Laser-based high-brightness light sources using phosphor belt

Abstract

The invention provides a light generating system (1000) comprising a light generating device (100) and a phosphor belt system (500), wherein: (I) the light generating device (100) comprises a solid state light source (10), wherein the solid state light source (10) is selected from the group of laser diodes and superluminescent diodes; wherein the light generating device (100) is configured to generate device light (101); (II) the phosphor belt system (500) comprises (i) n rotators (510), wherein n≥2, (ii) a belt element (520), and (iii) an actuator (540); wherein the actuator (540) is configured to rotate the belt element (520) about the rotators (510), wherein each rotator (510) comprises a rotation surface (511); (III) the belt element (520) comprises (a) a belt arrangement (530) comprising an internal surface (531), and (b) a luminescent material (200) having a luminescent material surface area (LMSA); wherein at least two of the rotators (510) is partly in contact with the internal surface (531) of the belt arrangement (530); and wherein the luminescent material (200) is configured to convert at least part of the device light (101) received by the luminescent material (200) into luminescent material light (201); and (IV) the light generating system (1000) is configured to generate in an operational mode of the light generating system (1000) system light (1001) comprising one or more of the device light (101) and the luminescent material light (201).

Description

[0001] Laser-based high-brightness light sources using phosphor belt

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system.

[0004] BACKGROUND OF THE INVENTION

[0005] Laser-phosphor based stage lighting is known in the art. For instance, US2013021582 (Al) describes an illuminating device for emitting light onto a light modulating element that forms an image in accordance with a modulation signal and irradiates a target to be illuminated with light, the illuminating device includes a substrate on which equal to or more than two phosphors that emit light with exciting light are formed in a band-like form along a predetermined direction, equal to or more than two light collecting units that are arranged for the respective equal to or more than two phosphors, and collect light components emitted from the respective equal to or more than two phosphors, and a driving unit that drives the substrate in the predetermined direction.

[0006] CN107688273A discloses a display system with a light source device that comprises an excitation light source and a wavelength conversion device, and the wavelength conversion device periodically moves relative to the excitation light source so that different areas of the wavelength conversion device are periodically illuminated by the excitation light source. The wavelength conversion device at least includes a first area, a second area and a third area that emit different colors of light. The control device controls a light modulator to perform image modulation according to the corresponding light modulation signal during the period when the wavelength conversion device emits corresponding colored light.

[0007] SUMMARY OF THE INVENTION

[0008] High brightness light sources can be used in various applications including spots, stage-lighting, headlamps, home and office lighting, and automotive lighting. For this purpose, laser-phosphor technology can be used, wherein a laser may provide laser light and a remote phosphor converts laser light into converted light. A problem with high intensity light sources in combination with the application of luminescent materials may be the thermal stability and / or the temperature dependence of the luminescence of the luminescent material. Yet, it appears desirable to provide such tunable lighting device which is able to provide the light with a high intensity. Further, there is a desire for color tunable lighting devices and / or lighting devices.

[0009] 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 an objective to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0010] In a first aspect, the invention provides a light generating system comprising a light generating device and a phosphor belt system. In embodiments, the light generating device may comprise a solid state light source. Especially, the solid state light source may be selected from the group of laser diodes and superluminescent diodes. Further, in embodiments, the light generating device may be configured to generate device light. In embodiments, the phosphor belt system may comprise n rotators, especially n>2. Further, in embodiments, the phosphor belt system may comprise a belt element and an actuator. Especially, the actuator may be configured to rotate the belt element about the rotators. In embodiments, each rotator may comprise a rotation surface. In embodiments, the belt element may comprise: (a) a belt arrangement comprising an internal surface, and (b) a luminescent material having a luminescent material surface area (LMSA). In embodiments, at least two of the rotators may be partly in contact with the internal surface of the belt arrangement. Further, in embodiments, the luminescent material may be configured to convert at least part of the device light received by the luminescent material into luminescent material light. In further embodiments, the light generating system may be configured to generate (in an operational mode of the light generating system) system light comprising one or more of the device light and the luminescent material light. In specific embodiments, the invention provides a light generating system comprising a light generating device and a phosphor belt system, wherein: (I) the light generating device comprises a solid state light source, wherein the solid state light source is selected from the group of laser diodes and superluminescent diodes; wherein the light generating device is configured to generate device light; (II) the phosphor belt system comprises (i) n rotators, wherein n>2, (ii) a belt element, and (iii) an actuator; wherein the actuator is configured to rotate the belt element about the rotators, wherein each rotator comprises a rotation surface; (III) the belt element comprises (a) a belt arrangement comprising an internal surface, and (b) a luminescent material having a luminescent material surface area (LMSA); wherein at least two of the rotators is partly in contact with the internal surface of the belt arrangement; wherein the luminescent material is configured to convert at least part of the device light received by the luminescent material into luminescent material light; and (IV) the light generating system is configured to generate in an operational mode of the light generating system “system light” comprising one or more of the device light and the luminescent material light. The light generating system is configured such that the device light is directed to part of the belt element at a location where the internal surface of the belt arrangement is configured in contact with one of the guiding elements, and / or wherein one or more of the guiding elements and the belt arrangement comprise a thermally conductive material.

[0011] With the present invention, a belt (comprised by the phosphor belt system) may comprise a luminescent material and may move under the moving action of e.g. multiple cylinders (i.e., rotators). In such a configuration, the length over which the luminescent material is coated (over the belt) may not be limited by the circumference of the cylinders (i.e., rotators), but may instead be determined by the length of the belt which may be relatively long (for example: longer than the sum of the circumferences of the rotators). In this way, the effective area over which the luminescent material may be pumped with device light may be relatively large which may be increased to improve cooling (of the light generating system). Further, such a light generating system may have improved mechanical stability relative to prior art system. Hence, such a system may be used in providing high lumen-output and high-intensity light for various applications such as projection and stagelighting, among other applications. Hence, in this way, the invention may provide amongst others a laser-based high-brightness light source(s) using a phosphor belt. Moreover, a plurality of luminescent materials may be configured on (or within) the belt, which may be used to tune or control the spectral properties of the generated light, thereby providing color tunability.

[0012] As mentioned above, the light generating system may comprise a light generating device and a phosphor belt system. Here below, some general aspects of the light generating system are described.

[0013] In embodiments, the light generating device may be configured to generate device light. Especially, during an operational mode, the device light may be incident on the belt element during operation of the light generating system.

[0014] In embodiments, the light generating device may comprise a solid state light source. Especially, the solid state light source may be selected from the group of laser diodes and superluminescent diodes. A light generating device may especially be configured to generate device light. Especially, the light generating device may comprise a light source. The light source may especially be configured to generate light source light. In embodiments, the device light may essentially consist of the light source light. The term “light generating device” may also refer to a plurality of light generating devices which may provide device light having essentially the same spectral power distributions. In (other) specific embodiments, the term “light generating device” may also refer to a plurality of light generating devices which may provide device light having different spectral power distributions.

[0015] The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a laser diode, a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser (EEL), a photonic crystal surface emitting laser (PCSEL), a vertical external cavity surface emitting laser (VECSEL), etc... The term “light source” may also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid-state light source (such as an LED or laser diode). In an embodiment, the light source comprises an LED (light emitting diode). The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED). The term LED may also refer to a plurality of LEDs. The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 solid state light sources. In embodiments, the light source may comprise one or more micro- optical elements (array of micro lenses) downstream of a single solid-state light source, such as an LED, or downstream of a plurality of solid-state light sources (i.e. e.g. shared by multiple LEDs. The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from the same bin.

[0016] The term “solid state light source”, or “solid state material light source”, and similar terms, may especially refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, or a superluminescent diode. The term “laser light source” especially refers to a laser. Such laser may especially be configured to generate laser light source light having one or more wavelengths in the UV, visible, or infrared, especially having a wavelength selected from the spectral wavelength range of 200-2000 nm, such as 300-1500 nm. The term “laser” especially refers to a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Especially, in embodiments the term “laser” may refer to a solid-state laser. In specific embodiments, the terms “laser” or “laser light source”, or similar terms, refer to a laser diode (or diode laser).

[0017] Hence, in embodiments the light source comprises a laser light source. In embodiments, the terms “laser” or “solid state laser” or “solid state material laser” may refer to one or more of cerium doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), chromium doped chrysoberyl (alexandrite) laser, chromium ZnSe (CrZnSe) laser, divalent samarium doped calcium fluoride (Sm:CaF2) laser, Er:YAG laser, erbium doped and erbium-ytterbium codoped glass lasers, F-Center laser, holmium YAG (Ho:YAG) laser, Nd:YAG laser, NdCrYAG laser, neodymium doped yttrium calcium oxoborate Nd:Yca4O(BO3)3 or Nd:YCOB, neodymium doped yttrium orthovanadate (Nd:YVO4) laser, neodymium glass (Nd:glass) laser, neodymium YLF (Nd:YLF) solid-state laser, promethium 147 doped phosphate glass (147Pm3+:glass) solid-state laser, ruby laser (AhO3:Cr3+), thulium YAG (Tm:YAG) laser, titanium sapphire (Ti:sapphire; AhO3:Ti3+) laser, trivalent uranium doped calcium fluoride (U:CaF2) solid-state laser, Ytterbium doped glass laser (rod, plate / chip, and fiber), Ytterbium YAG (Yb:YAG) laser, Yb2Os (glass or ceramics) laser, etc. For instance, including second and third harmonic generation embodiments, the light source may comprise one or more of an F center laser, an yttrium orthovanadate (Nd:YVO4) laser, a promethium 147 doped phosphate glass (147Pm3+:glass), and a titanium sapphire (Ti:sapphire; AhO3:Ti3+) laser. For instance, considering second and third harmonic generation, such light sources may be used to generated blue light.

