WO2018141625A1 - Module concentrateur de lumière - Google Patents

Module concentrateur de lumière Download PDF

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Publication number
WO2018141625A1
WO2018141625A1 PCT/EP2018/051844 EP2018051844W WO2018141625A1 WO 2018141625 A1 WO2018141625 A1 WO 2018141625A1 EP 2018051844 W EP2018051844 W EP 2018051844W WO 2018141625 A1 WO2018141625 A1 WO 2018141625A1
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WO
WIPO (PCT)
Prior art keywords
light
light transmissive
transmissive body
elongated
radiation
Prior art date
Application number
PCT/EP2018/051844
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English (en)
Inventor
Adrianus Johannes Stephanus Maria De Vaan
Original Assignee
Philips Lighting Holding B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Philips Lighting Holding B.V. filed Critical Philips Lighting Holding B.V.
Publication of WO2018141625A1 publication Critical patent/WO2018141625A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0003—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being doped with fluorescent agents
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0075—Arrangements of multiple light guides
    • G02B6/0076—Stacked arrangements of multiple light guides of the same or different cross-sectional area
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
    • G02B19/0047—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source
    • G02B19/0061—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a LED
    • G02B19/0066—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a LED in the form of an LED array

Definitions

  • the invention relates to a lighting device, such as for use in a projector or for use in stage lighting.
  • Luminescent rods are known in the art.
  • WO2006/054203 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 Ai ...
  • WO2014/198619 describes a light emitting device comprising a light source adapted for, in operation, emitting light with a first spectral distribution, a first light guide comprising a first light input surface and a first light exit surface arranged opposite to one another, and further comprising an end surface extending perpendicular with respect to the first light input surface, and a second light guide comprising a second light input surface and a second light exit surface extending perpendicular with respect to one another.
  • the first light guide is adapted for receiving the light with the first spectral distribution from the light source at the first light input surface, guiding the light with the first spectral distribution to the first light exit surface and to the end surface and coupling a part of the light with the first spectral distribution out of the first light exit surface into the second light guide and coupling another part of the light with the first spectral distribution out of the end surface.
  • the second light guide is adapted for receiving light with the first spectral distribution coupled out of the first light guide at the second light input surface, guiding the light to the second light exit surface, converting at least a part of the light with the first spectral distribution to light with a second spectral distribution and coupling the light with the second spectral distribution out of the second light exit surface.
  • WO2016/075014 describes a lighting device comprising a plurality of solid state light sources and an elongated ceramic body having a first face and a second face defining a length (L) of the elongated ceramic body, the elongated ceramic body comprising one or more radiation input faces and a radiation exit window, wherein the second face comprises said radiation exit window, wherein the plurality of solid state light sources are configured to provide blue light source light to the one or more radiation input faces and are configured to provide to at least one of the radiation input faces a photon flux of at least 1.0* 10 17 photons/(s.mm 2 ), wherein the elongated ceramic body comprises a ceramic material configured to wavelength convert at least part of the blue light source light into at least converter light, wherein the ceramic material comprises an A3B 5 0i2:Ce 3+ ceramic material, wherein A comprises one or more of yttrium (Y), gadolinium (Gd) and lutetium (Lu), and wherein B comprises aluminum (Al).
  • US20060227570 describes illumination system, such as might be used for illuminating a projection system, includes at least a first source of incoherent light capable of generating light in a first wavelength range.
  • the system also includes a body containing a fluorescent material that emits light in a second wavelength range, different from the first wavelength range, when illuminated by light in the first wavelength range.
  • the body has an extraction area and at least some of the light at the second wavelength is internally reflected within the body to the extraction area.
  • High brightness light sources are interesting for various applications including spots, stage-lighting, headlamps and digital light projection, etc.
  • 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.
  • the light concentrator may comprise a rectangular bar (rod) of a phosphor doped, high refractive index garnet, capable to convert blue light into green light and to collect this green light in a small etendue 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.
  • 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 a high refractive index bar, a main part of the converted (green) light is trapped into the high refractive index bar and wave guided 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 LED's can be applied to pump phosphor material in the bar and the number of blue LED's 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.
  • a first part consist of first types of light rays that will hit the side walls of the bar under angles larger than the critical angle of reflection. These first light rays are 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.
  • a second part consist of second light rays (“second light rays”) that will hit the side walls of the bar at angles smaller than the total 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 never channel to the nose of the bar. These second light rays are lost and will limit the efficiency of such illumination systems. Typically, in current systems, 44% of the converted light is trapped and will leave the bar at its nose, while 56% of the converted light is lost at the side walls of the bar.
  • an aspect of the invention to provide an alternative lighting device 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.
  • the invention provides a lighting device (“device”) comprising one or more light sources, especially a plurality of light sources, a luminescent concentrator
  • the luminescent concentrator comprises a first elongated light transmissive body ("body” or “elongated body” or “light transmissive body” or “luminescent body”).
