国民经济行业分类号：
C4350 | C3874 | C4090 | C3879
当前申请(专利权)人：
LUMENCOR, INC.
原始申请(专利权)人：
SIGNIFY HOLDING B.V.
当前申请(专利权)人地址：
14940 NW GREENBRIER PKWY, 97006, BEAVERTON, OREGON
发明人：
ANTONIS, PETRUS HENDRIKUS | HAENEN, LUDOVICUS JOHANNES LAMBERTUS | VANPOUCKE, PETER | MOS, BARRY | HOELEN, CHRISTOPH GERARD AUGUST | BRULS, DOMINIQUE MARIA | KADIJK, SIMON EME | YUN, LI
摘要：
The invention provides a light generating system (1000), comprising a plurality of light sources (10), an elongated luminescent body (100), and a body holder structure (2000), wherein:the plurality of light sources (10) are configured to provide light source light (11), wherein the light sources (10) are solid state light sources, wherein the plurality of light sources (10) are configured in a light source array (15);the elongated luminescent body (100) has a length (L) and a width (W), wherein the elongated luminescent body (100) comprises luminescent material (120) configured to convert at least part of light source light (11) into luminescent material light (8), wherein the elongated luminescent body (100) and the light source array (15) are configured parallel;the body holder structure (2000) comprises an elongated slit (205) for hosting the elongated luminescent body (100), wherein the elongated slit (205) has a cavity wall (1205) defining the elongated slit (205) and a slit opening (1206), wherein the slit opening (1206) has a slit opening width (WS1), wherein the cavity wall (1205) and the elongated luminescent body (100) have first shortest distances (d11) that vary over the cavity wall (1205), wherein at least part of the cavity wall (1205) is reflective for light source light (11);the light sources (10) are configured at second shortest distances (d21) from the elongated luminescent body (100), wherein the second shortest distance (d21) is selected from the range of 40-1000 μm, and wherein one or more of the plurality of light sources (10) are configured to irradiate with the light source light (11) the elongated luminescent body (100) both (i) directly and (ii) indirectly via the cavity wall (1205).
技术问题语段：
These second light rays are lost and may limit the efficiency of such illumination systems.|Typically, 44% of the converted light may be trapped and may leave the bar at its nose, while 56% of the converted light may be lost at the side walls of the bar.
技术功效语段：
[0011]Relative to some prior art systems, an increase in intensity of the output, an improvement of the efficiency, better thermal management, or more reliability of prior art systems is desirable. Furthermore, it may be desirable to create rod holders that may also be generated with other, e.g. easier production methods like extrusion, or cold forging, that allow for the use of better thermally conductive Aluminum grades. Furthermore, the invention allows a simplified design, with few(er) complex features, resulting in less costly parts.
[0185]An essentially single-piece aluminum block (first body holder element) may allow for a relatively very robust assembly with minimal dust ingress and ample means for fixating heavy heat sinks for good thermal dissipation. One or more springs may support the rod on both ends, especially in such a way that no bending moment is exerted onto the rod.
权利要求：
1. A light generating system comprising a plurality of light sources, an elongated luminescent body, and a body holder structure, wherein:
the plurality of light sources are configured to provide light source light, wherein the light sources are solid state light sources, wherein the plurality of light sources are configured in a light source array;
the elongated luminescent body has a length and a width, wherein the elongated luminescent body comprises luminescent material configured to convert at least part of light source light into luminescent material light;
the body holder structure comprises an elongated slit for hosting the elongated luminescent body, wherein the elongated slit has a cavity wall defining the elongated slit and a slit opening, wherein the slit opening has a slit opening width WS1, wherein WS1≥1.05*W, wherein the cavity wall and the elongated luminescent body have first shortest distances that vary over the cavity wall, wherein at least part of the cavity wall is reflective for light source light;
the light sources are configured at second shortest distances d21 from the elongated luminescent body, and wherein one or more of the plurality of light sources are configured to irradiate with the light source light the elongated luminescent body both (i) directly and (ii) indirectly via the cavity wall, characterized in that:
the elongated slit has a second slit width WS2 at a slit end most remote from the slit opening, wherein the slit opening and the slit end are bridged by cavity wall parts, wherein the second slit width at the slit end is smaller than the slit opening width, wherein WS1/WS2 is at least 1.1,
the cavity wall parts comprise first parts that are configured conformal to part of the elongated luminescent body at first shortest distances selected from the range of ≥100 μm, wherein the first parts are configured closer to the slit end than to the slit opening, and
the slit end is in thermal contact with the elongated luminescent body.
2. The light generating system according to claim 1, wherein:
the elongated luminescent body comprises one or more side faces, wherein the elongated luminescent body comprises a radiation input face and a radiation exit window, wherein the radiation input face is configured in a light receiving relationship with the plurality of light sources, wherein the radiation exit window has an angle (a) unequal to 0° and unequal to 180° with the radiation input face, and wherein the one or more of the plurality of light sources are configured to irradiate with the light source light both (i) the radiation input face of the elongated luminescent body directly and (ii) another part of the one or more side faces indirectly via the cavity wall; and wherein the elongated luminescent body and the light source array are configured parallel.
3. The light generating system according to claim 1, wherein the light source array has a light source array axis, wherein the light sources in the light source array have a largest edge-to-edge width perpendicular to the light source array axis, wherein the edge-to-edge width is larger than the width of the elongated luminescent body and equal to or smaller than the slit opening width, and wherein the second shortest distance is selected from the range of 10-500 μm.
4. The light generating system according to claim 3, wherein the cavity wall parts are straight and configured slanted, having a slant angle (β) relative to the elongated luminescent body selected from the range of 15-45°.
5. The light generating system according to claim 4, wherein the slant angle (β) is selected from the range of 20-40°.
6. The light generating system according to claim 3, wherein the cavity wall parts are curved, tapering in a direction from the slit opening to the slit end.
7. The light generating system according to claim 6, wherein the cavity wall parts have the shape of a Bezier curve.
8. The light generating system according to claim 3, wherein the cavity wall parts comprise second parts, configured closer to the slit opening than to the slit end, wherein the second parts taper in a direction from the slit opening (1206) to the first parts.
9. The light generating system according to claim 1, wherein the slit opening width and the width of the elongated luminescent body have a ratio selected from the range of 1.1≤WS1/W≤5.
10. The light generating system according to claim 1, further comprising n force applying elements configured to keep the elongated body in the elongated slit, wherein n is a natural number of at least 1.
11. The light generating system according to claim 10, wherein the n force applying elements comprise n spring elements, and wherein n is selected from the range of 2-4.
12. The light generating system according to claim 1, wherein the body holder structure comprises one or more heat transfer elements for guiding away heat from the elongated luminescent body, and comprising one or more second heat transfer elements for guiding away heat from the plurality of light sources.
13. The light generating system according to claim 1, wherein the elongated slit further comprises a cavity wall that is conformal with the side wall of the luminescent body facing the cavity wall.
14. The light generating system according to claim 13, wherein an outer surface area of the luminescent body in the range of 40-60% is conformal with the cavity walls of the elongated slit.
15. A projection system or a luminaire comprising the system according to claim 1.
技术领域：
The invention relates to a light generating system, such as for use in a projector or for use in stage lighting, or for use for microscopy or endoscopy illumination. The invention also relates to a luminaire or projection system comprising such light generating system.