[0018] In embodiments, the terms “laser” or “solid state laser” or “solid state material laser” may refer to one or more of a semiconductor laser diodes, such as GaN, InGaN, AlGalnP, AlGaAs, InGaAsP, lead salt, vertical cavity surface emitting laser (VCSEL), quantum cascade laser, hybrid silicon laser, etc.

[0019] A laser may be combined with an upconverter in order to arrive at shorter (laser) wavelengths. For instance, with some (trivalent) rare earth ions upconversion may be obtained or with non-linear crystals upconversion can be obtained. Alternatively, a laser can be combined with a downconverter, such as a dye laser, to arrive at longer (laser) wavelengths.

[0020] As can be derived from the below, the term “laser light source” may also refer to a plurality of (different or identical) laser light sources. In specific embodiments, the term “laser light source” may refer to a plurality N of (identical) laser light sources. In embodiments, N=2, or more. In specific embodiments, N may be at least 5, such as especially at least 8. In this way, a higher brightness may be obtained. In embodiments, laser light sources may be arranged in a laser bank (see also above). The laser bank may in embodiments comprise heat sinking and / or optics e.g. a lens to collimate the laser light. Hence, in embodiments lasers in a laser bank (or “laser array bank”) may share the same optics. The laser light source is configured to generate laser light source light (or “laser light”). The light source light may essentially consist of the laser light source light. The light source light may also comprise laser light source light of two or more (different or identical) laser light sources. For instance, the laser light source light of two or more (different or identical) laser light sources may be coupled into a light guide, to provide a single beam of light comprising the laser light source light of the two or more (different or identical) laser light sources. In specific embodiments, the light source light is thus especially collimated light source light. In yet further embodiments, the light source light is especially (collimated) laser light source light. The laser light source light may in embodiments comprise one or more bands, having band widths as known for lasers. In specific embodiments, the band(s) may be relatively sharp line(s), such as having full width half maximum (FWHM) in the range of less than 20 nm at RT, such as equal to or less than 10 nm. Hence, the light source light has a spectral power distribution (intensity on an energy scale as function of the wavelength) which may comprise one or more (narrow) bands.

[0021] The beams (of light source light) may be focused or collimated beams of (laser) light source light. The term “focused” may especially refer to converging to a small spot. This small spot may be at the discrete converter region, or (slightly) upstream thereof or (slightly) downstream thereof. Especially, focusing and / or collimation may be such that the cross-sectional shape (perpendicular to the optical axis) of the beam at the discrete converter region (at the side face) is essentially not larger than the cross-section shape (perpendicular to the optical axis) of the discrete converter region (where the light source light irradiates the discrete converter region). Focusing may be executed with one or more optics, like (focusing) lenses. Especially, two lenses may be applied to focus the laser light source light. Collimation may be executed with one or more (other) optics, like collimation elements, such as lenses and / or parabolic mirrors. In embodiments, the beam of (laser) light source light may be relatively highly collimated, such as in embodiments <2° (FWHM), more especially <1° (FWHM), most especially <0.5° (FWHM). Hence, <2° (FWHM) may be considered (highly) collimated light source light. Optics may be used to provide (high) collimation (see also above). The term “solid state material laser”, and similar terms, may refer to a solid state laser like based on a crystalline or glass body dopes with ions, like transition metal ions and / or lanthanide ions, to a fiber laser, to a photonic crystal laser, to a semiconductor laser, such as e.g. a vertical cavity surface-emitting laser (VCSEL), etc. The term “solid state light source”, and similar terms, may especially refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, or a superluminescent diode.

[0022] Instead of the term “solid state light source” also the term “semiconductorbased light source” may be applied. Hence, the term “semiconductor-based light source” may e.g. refer to one or more of a light emitting diode (LED), a laser diode, and a superluminescent diode. Hence, the light generating device may comprise one or more of a light emitting diode (LED), a laser diode, and a superluminescent diode.

[0023] Superluminescent diodes are known in the art. A superluminescent diode may be indicated as a semiconductor device which may be able to emit low-coherence light of a broad spectrum like an LED, while having a brightness in the order of a laser diode. US2020192017 indicates for instance that “With current technology, a single SLED is capable of emitting over a bandwidth of, for example, at most 50-70 nm in the 800-900 nm wavelength range with sufficient spectral flatness and sufficient output power. In the visible range used for display applications, i.e. in the 450-650 nm wavelength range, a single SLED is capable of emitting over bandwidth of at most 10-30 nm with current technology. Those emission bandwidths are too small for a display or projector application which requires red (640 nm), green (520 nm) and blue (450 nm), i.e. RGB, emission”. Further, superluminescent diodes are amongst others described, in “Edge Emitting Laser Diodes and Superluminescent Diodes”, Szymon Stanczyk, Anna Kafar, Dario Schiavon, Stephen Najda, Thomas Slight, Piotr Perlin, Book Editor(s): Fabrizio Roccaforte, Mike Leszczynski, First published: 03 August 2020 https: / / doi.org / 10.1002 / 9783527825264.ch9 in chapter 9,3 superluminescent diodes. This book, and especially chapter 9.3, are herein incorporated by reference. Amongst others, it is indicated therein that the superluminescent diode (SLD) is an emitter, which combines the features of laser diodes and light-emitting diodes. SLD emitters utilize the stimulated emission, which means that these devices operate at current densities similar to those of laser diodes. The main difference between LDs and SLDs is that in the latter case, the device waveguide may be designed in a special way preventing the formation of a standing wave and lasing. Still, the presence of the waveguide ensures the emission of a high- quality light beam with high spatial coherence of the light, but the light is characterized by low time coherence at the same time” and “Currently, the most successful designs of nitride SLD are bent, curved, or tilted waveguide geometries as well as tilted facet geometries, whereas in all cases, the front end of the waveguide meets the device facet in an inclined way, as shown in Figure 9.10. The inclined waveguide suppresses the reflection of light from the facet to the waveguide by directing it outside to the lossy unpumped area of the device chip". Hence, an SLD may especially be a semiconductor light source, where the spontaneous emission light is amplified by stimulated emission in the active region of the device. Such emission is called “super luminescence”. Superluminescent diodes combine the high power and brightness of laser diodes with the low coherence of conventional lightemitting diodes. The low (temporal) coherence of the source has advantages that the speckle is significantly reduced or not visible, and the spectral distribution of emission is much broader compared to laser diodes, which can be better suited for lighting applications. Especially, with varying electrical current, the spectral power distribution of the superluminescent diode may vary. In this way the spectral power distribution can be controlled, see e.g. also Abdullah A. Alatawi, et al., Optics Express Vol. 26, Issue 20, pp. 26355-26364, https: / / doi.org / 10.1364 / QE.26.026355. Hence, a superluminescent diode may be indicated as a semiconductor device which may be able to emit low-coherence light of a broad spectrum like a LED, while having a brightness in the order of a laser diode. Superluminescent diodes may combine the high power and brightness of laser diodes with the low coherence of conventional light-emitting diodes. The low (temporal) coherence of the source has advantages that the speckle is significantly reduced or not visible, and the spectral distribution of emission is much broader compared to laser diodes, which can be better suited for lighting applications. Hence, in embodiments, the solid state light source may comprise a superluminescent diode. For instance, in further specific embodiments, the solid state light source may comprise a GaN-based superluminescent diode, or an InGaN-based superluminescent diode, or an AlGaN-based superluminescent diode.

[0024] In specific embodiments, the device light may be blue light. 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). However, intensity at shorter wavelengths may also be possible, such as within the wavelength range of 400-440 nm. In specific embodiments, the device light may have a centroid wavelength (Xci) selected from the 400-490 nm wavelength range, more especially from the 400-480 nm wavelength range. Especially, in embodiments the device light has a peak wavelength selected from the blue wavelength range. The term “centroid wavelength”, also indicated as Xc, 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 Xc = X X*I(X) / (X I( X)), where the summation is over the wavelength range of interest, and I(X) 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.

[0025] The light generating system may in embodiments comprise the phosphor belt system. In embodiments, the phosphor belt system may comprise a belt element, a rotator, and an actuator. Here below, features of the phosphor belt system are described.

[0026] In embodiments, the rotator may be attached to an actuator (and may be configured to rotate). Especially, the actuator may be configured to rotate the rotator (about a rotational axis (AR)) at a predetermined torque and angular velocity. Especially, the belt may be rotated with a (linear) speed selected from the range of 0.1-100 m / s, such as 0.5-50 m / s, especially 2-30 m / s, more especially 5-20 m / s. The actuator may be configured to rotate one of the rotators, or two or more. In general, actuation of one of the rotators may already be enough to rotate the belt arrangement (e.g. directly via the frictional force due to surface contact). However, it may also be possible that the actuator actuates the belt element via engagement elements for a gear (directly, or via one or more rotators).