  • the first elongated light transmissive body may be bar shaped, having a first face and a second face defining a length (L) of the light transmissive body, the light transmissive body comprises one or more radiation input faces ("input face” or “light incoupling face”) and a radiation exit window ("exit window”), wherein the second face (or “nose") comprises the first radiation exit window; the first elongated light transmissive body comprises a luminescent material (may also be indicated as "phosphor") configured to convert at least part of light source light received at one or more radiation input faces into luminescent material light, and the luminescent concentrator is configured to couple at least part of the luminescent material light out at the first radiation exit window as converter light, wherein the first radation exit window has a first radiation exit window surface area (Al).
  • a luminescent material may also be indicated as "phosphor”
  • the luminescent concentrator is configured to couple at least part of the luminescent material light out at the first radiation exit window as converter light
  • the beam shaping optical element is optically coupled with the first radiation exit window.
  • the beam shaping optical element comprises a radiation entrance window configured to receive at least part of the converter light, wherein the radiation entrance window has a radiation entrance window surface area (A2) which is larger than the first radiation exit window surface area (Al).
  • A2 radiation entrance window surface area
  • Al first radiation exit window surface area
  • luminescent element may herein be used.
  • converter light may be coupled out from the converter via the beam shaping optical element.
  • part of the light that is lost such as (second light rays) via side faces, may still be received at the beam shaping optical element, either directly, or via reflection, or via refraction, or via another waveguide (especially not comprising luminescent material), and also be comprised in the lighting device light that escapes from the beam shaping optical element.
  • the luminescent concentrator may be smaller and thus less expensive, whereas essentially the same beam may be produced.
  • the lighting device may comprise one or more of (i) a second elongated light transmissive body, configured parallel to the first elongated light transmissive body, and (ii) a first reflective surface configured parallel to one or more side faces of the first elongated light transmissive body and the optional second elongated light transmissive body.
  • part of the light that might be lost such as (second light rays) via side faces, may be guided to the beam shaping optical element, either directly, or via reflection, or via refraction, or via the other waveguide (especially not comprising
  • a smaller luminescent concentrator (with thus a smaller radiation exit window) may be applied. This may save costs and may make the efficiency and reliability of the lighting device higher.
  • the larger the luminescent converter the more risk there may be in production process errors. Further, the larger the luminescent converter, the higher the risk on breakage.
  • the luminescent concentrator may comprise a higher luminescent material concentration than in case a larger luminescent converter would be used, such that according the Beer-Lambert law a similar amount of light conversion will occur, as it may be desireable to have essentially the same output (from the nose).
  • the lighting devices may comprise a plurality of light sources to provide light source light that is at least partly converted by the light transmissive body, more especially the luminescent material of the light transmissive body, into converter light.
  • the converted light can at least partially escape form the first radiation exit window, which is in optical contact with the beam shaping optical element, more especially the radiation entrance window thereof.
  • the beam shaping optical element may especially comprises a collimator.
  • the collimator may be used to convert (to "collimate") the light beam into a beam having a desired angular distribution.
  • the beam shaping optical element especially comprises a light transmissive body comprising the radiation entrance window.
  • the beam shaping optical element may be a body of light transmissive material that is configured to collimate the converter light from the luminescent body.
  • the beam shaping optical element comprises a compound parabolic like collimator, such as a CPC (compound parabolic concentrator).
  • the beam shaping optical element may have cross section (perpendicular to an optical axis) with a shape that is the same as the cross-section of the luminescent body (perpendicular to the longest body axis (which body axis is especially parellel to a radiation input face). For instance, would the latter have a rectangular cross section, the former may also have such rectangular cross section, though the dimension may be different. Further, the dimension of the beam shaping optical element may vary over its length (as it may have a beam shaping function).
  • first radiation exit window is in optical contact with the radiation entrance window thereof.
  • optical contact and similar terms, such as “optically coupled” especially mean that the light escaping the first radiation exit window surface area (Al) may enter the beam shaping optical element radiation entrance window with minimal losses (such as fresnel reflection losses or TIR (total internal reflection) losses) due to refractive index differences of these elements.
  • the losses may be minimized by one or more of the following elements: (1) a direct optical contact between the two optical elements, (2) providing an optical glue between the two optical elements, preferably the optically glue having a refractive index higher that the lowest refractive index of the two individual optical elements, (3) providing the two optical elements in close vicinity (e.g.
  • the optically transparent interface material between the two optical elements, preferably the optically transparent interface material having a refractive index higher that the lowest refractive index of the two individual optical elements, the optically transparent interface material might be a liquid or a gel or (5) providing optical Anti Reflective coatings on the surfaces of the two individual optical elements.
  • the term “radationally coupled” especially means that the luminescent body (i.e. the first elongated light transmissive body) and the beam shaping optical element are associated with each other so that at least part of the radiation emitted by the luminescent body is received by the luminescent material.