BACKGROUND OF THE INVENTION
Luminescent rods are known in the art. WO2006/054203, for instance, describes a light emitting device comprising at least one LED which emits light in the wavelength range of >220 nm to <550 nm and at least one conversion structure placed towards the at least one LED without optical contact, which converts at least partly the light from the at least one LED to light in the wavelength range of >300 nm to ≤1000 nm, characterized in that the at least one conversion structure has a refractive index n of >1.5 and <3 and the ratio A:E is >2:1 and <50000:1, where A and E are defined as follows: the at least one conversion structure comprises at least one entrance surface, where light emitted by the at least one LED can enter the conversion structure and at least one exit surface, where light can exit the at least one conversion structure, each of the at least one entrance surfaces having an entrance surface area, the entrance surface area(s) being numbered A1 . . . An and each of the at least one exit surface(s) having an exit surface area, the exit surface area(s) being numbered E1 . . . En and the sum of each of the at least one entrance surface(s) area(s) A being A=A1+A2 . . . +An and the sum of each of the at least one exit surface(s) area(s) E being E=E1+E2 . . . +En.
EP3330605A1 discloses a fluorescence concentrator system that provides for high brightness light source. The system includes a host doped with fluorescent material, which is optically pumped by an adjacent row of LEDs. A reflective structure surrounds the fluorescence concentrator. The fluorescence concentrator captures a portion of the isotropically emitted fluorescent light and guides it to an output surface. The fluorescent energy emerging the output surface provides a high brightness light source suitable for a number of applications.
发明内容：
[0005]High brightness light sources are interesting for various applications including spots, stage-lighting, headlamps and digital light projection, and (fluorescence) microscopy and endoscopy etc. For this purpose, it is possible to make use of so-called light concentrators where shorter wavelength light is converted to longer wavelengths in a highly transparent luminescent material. A rod of such a transparent luminescent material can be illuminated by LEDs to produce longer wavelengths within the rod. Converted light which will stay in the luminescent material, such as a (trivalent cerium) doped garnet, in the waveguide mode and can then be extracted from one of the (smaller) surfaces leading to an intensity gain.
[0006]In embodiments, the light concentrator (or “luminescent concentrator”) may comprise a rectangular bar (rod) of a (transparent) phosphor doped, high refractive index garnet, capable to convert blue light into green or yellow light and to collect this green or yellow light in a small &endue output beam. The rectangular bar may have six surfaces, four large surfaces over the length of the bar forming the four side walls, and two smaller surfaces at the end of the bar, with one of these smaller surfaces forming the “nose” where the desired light is extracted.
[0007]Under e.g. blue light radiation, the blue light excites the phosphor, after the phosphor start to emit green light in all directions, assuming some cerium comprising garnet applications. Since the phosphor is embedded in—in general—a high refractive index bar, a main part of the converted (green) light is trapped into the high refractive index bar and wave guided e.g. via Total Internal Reflection (TIR) to the nose of the bar where the (green) light may leave the bar. The amount of (green) light generated is proportional to the amount of blue light pumped into the bar. The longer the bar, the more blue LEDs can be applied to pump phosphor material in the bar and the number of blue LEDs to increase the brightness of the (green) light leaving at the nose of the bar can be used. The phosphor converted light, however, can be split into two parts.
[0008]A first part consists of first types of light rays that may hit the side walls of the bar under angles larger than the critical angle of reflection. These first light rays may be trapped in the high refractive index bar and will traverse to the nose of the bar where it may leave as desired light of the system. In general, at least part of the luminescent material light may escape from the radiation exit face directly (without total internal reflection). A second part consist of second light rays (“second light rays”) may hit the side walls of the bar at angles smaller than the critical angle of reflection. These second light rays are not trapped in the bar but will leave the bar at its side walls. These second light rays may be bounced back into the garnet, but in such cases these light rays will always enter the garnet under angles smaller than the total angle of reflection, will traverse straight through the garnet and leave the bar at the opposite side wall. Such, these second light rays will in principle never channel to the nose of the bar. These second light rays are lost and may limit the efficiency of such illumination systems. Typically, 44% of the converted light may be trapped and may leave the bar at its nose, while 56% of the converted light may be lost at the side walls of the bar.
[0009]A high lumen density (HLD) system may comprise a ceramic rod, where blue light is converted to create a high intensity source for theatre lighting, beamers etc. For optical efficiency, i.e. LED alignment with rod, thermal performance, i.e. cooling by conductive heat spreading, and mechanical fixation inside (e.g.) a projector module, the rod may be clamped by metal rod holders.
[0010]The rod may be configured in a rod holder (“body holder structure”). A system may e.g. be based on irradiation of the rod with light sources from two sides of the rod. Such rod-holder may e.g. be generated with die-casting.
[0011]Relative to some prior art systems, an increase in intensity of the output, an improvement of the efficiency, better thermal management, or more reliability of prior art systems is desirable. Furthermore, it may be desirable to create rod holders that may also be generated with other, e.g. easier production methods like extrusion, or cold forging, that allow for the use of better thermally conductive Aluminum grades. Furthermore, the invention allows a simplified design, with few(er) complex features, resulting in less costly parts.
[0012]Hence, it is an aspect of the invention to provide an alternative light generating system (or “lighting system”) comprising a luminescent concentrator, which preferably further at least partly obviates one or more of above-described drawbacks and/or which may have a relatively higher efficiency. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
[0013]Amongst others, the invention proposes to configure an elongated luminescent body in a cavity (or recycling cavity). Hence, a solution may be the use of a recycling cavity. In or close to this cavity a relatively large number of e.g. LEDs can be applied, that can deliver a relatively large amount of optical pump power, e.g. in the range of 100-150 W optical blue light. By using the reflective cavity, it may be possible to couple most of this light (>90%) into e.g. 3 sides of the rod (assuming a rod having a rectangular cross-section), thus eliminating at least partly the disadvantage of a purely single sided irradiation concept, that may use e.g. a U-shaped groove. Furthermore, in this concept a larger number of LEDs can be applied, which means that the module can be operated at lower driving currents in order to achieve the desired optical output. This may result in a much higher Wall Plug Efference (WPE) of the LED pump, and may thus result in an improved lm/Watt performance of the HLD module.
[0014]Hence, in an aspect the invention provides a light generating system (“system”), comprising a plurality of light sources, an elongated luminescent body (“elongated body”, “luminescent body”, “light transmissive body”; sometimes also indicated as “rod”), and a body holder structure (“body holder”). Especially, the plurality of light sources are configured to provide light source light. In embodiments, the light sources are solid state light sources. Especially, the plurality of light sources are configured in a light source array. In embodiments, the elongated luminescent body has a length (L) and a width (W). Especially, the elongated luminescent body comprises luminescent material configured to convert at least part of light source light into luminescent material light. In specific embodiments, the elongated luminescent body and the light source array are configured parallel. Further, especially the body holder structure comprises an elongated slit for hosting the elongated luminescent body. In embodiments, the elongated slit has a cavity wall defining the elongated slit and a slit opening, wherein the slit opening has a slit opening width (WS1). In specific embodiments, WS1≥1.02*W, such as especially WS1≥1.05*W, especially wherein WS1≥1.1*W. Further, especially the cavity wall and the elongated luminescent body have first shortest distances (d11) that may vary over the cavity wall. In specific embodiments, at least part of the cavity wall is reflective for light source light. Yet further, especially the light sources are configured at second shortest distances (d21) from the elongated luminescent body. In embodiments, the second shortest distance (d21) may be selected from the range of 40-1000 μm, though shorter or larger distances may also be possible. One or more of the plurality of light sources may be configured to irradiate with the light source light the elongated luminescent body both (i) directly and (ii) indirectly via the cavity wall.