[0027] In embodiments, the rotator may (in a plane perpendicular to the rotational axis (AR)) have a circular cross-sectional shape. However, in embodiments, the rotator may also have other cross-sectional shapes such as a pentagon, a hexagon, a polygon, etc. Further, in embodiments, each rotator may comprise a rotation surface. Especially, the rotation surface may be the external surface of the rotator that is parallel to (and surrounding) the rotational axis (AR).

[0028] The system may comprise a plurality of rotators, especially i.e. n rotators, wherein n may be at least two. In further embodiments, n may be selected from the range 2- 10, such as 2-5, especially 2-3. Furthermore, in embodiments, n may be at maximum 20, such as at maximum 10. Note that a longer belt element may especially be accommodated by increasing the separation between the two (farthest located) rotators. Note also that the rotators may in embodiments not necessarily be of the same size. That is, in embodiments, each of the one or more rotators may differ in their cross-sectional shape and / or equivalent circular diameter (ECD). The equivalent circular diameter (or ECD) (or “circular equivalent diameter”) of an (irregularly shaped) two-dimensional shape is the diameter of a circle of equivalent area. For instance, the equivalent circular diameter of a square with side a is 2*a*SQRT( 1 / n). For a circle, the diameter is the same as the equivalent circular diameter. Would a circle in an xy -plane with a diameter D be distorted to any other shape (in the xy- plane), without changing the area size, then the equivalent circular diameter of that shape would be D. The rotators may be selected from elongate rotators, like cylinders, or relatively planar rotators, like wheel-shaped rotators.

[0029] In embodiments, the belt element may comprise a belt arrangement comprising an internal surface and a luminescent material. The belt element may comprise a plurality of (connected) sub-elements which may be arranged as defined by the belt arrangement. Especially, the belt arrangement may comprise a belt and the luminescent material associated with the belt. Further, in embodiments, the belt arrangement may comprise an external surface (and an internal surface). In further embodiments, the belt arrangement may comprise a belt, the internal surface, the external surface, and the luminescent material. In embodiments, the luminescent material may be configured on at least part of the belt. Especially, the luminescent material may be configured on one or more of the internal surface, the external surface, and within the belt.

[0030] In embodiments, the belt element may be configured over (and in contact with) at least part of the one or more rotators. In embodiments, one or more rotators may be partly in contact with the internal surface of the belt arrangement. Additionally or alternatively, the one or more rotators may be partly in contact with the external surface of the belt arrangement. Especially, however, one or more rotators may be partly in contact with at least the internal surface of the belt arrangement.

[0031] The belt element may in embodiments be driven by the rotation of the rotators. Especially, the actuator may be configured to rotate the belt element (i.e., in specific embodiments the actuator may be configured to rotate the rotator and thereby rotate the belt element).

[0032] Further, in embodiments, the light generating system may comprise one or more guiding elements to facilitate the rotation of the belt element about the rotators. The guiding elements may in embodiments at least comprise the rotators and may further optionally comprise one or more optional stationary guiding elements.

[0033] Note that, in embodiments, the light generating system may comprise at least one actuator. Further, in embodiments, the light generating system may comprise one or more rotators not associated with the actuator. Hence, one or more rotators (not associated with the actuator) may especially (only) facilitate the guiding of the belt element around the rotators. In embodiments, the belt element may be configured around two rotators such that about 50% of the rotational surface of each rotator may be in contact with the internal surface. The belt element may be configured around at least three rotators, wherein in specific embodiments rotation axes of at least three rotators are not in the same plane.

[0034] The rotators may have a width essentially the same as the width (Wl) of the belt element. Assuming the rotators to have rotator widths (W2), W1 / W2 may be selected from the range of about 0.9- 1.2, such as about 1-1.1, like e.g. 1.01-1.05. However, it may also be possible that one or more rotators have a much larger rotator width (W2), allowing the belt element to be wrapped around the rotator one or more times. This may further increase the length of the belt element, and thus also the luminescent material surface area. Hence, in embodiments the belt element is partly wrapped around one or more of the rotators over an angle a of at maximum 180°. In other embodiments, however, the belt element may be wrapped around at least one of the rotators one or more times over an angle a of 360°.

[0035] The use of additional rotators may especially facilitate (i) maintaining tension in the belt element, (ii) increase the area of contact with the external surface (or the internal surface), and (iii) load distribution; all of which may improve power transmission and prevent the belt element from slipping.

[0036] Furthermore, in embodiments the light generating system may comprise one or more optional stationary guiding elements such as rails, supports, guides, etc. These guiding elements may facilitate supporting the belt element. In specific embodiments, during operation of the phosphor belt system the internal surface of the belt arrangement may partly be configured in contact with one or more guiding elements, wherein the guiding elements comprise the rotators and one or more optional stationary guiding elements. The guiding elements provide additional mechanical stability and remove (any) slack in the belt element. Note that the rotators may also be considered guiding elements. Hence, two or more guiding elements may be rotatable and other guiding elements may be rotatable or stationary. For instance, a guiding element may be a stationary plate or curved feature, over which the belt arrangement may propagate.

[0037] Additionally, the one or more guiding elements and the belt arrangement may in embodiments facilitate cooling of the light generating device. In embodiments, the one or more of the guiding elements and the belt arrangement may comprise a thermally conductive material. In further embodiments, the one or more rotators may also comprise a thermally conductive material. Especially, the phosphor belt system may be configured such that the device light is incident upon the part of the belt element (that is also) in contact with one or more guiding elements. Hence, in this way, heat may especially be conducted away from the luminescent material via one or more of the guiding elements, and the belt arrangement. Therefore, in embodiments the belt arrangement may locally be at one side in contact with a guiding element, and another side of the belt arrangement, opposite of the part in contact with a guiding element, may receive the device light.

[0038] Further, at least part of the light generating system may in embodiments be (actively) cooled by flowing a gas over the belt arrangement. In embodiments, the light generating system may comprise a gas flow based cooling system. Especially, the light generating system may be configured such that the gas flow based cooling system may be configured to cool at least part of the belt element (during the operation of the light generating system). The gas flow based cooling system may in embodiments comprise one or more gas flow nozzles. Especially, the one or more nozzles may be directed to the external surface and or internal surface of the belt arrangement. Alternatively, or additionally, the gas flow based cooling system may cool at least part of the belt arrangement that receives the device light. Hence, in embodiments a gas flow may be directed to the illuminated spot on the belt arrangement that during operation is irradiated with the device light. Hence, in this way, heat from the belt element may especially be removed from the light generating system by means of convection. Hence, in specific embodiments, the light generating system further comprises a gas flow based cooling system, wherein the light generating system is configured such that the gas flow based cooling system is configured to cool at least part of the belt element at a location where during operation of the light generating device, the belt element receives device light. The part (or region) of the belt element upon which device light is incident may have a (significantly) higher temperature as compared to other parts of the belt element. Hence, in (other) embodiments, the gas flow based cooling system may direct cooling gas on the part of the belt element in contact with one or more guiding elements to facilitate cooling by means of convection. Other cooling elements, not based on a gas flow, may also be applied, like e.g. Peltier cooling of a rotator or stationary guiding element, or water cooling of a rotator or stationary guiding element.

[0039] In embodiments, the belt element may at least partly surround the light generating device and hence the light generating device may illuminate the belt element via the internal surface of the belt arrangement. Alternatively, in embodiments, the light generating device may be positioned such that the light generating device is configured external to the belt element. Thus, the light generating device may illuminate the belt element via the external surface of the belt arrangement (or optionally via the internal surface of the belt arrangement). In further embodiments, the light generating system may comprise a plurality of light generating devices, wherein the belt element may be illuminated with device light incident on the external surface and / or the internal surface.

[0040] In embodiments, the light generating system may comprise one or more additional optical elements. Especially, the optical elements may beam shape the device light or direct the device light to a particular position on the belt element (for instance to irradiate the luminescent material). However, optical element may also be used to combine beams. In embodiments, one or more (additional) optical elements may be selected from the group of reflectors, (curved) reflectors, diffusers, lenses, prisms, polarizers, beam splitters, and dichroic filters.

[0041] As mentioned above, the luminescent material may especially be configured to convert at least part of the device light incident on the luminescent material into luminescent material light.

[0042] The term “luminescent material” especially refers to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation. In general, the first radiation and second radiation have different spectral power distributions. Hence, instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” may be applied. In embodiments, the “luminescent material” may especially refer to a material that can convert radiation into e.g. visible and / or infrared light. For instance, in embodiments the luminescent material may be able to convert one or more of UV radiation and blue radiation, into visible light. The luminescent material may in specific embodiments also convert radiation into infrared radiation (IR). Hence, upon excitation with radiation, the luminescent material emits radiation. In general, the luminescent material will be a down converter, i.e. radiation of a smaller wavelength is converted into radiation with a larger wavelength (Xex<Xem), though in specific embodiments the luminescent material may comprise up-converter luminescent material, i.e. radiation of a larger wavelength is converted into radiation with a smaller wavelength (Xex>Xem).