  • the luminescent body and the beam shaping optical element, especially the indicated “windows” may in embodiments be in physical contact with each other or may in other embodiments in separated from each other with a (thin) layer of optical glue, e.g. having a thickness of less than about 1 mm, preferably less than 100 ⁇ .
  • the light sources are radationally coupled with the luminescent body, though in general the light sources are not in physical contact with the luminescent body (see also below).
  • the luminescent body is a body and as in general also the beam shaping optical element is a body, the term “window” herein may especially refer to side or a part of a side.
  • the first radation exit window of the luminescent body has a first radiation exit window surface area (Al) and the radiation entrance window of the beam shaping optical element has a radiation entrance window surface area (A2) which is larger than the first radiation exit window surface area (Al). Especially, 0.05 ⁇ A1/A2 ⁇ 0.8. Hence, a part of the radiation entrance window of the beam shaping optical element is thus not in (optical) contact with the luminescent body. However, radiation that escapes from the luminescent body, especially from one or more side faces may reach the entrance window of the beam shaping optical element.
  • the luminescent body comprises one or more side faces, wherein the beam shaping optical element is configured to receive at the radiation entrance window at least part of the converter light that escapes from the one or more side faces.
  • the lighting device may further comprise a first reflective surface, especially configured parallel to one or more side faces, and configured at a first distance (dl) from the luminescent body, wherein the first reflective surface is configured to reflect at least part of the converter light that escapes from the one or more side faces back into the luminescent body or to the beam shaping optical element.
  • the space between the reflective surface and the one or more side faces comprises a gas, wherein the gas comprises air.
  • the first distance may e.g. be in the range of 0.1 ⁇ - 20 mm, such as in the range of 1 ⁇ - 10 mm, like 2 ⁇ - 10 mm.
  • the first distance as indicated above may be an average distance (with the values as indicated above, such as at least 0.1 ⁇ , like at least 1 ⁇ , such as e.g. up to 20 mm) but at a few places, for instance for configuration purposes, there may be physical contact. For instance, there may be contact with the edge faces over less than 10%, such as over less than 5%> of the total area of the side faces.
  • the minimum average distance may be as defined e.g.
  • this physical contact may be with at maximum 10% of the surface area of the surface with which the element (mirror and/or heat sink) is in physical contact, such as at maximum 5%, like at maximum 2%, even more especially at maximum 1%.
  • an average distance may e.g. be between ca 2 and 10 um (the lower limit basically determined as being a few times the wavelength of interest; here, assuming e.g. visible light). This may be achieved by having physical contact (to secure that distance) over less than 1% of the total area of that respective side face.
  • a heat sink or a reflector, or the relevant surface may have some protrusions, like a surface roughness, by which there may be contact between the surface and the element, but in average the distance is at least ⁇ ; (i.e. the wavelength of interest) (in order to essentially prevent optical contact), but there is physical contact with equal to or less than 10% of the surface of the body (to which the element may be thermally coupled and/or optically not coupled), especially substantially less.
  • the distance is at least wavelength of interest, more especially at least twice the wavelength of interest. Further, as there may be some contact, e.g.
  • an average distance is at least ⁇ ;, such as at least 1.5* ⁇ ;, like at least 2* ⁇ ;, such as especially about 5* ⁇ ;, wherein ⁇ ; is the wavelength of interest.
  • the wavelength of interest may especially be the wavelength at maximum emission of the luminescence of the luminescent material. Such average distance may also be indicated as "air gap”.
  • the lighting device comprises a second elongated light transmissive body ("second body” or “second elongated body” or “second light transmissive body”; or “second luminescent body” would the second body also comprise a luminescent material), especially configured parallel to the luminescent body, the second elongated light transmissive body having a first face and a second face defining a second length (L2) of the second elongated light transmissive body, the second elongated light transmissive body comprising one or more radiation input faces for receiving at least part of the converter light that escapes from one or more side faces of the luminescent body, and a radiation exit window, wherein the second face of the second elongated light transmissive body comprises the radiation exit window, wherein the second radation exit window has a second radiation
  • the second elongated light transmissive body may (also) especially be bar shaped.
  • the body not configured to convert light source light and/or converter light may in embodiments comprise no luminescent material.
  • the absorption of light source light of the material of the second body may be at least 10 times lower than of the first body, such as at least 100 times lower.
  • the second elongated light transmissive body may essentially have the same length as the luminescent body.
  • L1/L2 may be in the range of 0.9-1.1, such as 0.5-1.05, like about 1.
  • one or more other dimension may also essentially be the same.
  • a length and width of the radiation input faces for receiving at least part of the converter light that escapes from one or more side faces may essentially be the same as the length and width of one of those one or more side faces.
  • the length and width of a radation input face of the second light transmissive body are essentially identical to the length and with of a side face of the luminescent body for optimal optical coupling.
  • the luminescent body and the second elongated light transmissive body may especially be in the range of 0.1 to 1000 ⁇ . In between, there may be an gap, filled with a gas, such as air.