[0015]Hence, especially the invention provides a light generating system, comprising a plurality of light sources, an elongated luminescent body, and a body holder structure, wherein: (a) the plurality of light sources are configured to provide light source light, wherein the light sources are solid state light sources, wherein the plurality of light sources are configured in a light source array; (b) the elongated luminescent body has a length (L) and a width (W), wherein the elongated luminescent body comprises luminescent material configured to convert at least part of light source light into luminescent material light, wherein the elongated luminescent body and the light source array are configured parallel; (c) the body holder structure comprises an elongated slit for hosting the elongated luminescent body, wherein the elongated slit has a cavity wall defining the elongated slit and a slit opening, wherein the slit opening has a slit opening width (WS1), wherein WS1, wherein the cavity wall and the elongated luminescent body have first shortest distances (d11) that vary over the cavity wall, wherein at least part of the cavity wall is reflective for light source light; and wherein one or more of the plurality of light sources are configured to irradiate with the light source light the elongated luminescent body both (i) directly and (ii) indirectly via the cavity wall. Especially, in embodiments (d) the light sources are configured at second shortest distances (d21) from the elongated luminescent body, wherein the second shortest distance (d21) is selected from the range of 40-1000 μm, though smaller or larger may also be possible (see below).
[0016]With such system, the light source light may be coupled better into the luminescent body. Larger and/or more solid state light sources may be applied, allowing to couple more light into the luminescent body. Further light source light may (essentially) not be lost, as via (reflection from the) cavity walls the light source light may also enter the luminescent body. Hence, one or more light sources may directly irradiate the elongated luminescent body but simultaneously also indirectly irradiate the elongated luminescent body via one or more reflections in the cavity. Nevertheless, the light sources are configured relatively close to the elongated luminescent body.
[0017]In embodiments, the elongated luminescent body and the light sources may be configured such, that at least 50% of the light source light (in Watts) may directly be received by the elongated luminescent body. Further, in embodiments the elongated luminescent body and the light sources may be configured such, that, and at least 10%, such as at least 15%, like even at least 20% of the light source light (in Watts) may indirectly be received by the elongated luminescent body. The term “indirect irradiation” and similar terms indicate light source light that only enters the elongated luminescent body (for the first time) after one or more reflections at the cavity wall. In total, at least 80%, such as at least 85%, like at least 90% of the light source light (in Watts) may directly and indirectly be received by the elongated luminescent body.
[0018]In the present invention, in embodiments the elongated slit and the elongated luminescent body may have dimensions such that there may be clearance between one or more of the one or more side faces and the elongated slit. Further, one or more force applying elements, such as one or more spring elements, may be configured to keep the elongated body pushed into the elongated slit. Especially, one or more spring elements exert a force on one or more side faces of the elongated luminescent body. One or more force applying elements, such as one or more spring elements may be added to suspend the rod and to ensure its thermal contact with the block. The herein described design may in embodiments be compatible with many different LED sizes, as the rod may be suspended above the LEDs and not supported on the sides of the rod, leaving more room available for the LEDs. This may allow for LEDs to be used that have almost the same width as the rod, or that are even wider than the rod itself. Furthermore, as in embodiments the inside of the cavity, in which the rod may be clamped, may be reflective, a small mix-box is created, by which light that is emitted from the side plane of the LEDs still has a chance of hitting the rod, after optical recycling. Also, if the rod is thin, or has a (too) low Ce concentration, the reflective cavity can take care of recycling of leaked blue light, thus enabling different rod dimensions and geometries.
[0019]As indicated above, the body holder structure comprises an elongated slit for hosting the elongated luminescent body. Hence, the elongated slit, elongated luminescent body, and light source array are all configured parallel. The elongated slit may have cross-sectional dimensions such that the elongated luminescent body can be hosted over its total height, or can even be configured recessed, or can be configure protruding. The elongated slit may have cross-sectional dimensions that may partly be conformal with the shape of the elongated luminescent body, e.g. for thermal energy transfer. However, the cross-sectional dimensions may also be partly such that a cavity is created at both sides of the elongated luminescent body (over its entire height or over part of its height). In this way, light may enter the elongated luminescent body not only via a face configured closest to the light sources (which face may comprise the radiation entrance window), but also via a face configured further away from the light sources, such as side faces. Hence, in such embodiment in fact at least part of such side faces are also used as (second) radiation entrance windows.
[0020]Hence, in embodiments the elongated slit has a cavity wall defining the elongated slit and a slit opening. In embodiments, the width of the slit opening is larger than the width of the elongated luminescent body Especially, the width of the slit opening is thus (substantially) larger than the width of the elongated luminescent body. In embodiments, the slit opening has a slit opening width (WS1), wherein WS1≥1.05*W, especially wherein WS1≥1.05*W, especially wherein WS1≥1.1*W.
[0021]As indicated above, the cross-sectional dimension may not be fully conformal with the elongated luminescent body, whereby a cavity may be created. Hence, in embodiments the cavity wall and the elongated luminescent body have first shortest distances (d11) that vary over the cavity wall. For instance, one or more of the cavity walls, especially those directed to side faces at an angle, such as perpendicular, to the radiation input face of the elongated luminescent body, may be slanted or may be curved.
[0022]Further, for recycling of light at least part of the cavity wall is reflective for light source light, even more especially essentially the entire cavity wall is reflective for light source light. Hence, in this way light source light that is coupled out from the elongated luminescent bar, like being transmitted, may be reflected back into the elongated luminescent body, and generate luminescent material light. See further also below, wherein it is also indicated the cavity wall may (also) be reflective for the luminescent material light.
[0023]The light sources may be configured relatively close to the elongated luminescent body. In general however, the (average) distance is not below about 1 μm (see also below). In specific embodiments the light sources are configured at second shortest distances (d21) from the elongated luminescent body, wherein the second shortest distance (d21) in embodiments may be selected from the range of up to about 1000 μm, such as selected from the range of 10-1000 μm, like e.g. 40-1000 μm. In specific embodiments, the second shortest distance (d21) is selected from the range of 10-500 μm. This may minimize thermal coupling (between the LED and the elongated luminescent body) and maximize the input via the indirect pathway. With such system, one or more of the plurality of light sources are configured to irradiate with the light source light the elongated luminescent body both (i) directly and (ii) indirectly via the cavity wall. This may increase the output of the lighting system.
[0024]In specific embodiments, also further elucidated below, the elongated luminescent body comprises one or more side faces, wherein the elongated luminescent body comprises a radiation input face and a radiation exit window, wherein the radiation input face is configured in a light receiving relationship with the plurality of light sources, and wherein the one or more of the plurality of light sources are configured to irradiate with the light source light both (i) the radiation input face of the elongated luminescent body directly and (ii) another part of the one or more side faces indirectly via the cavity wall. As indicated above, the another part of the one or more side faces that are indirectly irradiated by the light source light effectively provide a further radiation input face. Here, the term “radiation input face” is especially reserved for the part of the one or more side faces, such as a side face, that is directly irradiated by the light sources. The term “further radiation input face” may be used for those part(s) of the one or more side faces that are indirectly irradiated. In specific embodiments, also further elucidated below, the radiation exit window has an angle (a) unequal to 0° and unequal to 180° with the radiation input face.
[0025]The light sources are especially configured in an array. The array may be regular or may be irregular, or may comprise a regular arrangement of irregularly arranged light sources, or an irregular arrangement of regularly arranged light sources. The light sources may share a single axis of elongation. However, in other embodiments one or more light sources may be off-axis of the axis of elongation.