[0043] In embodiments, the term “luminescence” may refer to phosphorescence. In embodiments, the term “luminescence” may also refer to fluorescence. Instead of the term “luminescence”, also the term “emission” may be applied. Hence, the terms “first radiation” and “second radiation” may refer to excitation radiation and emission (radiation), respectively. Likewise, the term “luminescent material” may in embodiments refer to phosphorescence and / or fluorescence. The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition. Instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art.

[0044] In specific embodiments the luminescent material comprises a luminescent material of the type AsBsOnT'e. wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, especially (at least) one or more of Y, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc. Especially, A may comprise one or more of Y, Gd and Lu, such as especially one or more of Y and Lu. Especially, B may comprise one or more of Al and Ga, more especially at least Al, such as essentially entirely Al. Hence, especially suitable luminescent materials are cerium comprising garnet materials. Embodiments of garnets especially include A3B5O12 garnets, wherein A comprises at least yttrium or lutetium and wherein B comprises at least aluminum. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B may comprise aluminum (Al); however, in addition to aluminum, B may also partly comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), especially up to about 20% of B, more especially up to about 10 % of B (i.e. the B ions essentially consist of 90 or more mole % of Al and 10 or less mole % of one or more of Ga, Sc and In); B may especially comprise up to about 10% gallium. In another variant, B and O may at least partly be replaced by Si and N. The element A may especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and / or Tb are especially only present up to an amount of about 20% of A. In a specific embodiment, the garnet luminescent material comprises (Yi-xLux)3BsOi2: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)3AlsOi2:Ce, part ofY 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.

[0045] In embodiments, the luminescent material may have an excitation band, especially in the blue wavelength range, at least partly overlapping with a device light emission band. This may apply to essentially any luminescent material used herein, though embodiments wherein one luminescent material is excited by the emission of another luminescent material are not excluded.

[0046] In embodiments, the luminescent material may comprise a first luminescent material configured to convert a part of the device light into first luminescent material light. Additionally, in embodiments, the luminescent material may comprise a second luminescent material configured to convert a part of the device light into second luminescent material light. Especially, the first luminescent material light and the second luminescent material light may especially have different spectral power distributions. Furthermore, in embodiments, the luminescent material may comprise a plurality of different luminescent materials each with a different spectral power distribution (upon excitation with the device light). Hence, the first luminescent material light and the second luminescent material light may have different color points.

[0047] 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’. Here, u’ and v’ are color coordinates of the light in the CIE 1976 UCS (uniform chromaticity scale) diagram.

[0048] In embodiments, the belt arrangement may comprise either the first luminescent material or both the first luminescent material and the second luminescent material. In further embodiments, the belt arrangement may comprise a plurality of different luminescent materials. Especially, when applying different luminescent materials, they may be configured separated in the belt arrangement. Note however that the term “luminescent material” may also refer to a mixture of different luminescent materials.

[0049] In embodiments, the belt element may comprise a continuous or a segmented belt. In embodiments (wherein the belt is continuous), the luminescent material may be distributed continuously over the (at least a part of the) external surface and / or (at least a part of) the internal surface of the belt arrangement. The term “continuously” may refer to a lack of gaps or interruptions i.e., a line may be traced along the entire length of the belt back to the starting point without any breaks. In contrast, “segmented” may refer to a plurality of distinct independent units configured at a certain distance between each segment. Note that, in embodiments, the belt element may be continuous i.e., the belt may be a single continuous loop. Alternatively, in embodiments, the belt (comprised by the belt element) may comprise segments that may connected to form a loop.

[0050] Note that, the luminescent material may in embodiments also be configured on the internal surface, or external surface or within the belt such that the luminescent material is distributed continuously through (at least a part ol) the belt. Alternatively, in embodiments, the luminescent material may be configured discontinuously in individual parts along the length of the belt. In some embodiments, the belt element may be segmented, and luminescent material may be configured in one or more of these segments of the belt element. However, in other embodiments, the belt element may be continuous and yet the luminescent material may be configured discontinuously as different parts along the length of the belt.

[0051] In embodiments, the different segments comprised by the belt arrangement may comprise either the first luminescent material or the second luminescent material. In specific embodiments, the luminescent material comprises (i) a first luminescent material configured to convert at least part of the device light reaching the first luminescent material into first luminescent material light and (ii) a second luminescent material configured to convert at least part of the device light reaching the second luminescent material into second luminescent material light, wherein the first luminescent material light and the second luminescent material light have different spectral power distributions; wherein the first luminescent material and the second luminescent material are comprised by different parts of the belt arrangement. Hence, in embodiments these different parts may be on the same segment, on different segments, or on the same continuous belt arrangement.

[0052] In embodiments, the one or more luminescent materials may be configured in the belt element in a plurality of different configurations. In embodiments, the one or more luminescent material may be configured in parallel tracks running along the length of the belt element. Especially, the parallel tracks of the luminescent material may be configured perpendicular to the rotational axis (OR). Alternatively, in embodiments, the one or more luminescent materials may be configured in a direction along the length of the belt in an alternating configuration along the belt. For instance, along the length of the belt element, the first luminescent material may be followed by the second luminescent material, and so on. Yet further, in embodiments, the first luminescent material may be configured under the second luminescent material, and vice versa.

[0053] Further, in embodiments, the belt may comprise a groove (on the internal surface and / or the external surface), wherein the luminescent material may be configured within said groove. In further embodiments, the belt may comprise a plurality of grooves, wherein the luminescent material may be configured within the one or more grooves. The grooves may especially facilitate configuring the luminescent material such that the luminescent material does not protrude from the internal or external surface. In this way, the belt element may rotate about the rotators without incurring any damage to the luminescent material configured within the grooves. Hence, in embodiments when applying two different luminescent materials, they may be configured in two parallel configured grooves.

[0054] Note that the aforementioned configurations are not limited to only luminescent material. In embodiments, optical elements such as reflectors and diffusers may also be configured in place of (or in addition to) one or more of the luminescent materials. For instance, in embodiments, the optical elements may be configured as parallel tracks along the length of the belt element or may be configured in alternating configuration with one or more luminescent material. In specific embodiments, the belt arrangement further comprises a reflective part, configured to reflect at least part of the device light received by the reflective part, to provide reflected device light; wherein the luminescent material and the second luminescent material are comprised by different parts of the belt arrangement; wherein the light generating system is configured to provide in an operational mode of the light generating system, system light comprising averaged over time luminescent material light and reflected device light. Similarly, in embodiments, diffusers may scatter light incident on them and hence may provide diffuse lighting. Note that diffusers may especially (also) be provided by diluting the one or more luminescent materials.

[0055] Note that, in embodiments wherein the luminescent material is configured in a segmented configuration (separated by non-luminescent gaps), the incidence of device light on the luminescent material may be controlled by controlling the rotational speed of the belt element. Especially, the light generating device may be configured to operate in an operational mode at a frequency synchronized with the rotation of the belt element to prevent the incidence of device light on the non-luminescent gaps. In specific embodiments, the light generating system may be configured to sequentially irradiate the first luminescent material and the second luminescent material with the device light with a frequency of at least 50 Hz, such as at least 100 Hz, especially at least 200 Hz. In further embodiments, the light generating system may be configured to sequentially irradiate the first luminescent material and the second luminescent material with the device light with a frequency of at maximum 500 Hz, such as at maximum 400 Hz, especially at maximum 300 Hz.

[0056] In embodiments, the belt arrangement may comprise one or more metal parts. Especially, the luminescent material may be configured on at least one of the one or more metal parts. Especially, the one or more metal parts may be selected from the group of aluminum, silver, iron, and copper. Further, it will be apparent to the skilled person that any metal or alloy with thermally conductive properties may in embodiments be selected. In such embodiments, the luminescent material may be configured on the external surface of the belt arrangement and may be irradiated by device light incident on the external surface.

[0057] Especially, the luminescent material may be dispersed in a belt (comprised by the belt element). In such embodiments, the belt element may be transmissive for device light, and hence the belt element may be irradiated with device light incident on (or via) the external surface (and / or on (or via) the internal surface) (of the belt element). Hence, in embodiments the luminescent material may be embedded in the belt. Especially, the belt arrangement may comprise a silicone belt, wherein especially the luminescent material may be embedded.

[0058] Furthermore, in embodiments, the light generating system may be configured such that the device light is directed to part of the belt element at the location where the (local) internal surface of the belt arrangement is configured in (physical) contact with one of the guiding elements. With such an embodiment, a part of the device light may be reflected at an external surface of the guiding element and be reflected via the belt element, thus undergoing subsequent conversion to luminescent material light. Thereby, increasing the amount of (converted) luminescent material light provided by the light generating system. In (other) embodiments, the light generating system may be configured such that the device light is directed to part of the belt element at the location where the (local) external surface of the belt arrangement is configured in (physical) contact with one of the guiding elements. In this way, device light may be incident on a part of the belt element in contact with the guiding element and thereby, the bulk of the heat generated may be conducted away from the point of incidence of device light.

[0059] In embodiments, the belt arrangement may have a belt arrangement length (Li) selected from the range of 3-300 cm, such as in the range of 10-100 cm, especially in the range 20-100 cm. A longer belt arrangement may provide the advantage of increasing the surface area over which luminescent material may be configured. Furthermore, the increased surface area of the belt arrangement may increase the area over which heat may be distributed, thus improving cooling of the belt element. Further, in embodiments, the belt arrangement may have a width (Wi) measured along the rotational axis (AR). Especially, the width (Wi) of the belt may be selected from the range of 1-50 mm, such as 5-20 mm, especially 10-15 mm. In further embodiments, the luminescent material may be configured along a track on the belt.