  • the radiation exit window area of the luminescent body and the radation exit window area of the second elongated light transmissive body may be in the order of the area of the entrance window. Especially, at least 50% of the area of the entrance window is optically coupled with the exit window of the luminescent body and second elongated light transmissive body. Hence, in specific embodiments 0.5 ⁇ (A1+A11)/A2 ⁇ 1.1. As will be elucidated below, there may also be a plurality of first elongated light transmissive bodies and/or a plurality of second elongated light transmissive bodies.
  • Al is the accumulated area of the surface areas of the radiation exit window surface areas of the individual first elongated light transmissive bodies
  • Al 1 is the accumulated area of the surface areas of the second radiation exit window surface areas of the second elongated light transmissive bodies, respectively.
  • the luminescent body has a first index of refraction (nl)
  • the second elongated light transmissive body has a second index of refraction (n2)
  • the optical element comprises a light transmissive body having a third index of refraction (n3).
  • the indices of refraction refer to those indices at the same wave strengthsh, such as at, by way of example, 550 nm.
  • the index of refraction of two or more of the luminescent bodies, the second elongated light transmissive body, and the light transmissive body of the beam shaping optical element are matched to each other.
  • the refractive indices of the latter two are specially close to or smaller than the refractive index of the luminescent body.
  • the differences are equal to or smaller than about
  • the index of refraction of the luminescent body may be larger than the index of refraction of the second elongated light transmissive body.
  • the index of refraction of the luminescent body may be larger than of the beam shaping optical element.
  • the index of refraction of the second elongated light transmissive body may be essentially the same as of the beam shaping optical element (i.e. in embodiments 0.95 ⁇ n2/n3 ⁇ 1.05).
  • the luminescent body comprises a ceramic body or single crystal (see further also below), and one or more of the second elongated light transmissive body and the beam shaping optical element comprises a glass or a polymeric material.
  • the second elongated light transmissive body may also be of essentially identical material as the luminescent body, but without the luminescent material.
  • the beam shaping optical element and the second elongated light transmissive body are a single body of the same material.
  • a single piece of glass or a single piece of polymeric material may be configured as second elongated light transmissive body and beam shaping optical element.
  • At one or more sides of the second elongated light transmissive body one or more first elongated light transmissive bodies may be configured.
  • the second elongated light transmissive body may have a transmission of at least 99 %/cm for converter light. Alternatively or additionally the second elongated light transmissive body may also have a transmission of at least 95 %/cm for the light source light. Likewise, the beam shaping optical element may have a transmission of at least 99 %/cm for converter light. Alternatively or additionally the the beam shaping optical element may also have a transmission of at least 99 %/cm for the light source light.
  • the element "/cm" refers to the transmission per cm path length through the material. Note that the term
  • second may optionally also refer to a plurality of second elongated light transmissive bodies.
  • the embodiments wherein a second elongated light transmissive body is applied may further include one or more reflectors for reflecting back light that may escape from the luminescent body or from the second elongated light transmissive body.
  • the lighting device may further comprise a first reflective surface configured parallel to one or more side faces and configured at a first distance (dl) from the luminescent body, wherein the first reflective surface is configured to reflect at least part of the converter light that escapes from the one or more side faces of the luminescent body or from the second light transmissive body back into the luminescent body or to the beam shaping optical element or into the second elongated light transmissive body.
  • the first reflective surface may be configured at a second distance (d2) from the second elongated light transmissive body.
  • the second distance may e.g. be in the range of 0.1 ⁇ -20 mm, such as in the range of 0.5 ⁇ -10 mm, like 1 ⁇ -5 mm.
  • the second elongated light transmissive body is (thus) configured between the first elongated light transmissive bod in the first reflective surface.
  • the lighting device is especially designed to have as much radiation coupled out from the first radiation exit window, or more especially the beam shaping optical element.
  • the invention provides the different areas of the first radiation exit window and the radiation entrance window, the optional second elongated light transmissive body, and the optional reflective surface.
  • the light receiving face of the second elongated light transmissive body may comprise facets that promote the propagation of converter light in a direction of the second radiation exit window (or in a direction of the radiation entrance window).
  • the facets may be configured such, that due to refraction, the optical axis of the incoming radation is directed to the second radiation exit window (or to the radiation entrance window).
  • the lighting device has a side face of the luminescent body configured parallel to a radiation input face of the second elongated light transmissive body.
  • One or more of (i) the side face and the radiation input face, especially the radiation input face of the second elongated light transmissive body, comprise facets for directing converter light propagating from the first light transmissive body via the second elongated light transmissive body in a direction of the beam shaping optical element.
  • the lighting device may comprise a plurality of luminescent bodies (first elongated light transmissive bodies), optionally in combination with one or more second elongated light transmissive bodies.