[0026]With such system, light sources may be used, such as solid state light sources, having light emitting surfaces, like solid state light source dies, that extend beyond the (cross-sectional) width of the elongated luminescent body. This may be the case when the dies are broader than the width of the elongated luminescent body and/or this may be the case when a 2D array is applied. Hence, in embodiments the light source array has a light source array axis (AA), wherein the light sources in the light source array have a largest edge-to-edge width (WL2) perpendicular to the light source array axis (AA), wherein the edge-to-edge width (WL2) is larger than the width (W) of the elongated luminescent body and equal to or smaller than the slit opening width (WS1). When the light sources comprise solid state light sources that are essentially top emitters, especially WL2≥1.1*W. When the light sources comprise solid state light sources that have both side emission and top emission, WL2≥0.85*W. In specific embodiments, the light sources comprise essentially top emitting solid state light sources. In general, WL2≤2*W, such as WL2≤1.8*W, like especially WL2≤1.5*W, such as e.g. WL2≤1.3*W.
[0027]In general, the elongated slid may have cavity walls that are not straight with (also) a straight angle relative to a top or bottom, but may have cavity walls that are curved and/or slanted. In this way, a suitable cavity may be created wherein light source light after a reflection at the cavity wall enters the elongated luminescent body.
[0028]Hence, the elongated slit has a second slit width (WS2) at a slit end most remote from the slit opening, wherein the slit opening and the slit end are bridged by cavity wall parts, wherein the second slit width (WS2) at the slit end is smaller than the slit opening width (WS1). The slit end may be the bottom or top of the slit. Hence, especially the elongated luminescent body may be in thermal contact with the slit end. In embodiments the elongated luminescent body may have physical contact with the slit end. The slit end may be one of the slit side faces (see also below), or a part thereof.
[0029]In embodiments, WS1/WS2 is at least 1.1, such as at least 1.4, like at least 1.5. Especially, 1.1≤WS1/WS2≤5, like 1.3≤WS1/WS2≤5, such as 1.3≤WS1/WS≤3.
[0030]In embodiments, the height defined by the slit opening and the slit end may essentially be the same as the height of the elongated luminescent body. However, in other embodiments the height defined by the slit opening and the slit end may essentially be a bit larger, such as up to about 50%, like up to about 20%, larger than the height of the elongated luminescent body.
[0031]In specific embodiments, the cavity wall parts are straight and configured slanted, having a slant angle (β) relative to the elongated luminescent body selected from the range of 10-50°, like 15-50°, such as 15-45°, especially selected from the range of 20-40°. Relatively good (simulation) results were obtained with a slant angle (β) of about 30°.
[0032]In other embodiments, the cavity wall parts are curved, tapering in a direction from the slit opening to the slit end. For instance, in embodiments the cavity wall parts have the shape of a Bezier curve. The cavity wall part, that may especially be defined by the Bezier curve, may be defined by a first end, closest to the slit opening, and a second end, closest to the slit end. The second end may be relatively close to the elongated luminescent body. For instance, the second end may be in thermal contact, such as physical contact, with the elongated luminescent body. The cavity wall part, that may especially be defined by the Bezier curve, defines a concave cavity wall part. Hence, the cavity may have concave wall parts, like e.g. a bowl. Hence, the Bezier curve is curved. The first end and the second end of the Bezier curve define two corners of a rectangle, which can be divided in two triangles with a straight line between these triangles (or shared by these triangles), which is a diagonal of the rectangle. In one of the triangles, the Bezier curve will be found, as the Bezier curve is curved. The Bezier curve may further be defined by an intermediate point (which is not on the Bezier curve), which is defined within the triangle wherein the Bezier curve is found. The intermediate point may be chosen such, that incoupling is most efficient. Incoupling is not efficient when the intermediate point is not within one of the triangles (and only found in the triangle that allows a concave Bezier curve/concave wall part). The Bezier curve is especially a rational Bezier curve. The Bezier curve may be defined by:
[0033]B(t)=∑ i=0n(ni)ti(1-t)n-iPiwi∑ i=0n(ni)ti(1-t)n-iwi
Po is the first point, P2 is the second point, and P1 is the intermediate point. Especially, w0=w2=1. The value of w1 may be chosen from the range of about 0.4-1.5, especially at least 0.5, such as selected from the range of 0.5-1.2. P1 and w1 may be chosen such that light (source light) incoupling is most efficient (and thus the outcoupling via the radiation exit window is also largest). The value oft varies from 0 at the first point to 1 at the second point. Hence, t is a variable between 0-1 that defines all points on the Bezier curve. Curved shapes other than Bezier curves may also be possible. Further, optionally the cavity walls, or parts thereof, may be facetted, such that effectively a (virtually) curved cavity wall may be obtained. Hence, in embodiments a facetted cavity wall may also essentially follow a Bezier curve (though other curved shapes may also be possible).
[0034]The cavity wall parts comprise first parts that are configured conformal to part of the elongated luminescent body at first shortest distances (d11) selected from the range of ≤100 μm, wherein the first parts are configured closer to the slit end than to the slit opening. Alternatively or additionally, the cavity wall parts may (also) comprise second parts, configured closer to the slit opening than to the slit end, wherein the second parts taper in a direction from the slit opening to the first parts.
[0035]Combinations of such embodiments may also be possible, e.g. a part of a cavity edge that tapers in a flat way and a part of a cavity edge that tapers in a curved way.
[0036]The slit end is in thermal contact with the elongated luminescent body.
[0037]Further, in embodiments the slit opening width (WS1) and the width (W) of the elongated luminescent body have a ratio selected from the range of 1.1≤WS1/W≤5, like 1.3≤WS1/W≤5, such as 1.3≤WS1/W≤3. Too small or too large ratios may lead to light loss.
[0038]In embodiments, a feature in the herein proposed design(s) is (are) the simplicity of the rod holder in combination with one or more (simple) springs, holding the rod in the rod holder cavity. In this way, the rod and rod holder combination may in embodiments form a subassembly. This subassembly can be thermally connected to other parts, e.g. an own heat sink, or can be thermally coupled to another part e.g. the LED board, which than forms the thermal interface. Furthermore, a heat sink structure can be integrated into the rod holder to further increase thermal performance, whilst lowering part-count and thus cost. Furthermore, the rod inside the rod holder may be insulated from external forces, other than those imposed by the springs, which is highly advantageous when external heat sinks are being applied (most likely clamped) onto the complete module. With the present invention, it may also be possible to use cold forging and extrusion to produce e.g. the body holder structure, which may also have the right properties regarding reflectivity and thermal conductivity.
[0039]The plurality of light sources are configured to provide light source light. At least part of the light source light is absorbed by the luminescent body and converted into luminescent material light. To this end, the luminescent body comprises a radiation input face, wherein the radiation input face is configured in a light receiving relationship with the plurality of light sources. Hence, the light sources and the luminescent body are configured such that during operation at least part of the light source light enters the luminescent body (and is converted thereby). Further, as indicated above the elongated luminescent body comprises luminescent material configured to convert at least part of light source light (received at the radiation input face) into luminescent material light. The luminescent material light may escape from the luminescent body. Especially, for instance by using one or more reflectors at one or more sides and/or faces of the luminescent body, the luminescent material light may especially escape from the luminescent body at essentially one face. This face, here below also indicated as second face, may comprise a radiation exit window. In embodiments, the second face is the radiation exit window. Further, the elongated luminescent body comprises one or more side faces. The number of side faces is herein also indicated with reference N. The elongated luminescent body may especially comprise four side faces, providing a rectangular cross-section (perpendicular to an axis of elongated of the elongated body). The elongated luminescent body may in embodiments comprise a garnet type A3B5O12 luminescent material comprising trivalent cerium. In specific embodiments, the length (L) of the elongated body may be selected from the range of 10-200 mm, such as selected from the range of 40-150 mm. Embodiments of the light sources and the elongated body are also further elucidated below.