[0060] Especially, the first luminescent material may be configured along a track (on the belt arrangement) and the second luminescent material may (also) be configured along a track (on the belt). In further embodiments, luminescent materials may be configured on a plurality of different tracks on the belt. Thereby, in embodiments, the spectral power distribution of the system light may be varied by varying the position at which the device light is incident on the belt element (i.e., on the first track and / or the second track). Hence, in specific embodiments, the belt arrangement has a belt arrangement width (Wi), wherein the first luminescent material and the second luminescent material are configured at different width positions, wherein the light generating system is configured such that a width position at the location where the device light is received, is controllable. Aspects in relation to controllability of the light generating system and different operational modes are discussed further below.

[0061] In embodiments, at any given instant during operation, the device light may be incident on a spot on the external surface (or in embodiments internal surface) of the belt element. The area of the illuminated spot on the external surface (or in embodiments internal surface) may be referred to as a spot size (SZ). The total area of the luminescent material irradiated by the device light over one complete rotation of the belt element may especially be referred to as the illumination area (IA).

[0062] In embodiments, the illumination area (IA) may at least be y times the spot size (SZ). Especially, y may be at least 10, such as at least 20, especially at least 30, more especially at least 40, more especially at least 50. In (other) embodiments, y may at maximum be 500,000, such as at maximum 100,000, especially at maximum 50,000. A relatively larger illumination area (IA) compared to the spot size (SZ) may facilitate distribution of heat over a larger area and hence improve thermal management (such as cooling) of the light generating system.

[0063] Further, the total surface area of the luminescent material comprised by the belt arrangement may be referred to as the luminescent material surface area (LMSA). In embodiments, the luminescent material surface area (LMSA) may at least be x times the illumination area (IA). Especially, x may at least be 2, such as at least 5, especially at least 10, more especially at least 20, like at least 25. In (other) embodiments, y may at maximum be 1,000, such as at maximum 500, especially at maximum 100. Therefore, in embodiments the luminescent material surface area (LMSA) may be is at least 2 times an illumination area (I A) of the device light on the luminescent material, wherein especially the illumination area (IA) of the device light on the luminescent material may be defined as a total area of the luminescent material surface area (LMSA) irradiated with the device light during a single rotation of the belt element by, during operation, the device light being incident on a spot on the external surface of the belt element wherein the area of the illuminated spot on the external surface is referred to as a spot size (SZ).

[0064] Note that in some embodiments, the device light may be incident on both the external surface as well as the internal surface, in which case the luminescent material surface area (LMSA) may in embodiments e.g. be twice a cross-sectional are of the luminescent material. Analogously, in such embodiments, the illumination area (IA) may (also) at least be twice the illumination area (IA) would the device light be incident on only the external surface or the internal surface. Note that, in embodiments, the position of the illuminated spot and / or size the spot size (SZ) may be controlled. Hence, in this way, the position and / or size of the illumination area (I A) may be varied over time. Therefore, a relatively larger luminescent material surface area (LMSA) compared to the illumination area (IA) may accommodate a plurality of different variations in the illumination area (IA).

[0065] The luminescent material surface area (LMSA) may in general be essentially the same as a cross-sectional area of the luminescent material. Note that there may be two or more luminescent configured parallel to each other. In such embodiments, the luminescent material surface area (LMSA) refers to the total luminescent material surface area (LMSA) of both luminescent materials.

[0066] In embodiments, the light generating system may be configured to generate in an operational mode of the light generating system “system light”. Especially, the system light may comprise luminescent material light and the device light. In embodiments, the spectral properties (especially, the spectral power distribution) of the system light provided by the light generating system may be varied in dependence of the mode of operation (or operational mode). In the operational mode wherein device light is only incident on a reflector (e.g. comprised in a reflector track, or reflective segment), the system light may essentially only comprise device light. In the operational mode wherein device light is only incident on the luminescent material, the system light may essentially comprise luminescent material light. In further embodiments, in an operational mode, the system may provide a combination of device light and luminescent material light. Note that in embodiments, the system may comprise the first luminescent material and the second luminescent material. Hence, in such embodiments, the system may in an operational mode provide: (i) device light and / or first luminescent material light, or (ii) device light and / or second luminescent material light, or (iii) device light and / or a combination of first luminescent material light and second luminescent material light. In embodiments, the spectral power distribution of the system light may be varied by controlling a position where the device light irradiates the belt element.

[0067] Further, in embodiments, the system light may be provided at a desired correlated color temperature (CCT) in combination with a desired color rendering index (CRI). The terms “CCT” or “CRI” herein, and similar terms, will be understood by the person skilled in the art. 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. The color rendering of the (white) system light may be at least 65, such as at least about 70. Hence, in specific embodiments, the system light comprises in an operational mode of the system white light having a correlated color temperature selected from the range of 1800-20000 K, and a color rendering index of at least 65, such as at least 70.

[0068] In embodiments, the one or more elements comprised by the light generating system, such as the light generating device, the actuators, etc. may be controlled by means of a control system. Hence, the control system may especially operate the light generating system in a mode of operation (or operational mode). In embodiments, the control system may control the rotation of the actuators. Especially, the torque and / or the angular velocity of the actuators may be controlled. Further, in embodiments, the control system may control the operation of the light generating system such as the frequency at which device light is emitted from the light generating device and / or the spot size (SZ) and / or the position of the illuminated spot. In embodiments, the control system may control the size of the spot size (SZ) and / or the position of the illuminated spot as a function of time. The control system may in embodiments control the position of the light generating device. The spot size (SZ) may especially be decreased when the light generating device is moved closer to the belt element, and vice versa.

[0069] Further, in embodiments, the spot size may be altered by means of one or more optical elements (for example a lens or a curved mirror) configured along the path of the device light. For example, the control system may alter the part of the belt element illuminated by device light by configuring a rotating conical prism between the belt element and the light generating device.

[0070] Furthermore, in embodiments the luminescent material may be configured in segments along the belt element. Hence, there may be gaps between two segments. Note that the device light may not be emitted continuously but at a predefined (flicker) frequency. In such embodiments, it may be an option to configure in an operational mode the angular velocity of the rotators to be synchronized with the frequency at which device light is emitted (or vice versa). Hence, in this way, at every moment that the device light is emitted, it may be incident on the luminescent material.

[0071] Not also that in embodiments wherein the luminescent material is configured in segments along the belt element, the total luminescent material surface area may be sum of the areas of the luminescent material comprised in each segment.

[0072] Additionally or alternatively, in embodiments, the control system may control the position of a beam of device light along the width of the belt element. This may be useful in embodiments comprising different regions or tracks on the belt arrangement that may be selectively irradiated by the device light. Thus, providing a color point adjustable system. Furthermore, in embodiments, the position of the belt arrangement may be locally controllable. Hence, in specific embodiments, one or more of the following applies: (a) a position of beam of device light is controllable, and (b) a position of the belt arrangement is at least locally controllable.

[0073] Furthermore, in embodiments, the control system may control the operation of the gas flow based cooling system. Especially, parameters of the gas flow based cooling system such as the pressure, flow-rate, temperature of the (cooling) gas may be controlled.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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. 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).

[0078] 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. In specific embodiments, inputs for such a control system may be, next to target setting signals or boundary signals, sensor signals, such as temperature-correlated signals, optical flux correlated signals, and / or optical flux ratio or color point correlated signals, etc.

[0079] In yet a further aspect, the invention also may provide 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 may provide 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 may provide a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support one or more of the first light generating device, second light generating device, and one or more of the aforementioned optics. The lighting device may also be an automotive lighting device, such as a headlamp (or headlight) of a motorized vehicle (like a car, a truck, a bus, a coach, a tractor, a boat, an airplane, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0080] 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:

[0081] Figs, la-d schematically depict some embodiments and aspects of the (embodiments of) the light generating system;

[0082] Fig. 2a-c schematically depict some (other) embodiments and (other) aspects of the belt arrangement 530; and

[0083] Fig. 3 shows an embodiment of the light generating system 1000.

[0084] Fig. 4 schematically depicts some application embodiments. The schematic drawings are not necessarily to scale.

[0085] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0086] Figs, la-d schematically depict some embodiments and aspects of the (embodiments ol) the light generating system 1000. First some general aspects of the light generating system 1000 are described followed by embodiments of the light generating system 1000.

[0087] In embodiments, the invention provides a light generating system 1000 comprising a light generating device 100 and a phosphor belt system 500. The light generating device 100 may in embodiments comprise a solid state light source 10. Especially, the solid state light source 10 may be selected from the group of laser diodes and superluminescent diodes. In embodiments, the light generating device 100 may be configured to generate device light 101. Especially, the device light 101 may comprise blue light.

[0088] In embodiments, the phosphor belt system 500 may comprise (i) n rotators

[0089] 510, (ii) a belt element 520, and (iii) an actuator 540. In further embodiments, n may be at least two. In further embodiments, n may be selected from the range 2-10, such as 2-5, especially 2-3. The actuator 540 may especially be configured to rotate the belt element 520 about the rotators 510. In embodiments, each rotator 510 may comprise a rotation surface

[0090] 511.