  • the lighting device comprises a plurality of first elongated light transmissive bodies, configured parallel to each other, each of the first elongated light transmissive bodies configured to receive at least part of the light source light of the plurality of light sources, wherein further in specific embodiments wherein the lighting device also comprises the second elongated light transmissive bodysecond elongated light transmissive element, the one or more radiation input faces of the second elongated light transmissive body are configured for receiving at least part of the converter light that escapes from one or more side faces of the plurality of first elongated light transmissive bodies, wherein the first radiation exit window surface area (Al) is the accumulated first radiation exit window surface areas of each of the first elongated light transmissive bodies of the plurality of first elongated light transmiss
  • the lighting device may be configured to provide blue, green, yellow, orange, or red light, etc. Further, in specific embodiment, the lighting device may be configured to provide white light. If desired, monochromaticity may be improved using optical filter(s).
  • the term "light concentrator” or “luminescent concentrator” is herein used, as one or more light sources irradiate a relative large surface (area) of the light converter, and a lot of converter light may escape from a relatively small area (exit window) of the light converter. Thereby, the specific configuration of the light converter provides its light concentrator properties. Especially, the light concentrator may provide Stokes-shifted light, which is Stokes shifted relative to the pump radiation.
  • the term “luminescent concentrator” or “luminescent element” may refer to the same element, especially an elongated light transmissive body (comprising a luminescent material), wherein the term
  • concentration and similar terms may refer to the use in combination with one or more light sources and the term “element” may be used in combination with one or more, including a plurality, of light sources.
  • light source may e.g. be a laser, especially a solid state laser (like a LED laser).
  • the first elongated light transmissive body comprises a luminescent material and can herein especially be used as luminescent concentrator.
  • the first elongated light transmissive body is herein also indicated as
  • a plurality of light sources may be applied.
  • 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(s)), 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”.
  • the light concentrator comprises a light transmissive body.
  • the light concentrator is especially described in relation to an elongated light transmissive body, such as a ceramic rod or a crystal, such as a single crystal. However, these aspects may also be relevant for other shaped ceramic bodies or single crystals.
  • the light transmissive body has light guiding or wave guiding properties. Hence, the light transmissive body is herein also indicated as waveguide or light guide. As the light transmissive body is used as light concentrator, the light transmissive body is herein also indicated as light concentrator.
  • the light transmissive body will in general have (some) transmission of visible light in a direction perpendicular to the length of the light transmissive body. Without the activator (dopant) such as trivalent cerium, the transmission in the visible might be close to 100%.
  • the term "visible light” especially relates to light having a wavelength selected from the range of 380-780 nm.
  • the transmission can be determined by providing light at a specific wavelength with a first intensity to the light transmissive body under perpendicular radiation and relating the intensity of the light at that wavelength measured after transmission through the material, to the first intensity of the light provided at that specific wavelength to the material (see also E-208 and E-406 of the CRC Handbook of Chemistry and Physics, 69th edition, 1088-1989).
  • the light transmissive body may have any shape, such as beam like or rod like, however especially beam like (cuboid like). However, the light transmissive body may also be disk like, etc.
  • the invention is not limited to specific embodiments of shapes, neither is the invention limited to embodiments with a single exit window or outcoupling face.
  • the transmissive body have a circular cross-section, then the width and height may be equal (and may be defined as diameter). Especially, however, the light transmissive body has a cuboid like shape, such as a bar like shape, and is further configured to provide a single exit window.
  • the light transmissive body may especially have an aspect ratio larger than 1, i.e. the length is larger than the width.
  • the light transmissive body is a rod, or bar (beam), or a rectangular plate, though the light transmissive body does not necessarily have a square, rectangular or round cross-section.
  • the light source is configured to irradiate one of the longer faces (side edge), herein indicated as radiation input face, and radiation escapes from a face at a front (front edge), herein indicated as radiation exit window.
  • the solid state light source, or other light source is not in physical contact with the light transmissive body. Physical contact may lead to undesired outcoupling and thus a reduction in concentrator efficiency.
  • the light transmissive body comprises two substantially parallel faces, the radiation input face and opposite thereof the opposite face. These two faces define herein the width of the light transmissive body. In general, the length of these faces defines the length of the light transmissive body.
  • the light transmissive body may have any shape, and may also include combinations of shapes.
  • the radiation input face has an radiation input face area (A), wherein the radiation exit window has a radiation exit window area (E), and wherein the radiation input face area (A) is at least 1.5 times, even more especially at least two times larger than the radiation exit window area (E), especially at least 5 times larger, such as in the range of 2-50,000, especially 5-5,000 times larger.
  • the elongated light transmissive body comprises a geometrical concentration factor, defined as the ratio of the area of the radiation input faces and the area of the radiation exit window, of at least 1.5, such as at least 2, like at least 5, or much larger (see above).
  • a geometrical concentration factor defined as the ratio of the area of the radiation input faces and the area of the radiation exit window, of at least 1.5, such as at least 2, like at least 5, or much larger (see above).
  • This allows e.g. the use of a plurality of solid state light sources (see also below).