[0040]The light sources are configured in an array. Such array may have a length in the same range as the length of the elongated body. The array may be a 1D array or a 2D array. In embodiments, the array is a 1D array, or an array of sets of two light sources. In order to maximize output, the light sources may have small distances to each other. Here, especially the inter-light source distance or inter-light source distance between adjacent light source along the length of the array is meant. When the array is a 2D array, the array may be an k1×k2 array, wherein k1>>k2. For instance, k2 may be 2-4, such as 2. The number k1 may e.g. be at least 5, such as at least 10. Especially, the elongated luminescent body and the light source array are configured parallel. The total number of light sources may be indicated as k, and may be at least 5, such as at least 10.
[0041]In embodiments, the plurality of k light sources may essentially be identical light sources. The k light sources may be essentially identical in terms of spectral power distribution and maximum power. The k light sources may further also be essentially identical in terms of dimensions (e.g. of the die). Hence, in embodiments the plurality of light sources may be selected from the same bin. However, in embodiments also different types of light sources may be used.
[0042]The luminescent material is configured to convert at least part of light source light (received at the radiation input face) into luminescent material light. Hence, the light source(s) generate the luminescent material light. In embodiments, the light sources that are used to generate the luminescent material light may be solid state light sources all of the same bin. In embodiments, the light sources that are used to generate the luminescent material light all have essentially the same peak maximum (peak emission wavelength). In embodiments, the light sources that are used to generate the luminescent material light may essentially all have the spectral power distribution and are all configured to generate essentially the same irradiance at the radiation input face.
[0043]Further, the light generating system comprises a body holder structure. The body holder structure comprises an elongated slit for hosting the elongated luminescent body. Hence, the luminescent body fits in the elongated slit. The body holder structure may comprise a body holder structure length. The slit may have a slit length. The slit length and body holder structure length may in embodiments be essentially the same, i.e. the slit is available over the entire length of the body holder structure. In other embodiments, the slit length may be shorter. In general, however, the slit extends to at least one of the edges of the body holder structure. The slit may be open at least one side. In this way, the elongate body can be provided in the slit in a direction perpendicular to an axis of elongated of the elongated body and the elongated slit. The one or more force applying elements, such as one or more spring elements, may keep the elongated luminescent body in the elongated slit. Essentially, in embodiments the slit may have a cross-sectional shape that has the same shape as the luminescent body (see however below for specific embodiments wherein the slit may have a cross-sectional shape that is not the same shape as the luminescent body). For instance, when the luminescent body has a hexagonal cross-sectional shape, the slit will have a shape wherein the hexagonal body fits with slit faces parallel to two or more, such as three, side faces of the luminescent body. Likewise, when for instance the luminescent body has a rectangular cross-section shape, the slit will have a shape wherein the rectangular body fits with slit faces parallel to two or more, such as three, side faces of the luminescent body. Hence, the elongated slit is especially configured for hosting the elongated luminescent body. Especially, however, the elongated slit has dimensions such that it does not provide an interference fit, but allows for some clearance. Hence, especially the width of the elongated slit may be larger than a width of the elongated luminescent body. Therefore, in embodiments the elongated slit and the elongated luminescent body have dimensions such that there is clearance between one or more of the one or more side faces and the elongated slit. In embodiments, the clearance may be in total selected from the range of 1-10 mm, such as selected from the range of 10 μm-2 mm, especially at maximum about 100 μm. Embodiments of the body holder structure, the slit, as well as the configuration of the elongated luminescent body in the slit, are also further elucidated below. As also indicated below, the clearance may vary over the
具体实施方式：
[0192]A light emitting device according to the invention may be used in applications including but not being limited to a lamp, a light module, a luminaire, a spot light, a flash light, a projector, a (digital) projection device, automotive lighting such as e.g. a headlight or a taillight of a motor vehicle, arena lighting, theater lighting and architectural lighting.
[0193]Light sources which are part of the embodiments according to the invention as set forth below, may be adapted for, in operation, emitting light with a first spectral distribution. This light is subsequently coupled into a light guide or waveguide; here the light transmissive body. The light guide or waveguide may convert the light of the first spectral distribution to another spectral distribution and guides the light to an exit surface.
[0194]An embodiment of the light generating system as defined herein is schematically depicted in FIG. 1a. FIG. 1a schematically depicts a light generating system 1000 comprising a plurality of solid state light sources 10 and a luminescent concentrator 5 comprising an elongated light transmissive body 100 having a first face 141 and a second face 142 defining a length L of the elongated light transmissive body 100. The elongated light transmissive body 100 comprising one or more radiation input faces 111, here by way of example two oppositely arranged faces, indicated with references 143 and 144 (which define e.g. the height H), which are herein also indicated as edge faces or edge sides 147. Further the light transmissive body 100 comprises a radiation exit window 112, wherein the second face 142 comprises the radiation exit window 112. The entire second face 142 may be used or configured as radiation exit window. The plurality of solid-state light sources 10 are configured to provide (blue) light source light 11 to the one or more radiation input faces 111. As indicated above, they especially are configured to provide to at least one of the radiation input faces 111 a blue power Wopt of in average at least 0.067 Watt/mm2. Reference BA indicates a body axis, which will in cuboid embodiments be substantially parallel to the edge sides 147. Reference 140 refers to side faces or edge faces in general.
[0195]The elongated light transmissive body 100 may comprise a ceramic material 120 configured to wavelength convert at least part of the (blue) light source light 11 into converter light 101, such as at least one or more of green and red converter light 101. As indicated above the ceramic material 120 comprises an A3B5O12:Ce3+ ceramic material, wherein A comprises e.g. one or more of yttrium (Y), gadolinium (Gd) and lutetium (Lu), and wherein B comprises e.g. aluminum (Al). References 20 and 21 indicate an optical filter and a reflector, respectively. The former may reduce e.g. non-green light when green light is desired or may reduce non-red light when red light is desired. The latter may be used to reflect light back into the light transmissive body or waveguide, thereby improving the efficiency. Note that more reflectors than the schematically depicted reflector may be used. Note that the light transmissive body may also essentially consist of a single crystal, which may in embodiments also be A3B5O12:Ce3+.
[0196]The light sources may in principle be any type of light source, but is in an embodiment a solid state light source such as a Light Emitting Diode (LED), a Laser Diode or Organic Light Emitting Diode (OLED), a plurality of LEDs or Laser Diodes or OLEDs or an array of LEDs or Laser Diodes or OLEDs, or a combination of any of these. The LED may in principle be an LED of any color, or a combination of these, but is in an embodiment a blue light source producing light source light in the UV and/or blue color-range which is defined as a wavelength range of between 380 nm and 490 nm. In another embodiment, the light source is an UV or violet light source, i.e. emitting in a wavelength range of below 420 nm. In case of a plurality or an array of LEDs or Laser Diodes or OLEDs, the LEDs or Laser Diodes or OLEDs may in principle be LEDs or Laser Diodes or OLEDs of two or more different colors, such as, but not limited to, UV, blue, green, yellow or red.
[0197]The light sources 10 are configured to provide light source light 11, which is used as pump radiation 7. The luminescent material 120 converts the light source light into luminescent material light 8 (see also FIG. 1e). Light escaping at the light exit window is indicated as converter light 101, and will include luminescent material light 8. Note that due to reabsorption part of the luminescent material light 8 within the luminescent concentrator 5 may be reabsorbed. Hence, the spectral distribution may be redshifted relative e.g. a low doped system and/or a powder of the same material. The light generating system 1000 may be used as luminescent concentrator to pump another luminescent concentrator.
[0198]FIGS. 1a-1b schematically depict similar embodiments of the light generating system. Further, the light generating system may include further optical elements, either separate from the waveguide and/or integrated in the waveguide, like e.g. a light concentrating element, such as a compound parabolic light concentrating element (CPC). The light generating systems 1 in FIG. 1b further comprise a collimator 24, such as a CPC.