[0091] In embodiments, the belt element 520 may comprise (a) a belt arrangement 530 comprising an internal surface 531, and (b) a luminescent material 200 having a luminescent material surface area LMSA. Note that in embodiments, the belt arrangement 530 may (also) comprise an external surface 532. In further embodiments, the belt arrangement 530 may comprise a belt 535. The luminescent material surface area (LMSA) may in embodiments extend over (or within) at least part of the belt 535. Such embodiments are discussed further below, see Fig. 2a-c. In embodiments, the rotation surface 511 comprised by each rotator 510 may be partly in contact with the internal surface 531 (and optionally in contact with the external surface 532) of the belt arrangement 530.

[0092] In embodiments, the device light 101 may be incident (or may irradiate) a spot on the belt element 520. Especially, the device light 101 may be incident on the spot on the external surface 531 and / or the internal surface 532. The area of the illuminated spot, indicated with reference S, on the external surface may be referred to as spot size SZ. The total area of the luminescent material irradiated by the device light over one complete rotation of the belt element may especially be referred to as the illumination area IA. In embodiments, the illumination area IA may at least be y times the spot size SZ. Especially, y may be at least 10, such as at least 20, especially at least 30, more especially at least 40, more especially at least 50. Further, the total surface area of the luminescent material comprised by the belt arrangement may be referred to as the luminescent material surface area LMSA. In embodiments, the luminescent material surface area LMSA may at least be x times the illumination area IA. Especially, x may at least be 2, such as at least 5, especially at least 10, more especially at least 20, like at least 25. The spot size SZ, the illumination area I A and the luminescent material surface area LMSA are depicted in embodiment I of Fig. 2a.

[0093] Further, in embodiments, the luminescent material 200 may be configured to convert at least part of the device light 101 received by the luminescent material 200 into luminescent material light 201. In embodiments, the luminescent material 200 may comprise a luminescent material of the type AsBsOnT'e. wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc.

[0094] In embodiments, the luminescent material 200 may be configured on at least part of the belt 535. In embodiments, the belt arrangement 530 may have a belt arrangement length Li selected from the range of 3-300 cm, such as in the range of 10-100 cm, especially in the range 20-50 cm. The belt arrangement length Li is indicated in Fig. la by means of dashed lines. Further, in embodiments, the belt arrangement 530 may have a width Wi. Especially, the width Wi of the belt 535 may be selected from the range of 1-50 mm, such as 5-20 mm, especially 10-15 mm. In embodiments, belt element 520 may comprise a smooth continuous belt 535. In further embodiments, the belt element 520 may (also) comprise a cogged or ribbed belt 535. Furthermore, the one or more rotators 510 may (also) comprise analogous cogs and / or teeth to facilitate rotating the belt 535. In embodiments, the belt arrangement 530 may be configured to be in contact with one or more guiding elements 507. The guiding elements 507 may facilitate the guiding and the rotation of the belt element 520 around the rotators 510. Especially, the guiding element 507 may comprise the rotator 510. In further embodiments, the guiding elements 507 may (also) comprise one or more optional stationary guiding elements 508. The guiding elements 507 may in embodiments facilitate guiding (or rotating) the belt element 520 around the rotators 510.

[0095] Additionally, in embodiments, the one or more guiding elements 507 and the belt arrangement 530 may facilitate cooling of the light generating system 1000. In embodiments, the one or more guiding elements 507 and the belt arrangement 530 may comprise thermally conductive material. Hence, heat may be removed from the belt arrangement 530 by means of conduction. Typically, the part of the belt element 520 upon which the device light 101 is incident on may experience the highest temperature (compared to the rest of the belt element 520) and hence, in embodiments, the device light 101 may be configured to be incident upon a part of belt element 520 in contact with the guiding element 507.

[0096] In further embodiments, the light generating system 1000 may comprise a gas flow based cooling system 570. Especially, the light generating system 1000 may be configured such that the gas flow based cooling system 570 is configured to cool at least part of the belt element 520 at a location where during operation of the light generating device 100, the belt element 520 receives device light 101. Hence, the gas flow based cooling system 570 may flow a (cooling) gas over the belt arrangement 530 and thereby remove heat by means of convection. Especially, the gas flow based cooling system 570 may flow a (cooling) gas over the part of the belt element 520 at the location where the device light 101 is incident on the belt element 520.

[0097] For example, in a light generating device 100 comprising a laser with a spot size SZ of 1 mm2dissipating heat of 15 W / mm2in the phosphor (i.e., luminescent material 200) (with an average heat capacity of 0.75 J / kg) with a belt thickness of 0.2 mm on a rotator 510 with a diameter of 10 cm, rotating at 160 Hz (50000 mm / s), the temperature rise would be limited to 10°C. The temperature rise may be limited by the heat dissipation at high rotational frequencies which enables cooling (as compared to a slower speed such as 50 Hz wherein the temperature rise may be limited to 30°C). Further, forced convection (by means of the gas flow based cooling system 570) may especially facilitate the use of laser power dissipation densities. Considering a rotator with a diameter 10 cm, the belt element 520 with a length Li = 31.4 cm, may provide an average power density of 0.037 W / mm2

[0098] Further, in embodiments, the light generating system 1000 may be configured to generate in an operational mode of the light generating system 1000 system light 1001 comprising one or more the luminescent material light 201 and (optionally) the device light 101. In further embodiments, the system light 1001 may comprise a combination of both the device light 101 and the luminescent material light 201. Furthermore, in embodiments, the system light 1001 may comprise in an operational mode of the light generating system 1000 white light having a correlated color temperature selected from the range of 1800-20000 K, and a color rendering index of at least 65, such as at least about 70.

[0099] Fig. la schematically depicts an embodiment of the light generating system 1000. In the embodiment depicted, the phosphor belt system 500 comprises two rotators 510. In embodiments, during operation of the phosphor belt system 500, the internal surface 531 of the belt arrangement 530 may be partly configured in contact with the rotational surface 511. Hence, the belt element 520 comprising the belt 535 may be rotated by rotating the rotators 510. Especially, the belt element 520 may be rotated with a (linear) speed selected from the range of 0.1-100 m / s, such as 0.5-50 m / s, especially 2-30 m / s, more especially 5-20 m / s.

[0100] In embodiments, the two rotators 510 may be driven by two actuators 540. Alternatively, in embodiments, one of the rotators 510 may be driven by the actuator 540 and the other rotator 510 may facilitate the rotation of the belt element 520. Note that, the one or more rotators 510 may be indirectly driven by one or more actuators 540 by means of an additional belt, a chain, a cog, etc. (not shown in the figure). Further, in the embodiment depicted, one side (i.e., the internal surface 531) of the belt element 520 is supported by the stationary guiding element 508.

[0101] In embodiments, the light generating system 1000 may be configured such that the device light 101 is directed to part of the belt element 520 at the location where the (local) internal surface 531 of the belt arrangement 530 is configured in contact with one of the guiding elements 507 (for example on the left rotator 507). Therefore, in embodiments the belt arrangement 530 may locally be at one side (for example the internal surface 531) in contact with a guiding element 507, and another side of the belt arrangement 530 (for example the external surface 532), opposite of the part in contact with a guiding element 507, may receive the device light 101. In further embodiments, the device light 101 may also be incident on any (other) part of the belt element 520 (for example on the external surface 532 over the stationary guiding element 508). Hence, in embodiments, the device light 101 may be incident on one or more of (i) a part of the belt element 520 wherein the belt element 520 is in contact with the rotator 510, and (ii) a part of the belt element 520 supported by the guiding element 507. Especially, the guiding element 507 (which may also comprise the rotator 510) may also facilitate thermal management by conducting heat away from the belt element 520. In specific embodiments, the guiding element 507 may comprise a heat exchanger.

[0102] Fig. lb schematically depicts another embodiment of the light generating system 1000. The embodiment depicts an alternative configuration of the phosphor belt system 500 comprising three rotators 510. In embodiments, the belt element 520 of a longer length may be configured in the light generating system 1000 by configuring the two farthest rotators 510 further apart from one another. In further embodiments, the phosphor belt system 500 may comprise additional rotators 510 (for example one additional rotator 510 in the embodiment depicted) to support the belt element 520. Additionally, in such embodiments, (any) slack in the belt 535 may be removed. Such configurations facilitate improved cooling by increasing the surface area over which luminescent material 200 may be configured on the belt element 520. In the embodiment depicted, the light generating system 1000 comprises the gas flow based cooling system 570 configured to flow (or blow) a (cooling) gas on the belt arrangement 530. Especially, the gas flow based cooling system 570 may blow a (cooling) gas over the part of the belt arrangement 530 irradiated by device light 101.

[0103] Fig. 1c schematically depicts another embodiment of the light generating system 1000. In the depicted embodiment, the phosphor belt system 500 comprises three rotators 510. The rotation surface 511 of two of the rotators are in contact with a part of the internal surface 531 of the belt arrangement 530. Further, in the embodiment depicted, the rotation surface 511 of one of the rotators 510 is in contact with the external surface 532 of the belt arrangement 530. Furthermore, in embodiments, the one or more rotators 510 may have a unique diameter i.e., in the depicted embodiment, the rotator 510 configured between the two extreme rotators 510 has a comparatively smaller diameter. In this embodiment, the belt 535 is in contact with both the internal surface 531 and the external surface 532 of the belt arrangement 530.