  • a small but high intense emissive surface is desired. This cannot be obtained with a single LED, but can be obtained with the present lighting device.
  • the radiation exit window has a radiation exit window area (E) selected from the range of 1- 100 mm 2 .
  • the emissive surface can be small, whereas nevertheless high intensity may be achieved.
  • the light transmissive body in general has an aspect ratio (of length/width). This allows a small radiation exit surface, but a large radiation input surface, e.g. irradiated with a plurality of solid state light sources.
  • the light transmissive body has a width (W) selected from the range of 0.5-100 mm.
  • the light transmissive body is thus especially an integral body, having the herein indicated faces.
  • the generally rod shaped or bar shaped light transmissive body can have any cross sectional shape, but in embodiments has a cross section the shape of a square, rectangle, round, oval, triangle, pentagon, or hexagon.
  • the ceramic or crystal bodies are cuboid.
  • the body may be provided with a different shape than a cuboid, with the light input surface having somewhat the shape of a trapezoid. By doing so, the light flux may be even enhanced, which may be advantageous for some applications.
  • width may also refer to diameter, such as in the case of a light transmissive body having a round cross section.
  • the elongated light transmissive body further has a width (W) and a height (H), with especially L>W and L>H.
  • the first face and the second face define the length, i.e. the distance between these faces is the length of the elongated light transmissive body.
  • These faces may especially be arranged parallel.
  • the length (L) is at least 2 cm, such as 4-20 cm.
  • the light transmissive body has a width (W) selected to absorb more than 95% of the light source light.
  • the light transmissive body has a width (W) selected from the range of 0.03-4 cm, especially 0.05-2 cm, such as 0.1-1.5 cm, like 0.1-1 cm. With the herein indicated cerium concentration, such width is enough to absorb substantially all light generated by the light sources.
  • the light transmissive body may also be a cylindrically shaped rod.
  • the cylindrically shaped rod has one flattened surface along the longitudinal direction of the rod and at which the light sources may be positioned for efficient incoupling of light emitted by the light sources into the light transmissive body.
  • the flattened surface may also be used for placing heatsinks.
  • the cylindrical light transmissive body may also have two flattened surfaces, for example located opposite to each other or positioned perpendicular to each other.
  • the flattened surface extends along a part of the longitudinal direction of the cylindrical rod. Especially however, the edges are planar and configured perpendicular to each other.
  • the light transmissive body may also be a fiber or a multitude of fibers, for instance a fiber bundle, either closely spaced or optically connected in a transparent material.
  • the fiber may be referred to as a luminescent fiber.
  • the individual fiber may be very thin in diameter, for instance, 0.1 to 0.5 mm.
  • the light transmissive body may also comprise a tube or a plurality of tubes.
  • the tube (or tubes) may be filled with a gas, like air or another gas having higher heat conductivity, such as helium or hydrogen, or a gas comprising two or more of helium, hydrogen, nitrogen, oxygen and carbon dioxide.
  • the tube (or tubes) may be filled with a liquid, such as water or (another) cooling liquid.
  • the light transmissive body as set forth below in embodiments according to the invention may also be folded, bended and/or shaped in the length direction such that the light transmissive body is not a straight, linear bar or rod, but may comprise, for example, a rounded corner in the form of a 90 or 180 degrees bend, a U-shape, a circular or elliptical shape, a loop or a 3-dimensional spiral shape having multiple loops.
  • This provides for a compact light transmissive body of which the total length, along which generally the light is guided, is relatively large, leading to a relatively high lumen output, but can at the same time be arranged into a relatively small space.
  • luminescent parts of the light transmissive body may be rigid while transparent parts of the light transmissive body are flexible to provide for the shaping of the light transmissive body along its length direction.
  • the light sources may be placed anywhere along the length of the folded, bended and/or shaped light transmissive body. Parts of the light transmissive body that are not used as light incoupling area or light exit window may be provided with a reflector.
  • the lighting device further comprises a reflector configured to refiect luminescent material light back into the light transmissive body. Therefore, the lighting device may further include one or more reflectors, especially configured to reflect radiation back into the light transmissive body that escapes from one or more other faces than the radiation exit window.
  • a face opposite of the radiation exit window may include such reflector, though in an embodiment not in physical contact therewith.
  • the reflectors may especially not be in physical contact with the light transmissive body.
  • the lighting device further comprises an optical reflector (at least) configured downstream of the first face and configured to refiect light back into the elongated light transmissive body.
  • optical reflectors may also be arranged at other faces and/or parts of faces that are not used to couple light source light in or luminescence light out. Especially, such optical reflectors may not be in physical contact with the light transmissive body.
  • optical reflector(s) may be configured to refiect one or more of the luminescence and light source light back into the light transmissive body.
  • substantially all light source light may be reserved for conversion by the luminescent material (i.e. the activator element(s) such as especially Ce 3+ ) and a substantial part of the luminescence may be reserved for
  • reflector may also refer to a plurality of reflectors.