[0199]As shown in FIGS. 1a-1b and other Figures, the light guide has at least two ends, and extends in an axial direction between a first base surface (also indicated as first face 141) at one of the ends of the light guide and a second base surface (also indicated as second face 142) at another end of the light guide.
[0200]The collimator 24 may be supported by an optics interface plate (not shown).
[0201]FIG. 1a also schematically depicts an embodiment wherein the radiation exit window 112 has an angle (α) unequal to 0° and unequal to 180° with one or more of the one or more side faces 140. Further, the radiation input face 111 and the radiation exit window 112 may have an angle α unequal to 0° and unequal to 180° with one or more of the one or more side faces 140. Here, angle α is 90°.
[0202]Reference 15 indicates an array of light sources 10. In FIG. 1a, and some of the further figures, the n force applying elements are not yet schematically drawn (see further e.g. FIGS. 3a-3c).
[0203]Reference 15 indicates an array (of light sources 10).
[0204]FIG. 1c schematically depicts some embodiments of possible ceramic bodies or crystals as waveguides or luminescent concentrators. The faces are indicated with references 141-146. The first variant, a plate-like or beam-like light transmissive body has the faces 141-146. Light sources, which are not shown, may be arranged at one or more of the faces 143-146 (general indication of the edge faces is reference 147). The second variant is a tubular rod, with first and second faces 141 and 142, and a circumferential face 143. Light sources, not shown, may be arranged at one or more positions around the light transmissive body. Such light transmissive body will have a (substantially) circular or round cross-section. The third variant is substantially a combination of the two former variants, with two curved and two flat side faces. In the embodiment having a circular cross-section the number of side faces may be considered unlimited (co).
[0205]In the context of the present application, a lateral surface of the light guide should be understood as the outer surface or face of the light guide along the extension thereof. For example in case the light guide would be in form of a cylinder, with the first base surface at one of the ends of the light guide being constituted by the bottom surface of the cylinder and the second base surface at the other end of the light guide being constituted by the top surface of the cylinder, the lateral surface is the side surface of the cylinder. Herein, a lateral surface is also indicated with the term edge faces or side 140.
[0206]The variants shown in FIG. 1c are not limitative. More shapes are possible; i.e. for instance referred to WO2006/054203, which is incorporated herein by reference. The ceramic bodies or crystals, which are used as light guides, generally may be rod shaped or bar shaped light guides comprising a height H, a width W, and a length L extending in mutually perpendicular directions and are in embodiments transparent, or transparent and luminescent. The light is guided generally in the length L direction. The height H is in embodiments <10 mm, in other embodiments <5 mm, in yet other embodiments <2 mm. The width W is in embodiments <10 mm, in other embodiments <5 mm, in yet embodiments <2 mm. The length L is in embodiments larger than the width W and the height H, in other embodiments at least 2 times the width W or 2 times the height H, in yet other embodiments at least 3 times the width W or 3 times the height H. Hence, the aspect ratio (of length/width) is especially larger than 1, such as equal to or larger than 2, such as at least 5, like even more especially in the range of 10-300, such as 10-100, like 10-60, like 10-20. Unless indicated otherwise, the term “aspect ratio” refers to the ratio length/width. FIG. 1c schematically depicts an embodiment with four long side faces, of which e.g. two or four may be irradiated with light source light.
[0207]The aspect ratio of the height H:width W is typically 1:1 (for e.g. general light source applications) or 1:2, 1:3 or 1:4 (for e.g. special light source applications such as headlamps) or 4:3, 16:10, 16:9 or 256:135 (for e.g. display applications). The light guides generally comprise a light input surface and a light exit surface which are not arranged in parallel planes, and in embodiments the light input surface is perpendicular to the light exit surface. In order to achieve a high brightness, concentrated, light output, the area of light exit surface may be smaller than the area of the light input surface. The light exit surface can have any shape, but is in an embodiment shaped as a square, rectangle, round, oval, triangle, pentagon, or hexagon.
[0208]Note that in all embodiments schematically depicted herein, the radiation exit window is especially configured perpendicular to the radiation input face(s). Hence, in embodiments the radiation exit window and radiation input face(s) are configured perpendicular. In yet other embodiments, the radiation exit window may be configured relative to one or more radiation input faces with an angle smaller or larger than 90°.
[0209]Note that, in particular for embodiments using a laser light source to provide light source light, the radiation exit window might be configured opposite to the radiation input face(s), while the mirror 21 may consist of a mirror having a hole to allow the laser light to pass the mirror while converted light has a high probability to reflect at mirror 21. Alternatively or additionally, a mirror may comprise a dichroic mirror.
[0210]FIG. 1d very schematically depicts a projector or projector device 2 comprising the light generating system 1000 as defined herein. By way of example, here the projector 2 comprises at least two light generating systems 1000, wherein a first light generating system 1000a is configured to provide e.g. green light 101 and wherein a second light generating system 1000b is configured to provide e.g. red light 101. Light source 10 is e.g. configured to provide blue light. These light sources may be used to provide the projection (light) 3. Note that the additional light source 10, configured to provide light source light 11, is not necessarily the same light source as used for pumping the luminescent concentrator(s). Further, here the term “light source” may also refer to a plurality of different light sources. The projector device 2 is an example of a light generating system 1000, which light generating system is especially configured to provide light generating system light 1001, which will especially include light generating system light 101.
[0211]High brightness light sources are interesting for various applications including spots, stage-lighting, headlamps and digital light projection.
[0212]For this purpose, it is possible to make use of so-called luminescent concentrators where shorter wavelength light is converted to longer wavelengths in a highly transparent luminescent material. A rod of such a transparent luminescent material can be used and then it is illuminated by LEDs to produce longer wavelengths within the rod. Converted light which will stay in the luminescent material such as a doped garnet in the waveguide mode and can then be extracted from one of the surfaces leading to an intensity gain (FIG. 1e).
[0213]High-brightness LED-based light source for beamer applications appear to be of relevance. For instance, the high brightness may be achieved by pumping a luminescent concentrator rod by a discrete set of external blue LEDs, whereupon the phosphor that is contained in the luminescent rod subsequently converts the blue photons into green or red photons. Due to the high refractive index of the luminescent rod host material (typically 1.8) the converted green or red photons are almost completely trapped inside the rod due to total internal reflection. At the exit facet of the rod the photons are extracted from the rod by means of some extraction optics, e.g. a compound parabolic concentrator (CPC), or a micro-refractive structure (micro-spheres or pyramidal structures). As a result, the high luminescent power that is generated inside the rod can be extracted at a relatively small exit facet, giving rise to a high source brightness, enabling (1) smaller optical projection architectures and (2) lower cost of the various components because these can be made smaller (in particular the, relatively expensive, projection display panel).
[0214]FIG. 1f schematically depicts an embodiment of a luminaire 1 (or other type of lighting device) comprising the light generating system 1000. The luminaire 1 provide light which may—in a control mode of the luminaire—comprise the lighting system light 1001.
[0215]FIGS. 2a-2b schematically depict embodiments of a light generating system 1000 comprising a light source 10 configured to provide light source light 11 and an elongated luminescent body 100 having a length L (see FIG. 2b).
[0216]As indicated above, the elongated luminescent body 100 comprises (n) side faces 140, here 4, over at least part of the length. The (n) side faces 140 comprise a first side face 143, comprising a radiation input face 111, and a second side face 144 configured parallel to the first side face 143, wherein the side faces 143, 144 define a height h.