[0104] Fig. Id schematically depicts an embodiment of the light generating system 1000. Particularly, the depicted embodiment illustrates a configuration of the phosphor belt system 500. In the embodiment depicted, the phosphor belt system 500 comprises two rotators 510. In further embodiments, the belt element 520 may be wrapped around one or more, such as at least two, of the rotators 510 multiple times. Such a configuration may accommodate a belt element 520 with a longer length, reduce / remove slack in the belt 535 and reduce slip between the rotators 510 and the belt element 520. Note that in embodiments the belt element 520 may be at least partly wrapped around one or more of the rotators 510 over an angle a of at maximum 180° (as indicated in Fig.la-lc). However, as depicted in this figure, the belt element 520 may be wrapped around at least one of the rotators 510 one or more times over (i.e., greater than) an angle a of 360°. Note also that, in such embodiments, the rotators 510 may have a width W2 significantly larger than the width Wi of the belt element 520, thus, accommodating the belt element 520 being wrapped around the rotator 510 multiple times.

[0105] Fig. 2a-c schematically depicts some (other) embodiments and (other) aspects of the belt arrangement 530. Note that, in embodiments, the belt arrangement 530 may comprise a plurality of luminescent materials 200, such as a first luminescent material 210 and a second luminescent material 220.

[0106] Furthermore, in embodiments, the belt arrangement 530 may comprise a reflective part 560, configured to reflect at least part of the device light 101 received by the reflective part 560, to provide reflected device light 101. Especially, the first luminescent material 210 and the second luminescent material 220 may be comprised by different parts of the belt 535. Thereby, in embodiments, the light generating system 1000 may be configured to provide in an operational mode of the light generating system 1000 system light 1001 comprising averaged over time luminescent material light 201 and reflected device light 101. Here below, different configurations of the belt arrangement 530 in embodiments are described.

[0107] Embodiment I in Fig. 2a depicts the first luminescent material 210 and the second luminescent material 220 configured as parallel tracks along the length of the belt 535. In Fig. 2a, the embodiment on the left depicts an overhead view of the belt arrangement 530, and on the right a cross-sectional view of the belt arrangement 530. Especially, the luminescent material 200 may comprise (i) a first luminescent material 210 configured to convert at least part of the device light 101 reaching the first luminescent material 210 into first luminescent material light 211 and (ii) a second luminescent material 220 configured to convert at least part of the device light 101 reaching the second luminescent material 220 into second luminescent material light 221. In embodiments, the first luminescent material light 211 and the second luminescent material light 221 may have different spectral power distributions.

[0108] Device light 101 may be incident on the first luminescent material 210 or the second luminescent material 220. The spot S indicates the region where the device light 101 is incident upon the belt element 520. The spot S has a spot size or area SZ. During operation, the belt element 520 may rotate about the rotators 510 and hence a region (or track) along the belt element 520 may undergo irradiation. The total irradiated or total illuminated area may be referred to as the illumination area IA and is indicated by dashed lines. Note that in this embodiment, luminescent material 200 is configured along two tracks. In this embodiment, the luminescent material surface area LMSA is the total sum of the area over which the first luminescent material 210 and the second luminescent material 220 are provided.

[0109] Furthermore, the belt arrangement 530 may especially have a belt arrangement width Wi such that the first luminescent material 210 and the second luminescent material 220 are configured at different width positions. Hence, by controlling the width position at the location where the device light 101 is received, the composition of system light 1001 (comprising first luminescent material light 211 and the second luminescent material light 221) may be varied.

[0110] In the depicted embodiment I, the first luminescent material 210 and the second luminescent material 220 are configured on different parts of the belt 535. That is, the belt arrangement 530 has a first luminescent material 210 and a second luminescent material 220 configured (in parallel tracks) along the length of the belt 535. In further embodiments, the belt arrangement 520 may comprise additional parallel tracks comprising more than two luminescent materials 200.

[0111] Embodiment I in Fig. 2a (right) shows a cross-sectional view of the belt arrangement 530. The light generating device 100 may in embodiments be controlled to generate device light 101 directed to one or more of the (parallel tracks of the) luminescent materials 200. Especially, the light generating system 1000 may comprise an optical element 600 further comprising a rotating prism. The rotating prism may be rotated about an axis parallel to the direction of the device light 101 (as indicated by the curved arrow about the optical axis of the light generating device 100 indicated above the optical element 600) to direct the device light 101 to either the first luminescent material 210 or the second luminescent material 220. In embodiments, an additional actuator 550 may be used to facilitate the rotation of the rotating prism. Hence, in this way, the device light 101 may provide (time averaged) system light 1001 comprising a combination of the first luminescent material light 211 and the second luminescent material light 221. Furthermore, the light generating system 1000 may in embodiments be configured to sequentially irradiate the first luminescent material 210 and the second luminescent material 220 with the device light 101 with a frequency of 50 Hz or larger. Note that, the rotating prism may direct device light 101 to either the first luminescent material 210 or the second luminescent material 220. Note that the illumination area IA may extend over both the first luminescent material 210 and the second luminescent material 220. Furthermore, as already mentioned, the luminescent material surface area LMSA is the sum of the total area of the first luminescent material 210 and the second luminescent material 220 configured on the external surface. Would there be device light 101 illuminating the external surface and the internal surface of the belt element, then the luminescent material surface area LMSA would be double the aforementioned luminescent material surface area LMSA.

[0112] Note that the figure schematically depicts an embodiment of the invention. In embodiments, the one or more tracks may comprise optical elements such as reflectors and diffusers. In an operational mode, the light generating system 1000 may be configured to provide device light 101 by reflecting the generated device light 101 via the reflective track configured on the belt element 520. Similarly, the parallel tracks may especially also comprise a diffuser, wherein the light generating system 1000 may be configured to outcouple scattered or diffused light.

[0113] Embodiment II in Fig. 2a shows an alternative configuration of the belt arrangement 530. In depicted embodiment II, the actuator 540 may displace the belt 535 in a direction perpendicular to the length of the belt 535. Hence, in embodiments, the luminescent material 200 upon which the device light 101 is incident on may be controlled. That is, the belt 535 may be (easily) moved so that the device light 101 may be focused onto a desired track for controlling the color and / or color temperature of the system light 1001. Hence, this may provide the benefit of controlling the (time averaged) composition of system light 1001 comprising the first luminescent material light 211 and the second luminescent material light 221. Hence, in specific embodiments one or more of the following applies: (a) a position of beam of device light 101 is controllable, and (b) a position of the belt arrangement 530 is at least locally controllable.

[0114] Fig. 2b depicts alternative configurations of the belt arrangement 530 in embodiments I and II. An interesting set of alternative embodiments is to have, apart from the first luminescent material 210, a second material having different luminescent properties than the first material, e.g. non-luminescent (such as a diffuser) material, a luminescent material with the same luminescent spectrum but with a different fraction of reflected device light 101 (such as the same luminescent material 200 but with a different concentration or layer thickness, or mixed with a scattering material), or a luminescent material 200 with a different luminescent spectrum. Two such embodiments are described here below.

[0115] In embodiment I, a part of the belt arrangement 530 spanning the (entire) width of the belt 535 may comprise a first luminescent material 210 and another part of the belt 535 (also spanning the width of the belt 535) may comprise the second luminescent material 220. The belt arrangement 530 may in embodiments comprise alternating sections of the first luminescent material 210 and the second luminescent material 220. Alternatively, in embodiment II, the belt arrangement 530 comprises belt element 520 with different sections comprising either the luminescent material 200 or the reflective part 560.

[0116] It will be apparent to the skilled person that a plurality of such different combinations may be conceived in further embodiments. For instance, in embodiments, the belt arrangement 530 may comprise a plurality of luminescent materials 200 in combination with one or more reflective parts 560. Additionally or alternatively, in embodiments, the belt arrangement 530 may also comprise diffusive elements or specular reflective elements in combination with one or more of luminescent materials 200 and the reflective parts 560.

[0117] Note also that in the embodiments depicted the luminescent surface area LMSA refers to the total sum of the area of each region of the segments where the luminescent material 200 is configured.

[0118] In embodiments, the luminescent material 200 may be configured on the belt element 520 in a plurality of different configurations. Fig. 2c depicts one or more such configurations of the belt arrangement 530. Especially, Fig. 2c depicts cross-sectional views of the belt arrangement 530 illustrating the configuration of the luminescent material 200 in relation to the belt 535.

[0119] In embodiment I, the belt arrangement 530 comprises a silicone belt, and wherein the luminescent material 200 is dispersed in (i.e., within) the silicone belt. Especially, the luminescent material 200 may comprise inorganic (phosphor) particles in a matrix material such as a silicone. In this embodiment, the luminescent material 200 may be (entirely) contained within the belt 535.