  • the one or more reflectors may consist of a metal reflector, such as a thin metal plate or a reflective metal layer deposited on a substrate, such a se.g. glass.
  • the one or more reflectors may consist of an optical transparent body containing optical structure to refiect (part) of the light such as prismatic structures.
  • the one or more reflectors may consist of specular reflectors.
  • the one or more reflectors may contain microstructures, such as prism structures or sawtooth structures, designed to reflect the lightrays towards a desired direction.
  • such reflectors are also present in the plane where the lightsources are positioned, such that that plane consist of a mirror having openings, each opening having the same size as a corresponding lightsource allowing the light of that corresponding lightsource to pass the mirror layer and enter the elongated (first) light transmissive body while light that traverses from the (first) light transmissive body in the direction of that plane receives a high probability to hit the mirror layer and will be reflected by that mirror layer back towards the (first) light transmissive body.
  • the terms “coupling in” and similar terms and “coupling out” and similar terms indicate that light changes from medium (external from the light transmissive body into the light transmissive body, and vice versa, respectively).
  • the light exit window will be a face (or a part of a face), configured (substantially) perpendicular to one or more other faces of the waveguide.
  • the light transmissive body will include one or more body axes (such as a length axis, a width axis or a height axis), with the exit window being configured (substantially) perpendicular to such axis.
  • the light input face(s) will be configured (substantially) perpendicular to the light exit window.
  • the radiation exit window is especially configured perpendicular to the one or more radiation input faces. Therefore, especially the face comprising the light exit window does not comprise a light input face.
  • the lighting device may have a mirror configured at the first face configured to reflect light back into the elongated light transmissive body, and/or may have one or more of an optical filter, a (wavelength selective) mirror, a reflective polarizer, light extraction structures, and a collimator configured at the second face.
  • the mirror may e.g. be a wavelength selective mirror or a mirror including a hole. In the latter embodiment, light may be reflected back into the body but part of the light may escape via the hole.
  • the optical element may be configured at a distance of about 0.01-1 mm, such as 0.1-1 mm from the body.
  • an optical filter Downstream of the radiation exit window, optionally an optical filter may be arranged. Such optical filter may be used to remove undesired radiation. For instance, when the lighting device should provide red light, all light other than red may be removed.
  • the lighting device further comprises an optical filter configured downstream of the radiation exit window and configured to reduce the relative contribution of undesired light in the converter light (downstream of the radiation exit window).
  • an interference filter may be applied for filtering out light source light.
  • the lighting device further comprises a collimator configured downstream of the radiation exit window (of the highest order luminescent concentrator) and configured to collimate the converter light.
  • a collimator like e.g. a CPC (compound parabolic concentrator), may be used to collimate the light escaping from the radiation exit window and to provide a collimated beam of light.
  • the lighting device may comprise a plurality of light sources. These plurality of light sources may be configured to provide light source light to a single side or face or to a plurality of faces; see further also below. When providing light to a plurality of faces, in general each face will receive light of a plurality of light sources (a subset of the plurality of light sources).
  • a plurality of light sources will be configured to provide light source light to a radiation input face. Also this plurality of light sources will in general be configured in a row.
  • the light transmissive body is elongated, the plurality of light sources may be configured in a row, which may be substantially parallel to the axis of elongated of the light transmissive body.
  • the row of light sources may have substantially the same length as the elongated light transmissive body.
  • the light transmissive body has a length (L) in the range of about 80-120% of the second length (L2) of the row of light sources; or the row of light sources has a length in the range of about 80-120% of the length of the light transmissive body.
  • the light sources are light sources that during operation emit (light source light) at least light at a wavelength selected from the range of 200-490 nm, especially light sources that during operation emit at least light at wavelength selected from the range of 400-490 nm, even more especially in the range of 440-490 nm.
  • This light may partially be used by the luminescent material.
  • the light source is configured to generate blue light.
  • the light source comprises a solid state light source (such as a LED or laser diode).
  • the term "light source” may also relate to a plurality of light sources, such as e.g. 2-2000, such as 2-500, like 2-100, especially 4-80 (solid state) light sources, though many more light sources may be applied.
  • the term "light source” may also relate to one or more lightsources that are tailored to be applied for such light concentrating luminescent concentrators, e.g. one or more LED's having a long elongated radiating surface matching the long elengated light input surfaces of the elongated luminescent concentrator.
  • the term LED may also refer to a plurality of LEDs.
  • the term “solid state light source” may also refer to a plurality of solid state light sources. In an embodiment (see also below), these are substantially identical solid state light sources, i.e. providing substantially identical spectral distributions of the solid state light source radiation.
  • the solid state light sources may be configured to irradiate different faces of the light transmissive body.
  • the term “light source” may in embodiments also refer to a so-called chips-on-board (COB) light source.
  • COB especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB or comparable. Hence, a plurality of semiconductor light sources may be configured on the same substrate.