[0217]As indicated above, the elongated luminescent body 100 further comprises a radiation exit window bridging at least part of the height h between the first side face 143 and the second side face 144 (see especially FIG. 1a). The luminescent body 100 comprises a garnet type A3B5O12 luminescent material 120 comprising trivalent cerium, wherein the garnet type A3B5O12 luminescent material 120 is configured to convert at least part of the light source light 11 into converter light 101.
[0218]Further, the light generating system 1000 comprises one or more heat transfer elements 200 in thermal contact with one or more side faces 140 and a reflector 2100 configured at the second side face 144 and configured to reflect light source light 11 escaping from the elongated luminescent body 100 via second face 144 back into the elongated luminescent body 100.
[0219]The one or more heat transfer elements 200 are especially configured parallel to at least part of one or more of the side faces 140 over at least part of the length of the elongated luminescent body 100 at a shortest distance (d11) from the respective one or more side faces 140. The shortest distance d11 is especially 1 μm≤d11≤100 μm.
[0220]As shown in FIGS. 2a-2b, the one or more heat transfer elements 200 comprise one or more heat transfer element faces 201 directed to one or more side faces 140. As shown in these schematic drawings, the one or more heat transfer elements 200 are at least in thermal contact with all side faces 140 other than the first side face 143. Further, as also shown in these schematic drawings, the one or more heat transfer elements 200 may be configured as a monolithic heat transfer element 220. In embodiments, this monolithic heat transfer element 220 is configured in thermal contact with a support 240 for the light source 10. The one or more heat transfer elements 200 may especially be configured for guiding away heat from the luminescent body 100.
[0221]A heat transfer element face 201 of the one or more heat transfer element 200 directed to the second face 144 comprises the reflector 2100. Here, all faces 201 directed to the luminescent body 100 comprise such reflector 2100.
[0222]FIG. 2b schematically depict another embodiment of the monolithic heat transfer element 220, including a slit 205 configured to host the luminescent body 100. The light sources 10 may be provided as LED bar. The monolithic heat transfer element 220 is used for cooling of the luminescent body 100.
[0223]The optional intermediate plate, indicated with reference 250, may serve as a spacer to keep the luminescent body at the desired distance from the light sources and may also serve as a reflector for the light that escapes from the luminescent body side faces. As an alternative, the spacer could be integrated with the one or more heat transfer element 200, especially a top one or more heat transfer element 200 (such as a top cooling block).
[0224]In FIGS. 2a-2b, the one or more heat transfer elements are configured within a circle section of at least 180°, here in fact about 270°.
[0225]As shown above, the light generating system 1000 comprises in embodiments a plurality of light sources 10 configured to provide light source light 11 and an elongated luminescent body 100 comprising one or more side faces 140, the elongated luminescent body 100 comprising a radiation input face 111 and a radiation exit window 112, wherein the radiation input face 111 is configured in a light receiving relationship with the plurality of light sources 10, wherein the elongated luminescent body 100 comprises luminescent material 120 configured to convert at least part of light source light 11 (received at the radiation input face 111) into luminescent material light 8.
[0226]FIG. 3a schematically depict an embodiment of a body holder structure 2000. The body holder structure 2000 comprises an elongated slit 205 for hosting the elongated luminescent body 100. As shown, the elongated slit 205 and the elongated luminescent body 100 have dimensions such that there is clearance between one or more of the one or more side faces 140 and the elongated slit 205.
[0227]Further, the light generating system may comprise one or more spring elements 300 configured to keep the elongated body 100 pushed into the elongated slit 205. Schematically, embodiments of two spring elements 300 are schematically depicted in FIG. 3a. Note that the contact area between the spring elements 300 and the elongated body 100 is only a fraction of the relevant side face, here indicated as side face 143. As shown in FIG. 3a and some other drawings, there may be at least two spatially different contact points of the one or more spring elements 300 with elongated luminescent body 100.
[0228]Hence, as shown the elongated luminescent body 100 comprises a plurality of N side faces 140, and wherein the elongated slit 205 comprises N−1 slit side faces 2140, wherein one or more of the side faces 140 are in thermal contact with one or more of the slit side faces 2140. The slit 205 may also comprise less than N−1 side faces, but especially at least two.
[0229]Reference 1300 indicates a force applying element, such as the spring element. Reference 303 indicates a clamping position or contact point (contact area), i.e. where the force applying element clamps the body 100 to the rod holder 2000.
[0230]FIG. 3b schematically depicts an embodiment wherein a single spring wire 300 is applied, attached to a support 1100, which may be a support for the plurality of light sources (see also below). FIG. 3c schematically depicts in more detail such single spring wire 300. FIG. 3d schematically depicts an embodiment of the system 1000 in some more detail. The elongated luminescent body 100 comprises a first face 141 and a second face 142 defining a length L of the elongated luminescent body 100, wherein the second face 142 comprises the radiation exit window 112. The first side face 143 has first area A2. The one or more spring elements 300 are in physical contact with a contact area Ac of the first side face 143, wherein the contact area Ac is at maximum 20% of the first area A2, here, much smaller, such as at maximum a few percent. The collimator 24 may be supported by an optics interface plate (not shown).
[0231]As shown in the embodiments of FIGS. 3a-3d, the one or more spring elements 300 are configured in contact with the first side face 143 at 1-4 positions distributed over the length L of the elongated luminescent body 100.
[0232]FIG. 3e schematically depicts in some more detail an embodiment wherein a side face 140 is in thermal contact with a slit side face 2140. Thermal contact without essential optical contact may be achieved by distance holders or by having only a limited area in physical contact with the slit side face 2140 (or only a limited area of the slid side face 2140 having physical contact with the side face 140. Hence, even though being in physical contact, a first average distance d11 may be larger than zero. In embodiments, the first average distance d11 may be at least 1 μm from the slid side face 2140. In the embodiment of FIG. 3e, two of the side faces 140 are in thermal contact with two of the slit side faces 2140.
[0233]FIG. 3d also schematically depicts an embodiment comprising one or more second heat transfer elements 1200 for guiding away heat from the plurality of light sources 10. The light sources 10 may be configured on a support 1100. The heat transfer elements 1200 may be in thermal contact with the support, or may form a single body and be a support for the light sources 10.
[0234]As schematically shown in FIG. 3e, the one or more of the slit side faces 2140 being in thermal contact with one or more of the side faces 140 comprises one or more reflectors 2100 being reflective for at least part of the light source light 11 (and for at least part of the luminescent material light). Especially, at least a slit side face 2140 configured opposite of the light sources 10, with the elongated luminescent body 100 configured between that slit side face 2140 and the light sources 10, comprises a reflector 2100.
[0235]In embodiments, the surface of 2000 may exhibit reflecting properties by nature e.g. reflective aluminum. Hence, in this way the slit side face 2140 may comprise a reflector 2100. FIGS. 3d and 3e also show an embodiment wherein the elongated luminescent body 100 comprises a first side face 143 and a second side face 144 defining a height H, wherein the one or more spring elements 300 are in thermal contact with part of the first side face 143, wherein the first side face 143 comprises the radiation input face 111, and wherein the second side face 144 is in thermal contact with one of the slit side faces 2140. FIG. 3e, and some other Figures, show embodiments wherein the plurality of N side faces 140 are configured perpendicular to the first face 141, and wherein the light sources 10 are configured to irradiate at least part of a single side face 140 only. As shown in e.g. FIG. 3e, the body holder structure 2000 comprises one or more heat transfer elements 200. This may be body as well as the heat fins. They may in embodiments be a single body. Hence, in embodiments the body holder structure 2000 is a monolithic body. However, in other embodiments the body holder structure may comprise a plurality of elements which may be assembled and which may thereby form the slit 205.