[0120] In embodiment II, the belt arrangement 530 comprises the luminescent material 200 coated (continuously) over a part of the external surface 532 of the belt arrangement 530. Especially, the belt arrangement 530 may comprise one or more metal parts, and the luminescent material 200 may be configured on at least one of the one or more metal parts. In further embodiments, the metal parts may comprise a highly thermally conductive material (for example copper foil) to facilitate cooling of the belt arrangement 530 (and hence the light generating system 1000). Note that, in some embodiments, the luminescent material 200 may protrude from the surface of the belt 535. Further, in embodiments, the luminescent material 200 in such embodiments may be transmissive for device light 101, and hence, the device light 101 may be reflected by the one or more rotators 510 (and / or reflective guiding elements 507) and undergo subsequent conversion to luminescent material light 201. Note also that, in embodiments, the width of the luminescent material 200 may not span the width Wi of the belt 535.

[0121] In embodiment III, the belt arrangement 530 comprises the luminescent material 200 provided on the external surface of the belt arrangement 530 in parallel tracks along the length of the belt 535. Furthermore, in such embodiments, the belt element 520 may comprise a reflective material such that unconverted device light 101 may undergo subsequent conversion to luminescent material light 201 upon reflection. Furthermore, in such embodiments, the one or more parallel tracks may comprise unique or different luminescent material 200. Hence, in such embodiments, the composition of the system light 1001 may be controlled, thus providing control of CCT, CRI, spectral power distribution, etc.

[0122] In embodiment IV, the belt 535 may further comprise grooves within which the luminescent material 200 may be configured. In some embodiments, such as the embodiment depicted in Fig. 1c, the external surface 532 of the belt element 520 may be in contact with the rotator 510. In such embodiments, the grooves may accommodate the luminescent material 200 such that the luminescent material 200 does not protrude from the surface of the belt 535. Hence, in this way, damage to the luminescent material 200 due to the rotators 510 may be limited (or avoided). This may not be necessary in all embodiments, however, this may be beneficial in embodiments wherein the thickness of the luminescent material 200 is relatively high.

[0123] Fig. 3 shows an embodiment illustrating the color tunability of the light generating system 1000. In embodiments, the composition of the system light 1001 provided by the light generating system 1000 may be controlled. Especially, the spectral power distribution of the system light 1001 may be controlled.

[0124] In embodiments, the light generating system 1000 may comprise the optical element 600 further comprising one or more dichroic filters 580. In the embodiment depicted, the light generating system 1000 comprises a first dichroic filter 581 configured transmissive for device light 101 and reflective for luminescent material light 201. Additionally, in the embodiment depicted, the light generating system 1000 comprises a second dichroic filter 582 configured reflective for device light 101 and transmissive for luminescent material light 201. The second dichroic filter 582 may especially be configured downstream of the first dichroic filter 581. 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”.

[0125] The device light 101 from a first light generating device 110 may be incident on the belt element 520 via the first dichroic filter 581 and the converted luminescent material light 201 may be reflected by the first dichroic filter 581 in a downstream direction towards the second dichroic filter 582. The reflected luminescent material light 201 may pass in a downstream direction (via the second dichroic filter 582) towards an end window. Further, the device light 101 from a second light generating device 120 incident on the second dichroic filter 582 may be reflected in a downstream direction towards the end window 1010. Hence, in this way, the spectral distribution of the system light 1001 may be controlled by controlling the intensity of a device light 111 and a second device light 121 generated by the first light generating device 110 and the second light generating device 120, respectively.

[0126] Furthermore, in embodiments, the light generating system 1000 may comprise the one or more optical elements 600 configured upstream (or downstream) of the end window 1010 to beam shape system light 1001. Especially, the optical element 600 may be selected from the group of a lens, a reflector, a collimator body, etc.

[0127] Fig. 4 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. Fig. 4 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000. Hence, Fig. 4 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, an automotive lighting device 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.

[0128] The term “plurality” refers to two or more.

[0129] 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%.

[0130] The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

[0131] 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”.

[0132] 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.

[0133] 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.

[0134] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0135] 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”.

[0136] The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0137] 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) may provide a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein.

[0138] The invention also may provide 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 may provide 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.

[0139] 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.

[0140] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) comprising a light generating device (100) and a phosphor belt system (500), wherein: the light generating device (100) comprises a solid state light source (10), wherein the solid state light source (10) is selected from the group of laser diodes and superluminescent diodes; wherein the light generating device (100) is configured to generate device light (101); the phosphor belt system (500) comprises (i) n rotators (510), wherein n>2, (ii) a belt element (520), and (iii) an actuator (540); wherein the actuator (540) is configured to rotate the belt element (520) about the rotators (510), wherein each rotator (510) comprises a rotation surface (511); the belt element (520) comprises (a) a belt arrangement (530) comprising an internal surface (531), and (b) a luminescent material (200) having a luminescent material surface area (LMSA); wherein at least two of the rotators (510) are partly in contact with the internal surface (531) of the belt arrangement (530); and wherein the luminescent material (200) is configured to convert at least part of the device light (101) received by the luminescent material (200) into luminescent material light (201); the light generating system (1000) is configured to generate in an operational mode of the light generating system (1000) system light (1001) comprising one or more of the device light (101) and the luminescent material light (201); and the light generating system (1000) is configured such that the device light (101) is directed to part of the belt element (520) at a location where the internal surface (531) of the belt arrangement (530) is configured in contact with one of the guiding elements (507), and / or wherein one or more of the guiding elements (507) and the belt arrangement (530) comprise a thermally conductive material.

2. The light generating system (1000) according to claim 1, wherein the luminescent material surface area (LMSA) is at least 2 times a illumination area (IA) of the device light (101) on the luminescent material (200), wherein the illumination area (I A) of the device light (101) on the luminescent material (200) is defined as a total area of theluminescent material surface area (LMSA) irradiated with the device light (101) during a single rotation of the belt element (520) by, during operation, the device light (101) being incident on a spot on the external surface of the belt element wherein the area of the illuminated spot on the external surface is referred to as a spot size (SZ).

3. The light generating system (1000) according to any one of the preceding claims, wherein during operation of the phosphor belt system (500) the internal surface (531) of the belt arrangement (530) is partly configured in contact with one or more guiding elements (507), wherein the guiding elements (507) comprise the rotators (510) and one or more optional stationary guiding elements (508).

4. The light generating system (1000) according to claim 3, wherein one or more of the guiding elements (507) and the belt arrangement (530) comprise a thermally conductive material, and wherein the thermally conductive material comprises a copper foil.

5. The light generating system (1000) according to any one of the preceding claims, further comprising a gas flow based cooling system (570), wherein the light generating system (1000) is configured such that the gas flow based cooling system (570) is configured to cool at least part of the belt element (520) at a location where during operation of the light generating device (100), the belt element (520) receives device light (101).

6. The light generating system (1000) according to any one of the preceding claims 1-5, wherein the belt arrangement (530) comprises one or more metal parts, and wherein the luminescent material (200) is configured on at least one of the one or more metal parts.

7. The light generating system (1000) according to any one of the preceding claims 1-5, wherein the belt arrangement (530) comprises a silicone belt, and wherein the luminescent material (200) is dispersed in the silicone belt.

8. The light generating system (1000) according to any one of the preceding claims, wherein the luminescent material (200) comprises (i) a first luminescent material (210) configured to convert at least part of the device light (101) reaching the first luminescent material (210) into first luminescent material light (211) and (ii) a secondluminescent material (220) configured to convert at least part of the device light (101) reaching the second luminescent material (220) into second luminescent material light (221), wherein the first luminescent material light (211) and the second luminescent material light (221) have different spectral power distributions; wherein the first luminescent material (210) and the second luminescent material (220) are comprised by different parts of the belt arrangement (530).

9. The light generating system (1000) according to claim 8, wherein the light generating system (1000) is configured to sequentially irradiate the first luminescent material (210) and the second luminescent material (220) with the device light (101) with a frequency of 50 Hz or larger.

10. The light generating system (1000) according to claim 8, wherein the belt arrangement (530) has a belt arrangement width (Wi), wherein the first luminescent material (210) and the second luminescent material (220) are configured at different width positions, wherein the light generating system (1000) is configured such that a width position at a location where the device light (101) is received, is controllable.

11. The light generating system (1000) according to any one of the preceding claims, wherein the belt arrangement (530) has a belt arrangement length (Li) selected from the range of 3-300 cm.

12. The light generating system (1000) according to any one of the preceding claims, wherein the luminescent material (200) comprises a luminescent material of the type A3B5O i2:Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc; and wherein the device light (101) comprises blue light; wherein the light generating device (100) comprises a laser diode.

13. The light generating system (1000) according to any one of the preceding claims 8-12, wherein the belt arrangement (530) further comprises a reflective part (560), configured to reflect at least part of the device light (101) received by the reflective part (560), to provide reflected device light (101); wherein the first luminescent material (210) and the second luminescent material (220) are comprised by different parts of the beltarrangement (530); wherein the light generating system (1000) is configured to provide in an operational mode of the light generating system (1000) system light (1001) comprising averaged over time luminescent material light (201) and reflected device light (101).

14. The light generating system (1000) according to any one of the preceding claims, wherein the system light (1001) comprises in an operational mode of the light generating system (1000) white light having a correlated color temperature selected from the range of 1800-20000 K, and a color rendering index of at least 65.

15. 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, an automotive lighting device, and an optical wireless communication device, comprising the light generating system (1000) according to any one of the preceding claims.

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