. transparent envelope 301 of lamp 300) at least partially enveloping the at least one light generating system 1, 100, 101. The transparent envelope may be shaped in any feasible shape, for example such as to resemble the shape of any one of a standard light bulb, a globe light bulb, a candlelight bulb, a customized light bulb and even a spiral light bulb. The transparent envelope may comprise a luminescent material. The transparent envelope may be a glass envelope.

[0183] The pendant 400 further comprises a socket 401 for connecting the lamp 300, and thereby the light generating system 1, 100, 101, to the pendant 400. The socket 401 is adapted to cooperate with the base 303 of the lamp 300. The socket 401 may comprise a threading adapted to cooperate with the threading 302 of the lamp 300. The socket 401 may comprise a terminal adapted to cooperate with the terminal 304 of the lamp 300. The pendant 400 further comprises a reflector or screen 403.

[0184] The pendant 400 may further comprise a driver 402 configured for controlling the light generating system 1, 100, 101. The driver 402 may or may not be the same unit as the controller 305 described above. In other words, the driver 402 and the controller 305 may be integrated into one and the same driver or controller, or they may be mutually separate units. Alternatively, or additionally, the light generating system 1, 100, 101 may also comprise a controller 28, which may or may not be separate from one or both of the driver 402 and the controller 305.

[0185] As shown in Fig. 9, the driver 402 is arranged on a reflector or screen 403 of the pendant 400. The driver may also be arranged within or incorporated into the reflector or screen 403. The pendant 400 further comprises an electrical wiring 404 for connection to a source of electricity, such as a mains.

[0186] It is noted that the pendant 400 shown in Fig. 9 is only one example of a luminaire according to the invention. Any suitable type of luminaire may be envisaged, such as but not limited to, luminaires for display applications, such as LED displays, LCD displays2024PF80400

[0187] 21

[0188] and OLED displays, a standing luminaire, a wall hung luminaire, a chandelier, a reading luminaire, an outdoor luminaire, and a table luminaire.

[0189] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0190] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

2024PF8040022CLAIMS:

1. A light generating system (1) configured to, in operation, emit system light (2), the light generating system comprising:a first solid state light source (3) configured to, in operation, emit first light source light (4) having a first peak emission wavelength, I, being in the range of 420 nm to 490 nm, the first solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode;a luminescent element (5) being arranged downstream of the first solid state light source and being configured to convert at least a part of the first light source light (4) into first converted light (6) having a second peak emission wavelength, X2, being in the range of 500 nm to 590 nm, the luminescent element (5) comprising a first major surface (51) and a second major surface (52) opposite to the first major surface, anda first specular reflecting element (7) arranged in front of and remote of the luminescent element (5), the first specular reflecting element (7) being arranged and configured to reflect the first light source light (4) and to direct the first light source light (4) onto the luminescent element (5) such that the first light source light (4) impinges on the luminescent element (5) perpendicular to the first major surface (51) of the luminescent element (5); whereinthe first specular reflecting element (7) is transmissive for the first converted light (6); whereinthe first major surface has a surface area, Al, and wherein the first specular reflecting element has a largest surface area, A2, wherein A2 < 0.6* Al; whereinthe first specular reflecting element (7) comprises a narrow reflection band of less than 30 nm in a wavelength range of 420 nm to 490 nm; whereina collimator (11) being arranged downstream of the luminescent element and being arranged downstream of the first specular reflecting element (7), and configured to collimate a part of the first light source light (4) reflected by the luminescent element (5) and the first converted light (6); and whereinthe system light (2) comprises, in an operational mode, a combination of a part of the first light source light (4) reflected by the luminescent element (5) and the first2024PF8040023converted light (6), and the system light (2) is white light having a correlated color temperature in a range from 2000 K to 9000 K and a color rendering index of at least 80.

2. A light generating system according to claim 1, wherein the first specular reflecting element (7) comprises:(i) a reflective polarizer configured to reflect first light source light and to transmit at least part of the first converted light, or(ii) a blue dichroic mirror configured to reflect first light source light and to transmit at least part of the first converted light.

3. A light generating system according to claim 1 or 2, wherein the first specular reflecting element (7) comprises a narrow reflection band of less than or equal to 20 nm in a wavelength range of 420 nm to 490 nm.

4. A light generating system according to any one of the preceding claims, wherein the first specular reflecting element (7) is configured to reflect at least 90 % of the first solid state light source light (4) incident in an angle being between 40 and 50 degrees, between 43 and 47 degrees, or between 44 and 46 degrees.

5. A light generating system according to claim 4, wherein the first specular reflecting element (7) is configured to transmit at least 40 % of the first solid state light source light (4) reflected by the luminescent element and incident on the first specular reflecting element in an angle being between below 30 degrees or above 60 degrees.

6. A light generating system according to any one of the preceding claims, wherein first the specular reflecting element (7) is transmissive for at least part of the first solid state light source light (4) reflected by the luminescent element (5).

7. A light generating system according to any one of the above claims, and further comprising a second reflecting element (8) arranged between the first solid state light source (3) and the first specular reflecting element (7), the second reflecting element (8) being configured to receive and reflect the first light source light (4) and to direct the first light source light (4) onto the first specular reflecting element (7).2024PF80400248. A light generating system according to any one of the above claims, and further comprising a heat sink element (9), wherein the luminescent element (5) is in (i) thermal or (ii) thermal and physical contact with the heatsink element via the second major surface (52) facing or being in direct contact with the heat sink element (9).

9. A light generating system according to claim 8, wherein an element or layer (10) being (i) reflective to first converted and first light source light is arranged between the luminescent element (5) and the heat sink element (9).

10. A light generating system according to any one of the above claims, and further comprising an optical element (12) arranged downstream of the collimator (11), wherein the optical element (12) is a transparent or translucent optical element for the first converted light (6) and the first solid state light source light (4) reflected by the luminescent element (5).

11. A light generating system according to any one of the above claims, and further comprising:a second solid state light source (15) configured to, in operation, emit second light source light (16) comprising a third peak emission wavelength, 3, being in the range of 420 nm to 490 nm, the second solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode, and a third specular reflecting element (17) arranged in front of and remote of the luminescent element (5), the third specular reflecting element (17) being arranged to reflect the second light source light (16) and to direct the second light source light (16) onto the luminescent element (5), whereinthe luminescent element (5) further is arranged downstream of the second solid state light source (15) and further is configured to convert at least a part of the second light source light (16) into second converted light (18), the second converted light comprising a fourth peak emission wavelength, 4, being in the range of 500 nm to 590 nm, wherein the first specular reflecting element (7) is transparent for the first converted light (6) and for the second converted light (18), and whereinthe system light (2) comprises a combination of the first light source light (4), the first converted light (6), the second light source light (16), and the second converted light (18).2024PF804002512. A light generating system according to claim 11, wherein the third specular reflecting element (17) is configured to direct the second light source light (16) onto the luminescent element (5) such that the second light source light (16) impinges on the luminescent element (5) in an angle, a, of between 20 and 70 degrees with the first major surface (51) of the luminescent element (5).

13. A light generating system according to any one of the preceding claims, wherein A2 < 0.5* Al.

14. A light generating system according to any one of the preceding claims, wherein a first fraction of the first converted light, Fl, is impinging on the first specular reflecting element and a second fraction of the first converted light, F2, is bypassing the first specular reflecting element, and wherein F2 > 1.2*F1.

15. A lamp or a luminaire, a vehicle light, projection device, a search light, or a stage lighting device comprising a light generating system (1) according to any one of the above claims.

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