[0236]In embodiments, the invention may make use of a reflective cavity that enables efficient coupling of pump light via three sides of the rod. This may enable use of multiple rows of LEDs on a support and/or may also enables the use of bigger LEDs and/or even LEDs that have besides top emitting a (significant) part of side emission.
[0237]An embodiment (including some variants) of the invention is schematically illustrated in FIG. 4a. For instance, light generated by the LEDs will be coupled into the rod directly (as normally the HLD modules) but also via the reflective cavity. This may result in an increase of the efficiency of coupling light into the rod. This example cavity as used in calculations. Angle rod reflective wall is 30°. The reflective cavity enables multiple rows of LEDs (FIG. 4b), use of very large LEDs much wider than the rod with (FIGS. 4a, 3c, 4d, 4e, 4j, 4k, 4l, 4m). In the table below results of a ray-set model calculations are provided. For a rod cross section of 1.2×1.56 mm, a LED-rod distance of 150 μm, a reflective cavity as illustrated in FIG. 4a with angle of reflective wall of 30°. Different reflectivity's of the reflective wall were used. With a small LED, for instance the 1×1 mm CSP top emitting LED, the coupling efficiencies is 96% without a cavity. With the described cavity and a reflectivity of 90% the gain in coupling is 1.4%. More beneficial may become the cavity with 2 rows of these LEDs with a distance between the row of 200 μm. Without cavity in coupling efficiency is 69% with the cavity and 90% reflectivity (specular) the coupling efficiency becomes 93%. Example 3 is a LED with dimensions 1.41×1.41 mm and significant side emission, such as e.g. at least 10%. The coupling efficiency without cavity is 87% and this value increases with a cavity up to 93%. With a 4 mm2 2×2 mm LED the coupling efficiency without cavity is 77%. With cavity this becomes 93%. With bigger LEDs and/or multiple row with bigger LEDs the effect of the cavity may become even more important.
[0238]Absolute coupling performance into 1.2 × 1.56 mm rod;distance LED - rod 150 μm with single LED in centerNocavityCavityCavityAbsolute coupling 150 μmcavityR 85%R 90%R 95%1 mm2 1 × 1 CSP96%97%97%97%2 × 1 mm2 1 × 1 CSP 200 μm d69%91%93%94%LL FC 2 mm2 1.41 × 1.4187%93%93%94%4 mm2 (sim 4 × 1 mm2 csp)77%92%93%94%Padbar 2 mm2 (cross)92%96%96%97%
[0239]Amongst others FIG. 4a and other figures, schematically depict an embodiment wherein the radiation input face is configured in a light receiving relationship with the plurality of light sources. The one or more of the plurality of light sources are configured to irradiate with the light source light both (i) the radiation input face of the elongated luminescent body directly and (ii) another part of the one or more side faces indirectly via the cavity wall. These part(s) of the one or more side faces that are indirectly irradiated by the light source light effectively provide a further radiation input face. For instance, at least 25%, such as at least 50% of the total number of light sources, or even all, may be configured to irradiate with the light source light both (i) the radiation input face of the elongated luminescent body directly and (ii) another part of the one or more side faces indirectly via the cavity wall.
[0240]FIG. 4b schematically depicts essentially the same embodiment as schematically depicted in FIG. 4a, but now with a 2D array with two rows of light sources 10. FIG. 4c schematically depicts essentially the same embodiment as schematically depicted in FIG. 4a but here with a curved reflective cavity. Here, the reflective cavity is on the top side close to the support with an additional feature. FIG. 4d schematically depicts essentially the same embodiment as schematically depicted in FIG. 4a but here with the reflective cavity not starting at the bottom of the rod. FIG. 4e schematically depicts essentially the same embodiment as schematically depicted in FIG. 4a but here with a very big reflective cavity.
[0241]FIGS. 4a-4m schematically depict embodiments and variants of a light generating system 1000, comprising a plurality of light sources 10, an elongated luminescent body 100, and a body holder structure 2000.
[0242]The plurality of light sources 10 are configured to provide light source light 11, wherein the light sources 10 are solid state light sources. The plurality of light sources 10 are configured in a light source array 15. Here, embodiments are schematically depicted of the single-sided lighting concept.
[0243]The elongated luminescent body 100 has a length L (see e.g. FIGS. 1 and 1c, etc.) and a width W. The elongated luminescent body 100 comprises luminescent material 120 configured to convert at least part of light source light 11 into luminescent material light. As shown in these cross-sectional vies, the elongated luminescent body 100 and the light source array 15 are configured parallel.
[0244]The body holder structure 2000 comprises an elongated slit 205 for hosting the elongated luminescent body 100. The elongated slit 205 has a cavity wall 1205 defining the elongated slit 205 and a slit opening 1206. The slit opening 1206 has a slit opening width WS1, wherein e.g. WS1≥1.1*W. The slit opening width WS1 and the width W of the elongated luminescent body 100 may in specific embodiments have a ratio selected from the range of 1.1≤WS1/W≤5, like in embodiments 1.3≤WS1/W≤5.
[0245]The cavity wall 1205 and the elongated luminescent body 100 have first shortest distances d11 that vary over the cavity wall 1205. As schematically depicted, (at least part of) the cavity wall 1205 is reflective for light source light 11.
[0246]The light sources 10 are configured at second shortest distances d21 from the elongated luminescent body 100. Especially, the second shortest distance d21 is selected from the range of 40-1000 μm. Especially, the second shortest distance d21 may be selected from the range of 10-500 μm. One or more of the plurality of light sources 10 are configured to irradiate with the light source light 11 the elongated luminescent body 100 both directly and indirectly via the cavity wall 1205.
[0247]The clearance, in fact d11 between the cavity wall 1205 at a side face of the elongated luminescent body, may vary over the height of the elongated luminescent body, due to the tapering.
[0248]Reference SA indicates the slit axis. Reference AA indicates the light source array axis. Reference A indicates the axis of elongation of the elongated body. The slit axis and the axis of elongation may be configured parallel. The slit axis, the light source array axis, and the axis of elongation may be all configured parallel.
[0249]The light source array 15 has a light source array axis AA. Further, the light sources 10 in the light source array 15 have a largest edge-to-edge width WL2 perpendicular to the light source array axis AA. As schematically indicated, the edge-to-edge width WL2 is larger than the width W of the elongated luminescent body 100 and equal to or smaller than the slit opening width WS1. In general, WL2≤2*W, such as WL2≤1.8*W, like especially WL2≤1.5*W, such as e.g. WL2≤1.3*W.
[0250]When the light sources comprise solid state light sources that are essentially top emitters, especially WL2≥1.1*W. When the light sources comprise solid state light sources that have both side emission and top emission, in embodiments WL2≥0.85*W. In specific embodiments, the light sources comprise essentially top emitting solid state light sources.
[0251]As schematically depicted, the elongated slit 205 has a second slit width WS2 at a slit end 1207 most remote from the slit opening 1206. The slit opening 1206 and the slit end 1207 are bridged by cavity wall parts 2131,2132. The second slit width WS2 at the slit end 1207 is smaller than the slit opening width WS1.
[0252]In embodiments, the slit end 1207 is in thermal contact with the elongated luminescent body 100.
[0253]As schematically depicted in FIGS. 4a, 4b, (4d), 4e, 4j and 4l the cavity wall parts 2131,2132 are straight and configured slanted, having a slant angle β relative to the elongated luminescent body 100. This angle β may especially be selected from the range of 10-50°, such as 15-45° (see FIG. 4a, like selected from the range of 20-40°.
[0254]Referring to FIG. 4a, and assuming an angle β of about 30°, at least 50% of