  • a COB is a multi LED chip configured together as a single lighting module.
  • the lighting device comprises a plurality of light sources.
  • the light source light of the plurality (m) of light sources have spectral overlap, even more especially, they are of the same type and provide substantial identical light (having thus substantial the same spectral distribution).
  • the light sources may substantially have the same emission maximum ("peak maximum"), such as within a bandwidth of 10 nm, especially within 8 nm, such as within 5 nm (e.g. obtained by binning).
  • the lighting device may comprise a single light source, especially a solid state light source having a relatively large die.
  • the phrase "one or more light sources" may be applied.
  • the light sources are especially configured to provide a blue optical power (Wopt) of at least 0.2 Watt/mm 2 to the light transmissive body, i.e. to the radiation input face(s).
  • the blue optical power is defined as the energy that is within the energy range that is defined as blue part of the spectrum (see also below).
  • the photon flux is in average at least 4.5* 10 17 photons/(s.mm 2 ), such as at least 6.0* 10 17 photons/(s.mm 2 ).
  • this may e.g. correspond to a blue power (W op t) provided to at least one of the radiation input faces of in average at least 0.067 Watt/mm 2 and 0.2 Watt/mm 2 , respectively.
  • W op t blue power
  • the term "in average” especially indicates an average over the area (of the at least one of the radiation input surfaces).
  • each of these radiation input surfaces receives such photon flux.
  • the indicated photon flux (or blue power when blue light source light is applied) is also an average over time.
  • the plurality of light sources are operated in pulsed operation with a duty cycle selected from the range of 10-80%, such as 25-70%.
  • the plurality of light sources are operated in video signal content controlled PWM pulsed operation with a duty cycle selected from the range of 0.01-80%), such as 0.1-70%.
  • the plurality of light sources are operated in video signal content controlled intensity modulated operation with intensity variations selected from the range of 0.1-100%, such as 2-100%.
  • the lighting device may comprise a plurality of luminescent concentrators, such as in the range of 2-50, like 2-20 light concentrators (which may e.g. be stacked).
  • the light concentrator may radiationally be coupled with one or more light sources, especially a plurality of light sources, such as 2-1000, like 2-50 light sources.
  • the term "radiationally coupled” especially means that the light source and the light concentrator are associated with each other so that at least part of the radiation emitted by the light source is received by the light concentrator (and at least partly converted into luminescence).
  • the luminescent concentrator receives at one or more radiation input faces radiation (pump radiation) from an upstream configured light concentrator or from upstream configured light sources.
  • the light concentrator comprises a luminescent material configured to convert at least part of a pump radiation received at one or more radiation input faces into luminescent material light, and the luminescent concentrator configured to couple at least part of the luminescent material light out at the radiation exit window as converter light. This converter light is especially used as component of the lighting device light.
  • the converter light, downstream of the radiation exit window comprises at least the luminescent material light escaped via the radiation exit window from the light converter.
  • the term “converter light” also the term “light concentrator light” may be used.
  • Pump radiation can be applied to a single radiation input face or a plurality of radiation input faces.
  • the length (L) is selected from the range of 1-100 cm, such as especially 2-50 cm, like at least 3 cm, such as 5-50 cm, like at maximum 30 cm. This may thus apply to all luminescent concentrators. However, the range indicates that the different luminescent concentrators may have different lengths within this range.
  • the elongated light transmissive body comprises an elongated ceramic body.
  • luminescent ceramic garnets doped with Ce 3+ can be used to convert blue light into light with a longer wavelength, e.g. within the green to red wavelength region, such as in the range of about 500-750 nm.
  • transparent rods especially substantially shaped as beams.
  • Such rod can be used as light concentrator, concentrating over their length light source light from light sources such as LEDs (light emitting diodes), converting this light source light into converter light and providing at an exit surface a substantial amount of converter light.
  • Lighting devices based on light concentrators may e.g. be of interest for projector applications.
  • red, green and blue luminescent concentrators are of interest.
  • Green luminescent rods, based on garnets can be relatively efficient.
  • Such concentrators are especially based on YAG:Ce (i.e. Y 3 Al 5 0i2:Ce 3+ ) or LuAG (Lu 3 Al 5 0i 2 :Ce 3+ ).
  • YAG:Ce i.e. Y 3 Al 5 0i2:Ce 3+
  • LuAG Lu 3 Al 5 0i 2 :Ce 3+
  • 'Red' garnets can be made by doping a YAG-garnet with Gd ("YGdAG").
  • Blue luminescent concentrators can be based on YSO (Y 2 Si05:Ce 3+ ) or similar compounds or BAM (BaMgAli 0 Oi7:Eu 2+ ) or similar compounds, especially configured as single crystal(s).
  • the term similar compounds especially refer to compounds having the same crystallographic structure but where one or more cations are at least partially replaced with another cation (e.g. Y replacing with Lu and/or Gd, or Ba replacing with Sr).
  • anions may be at least partially replaced, or cation-anion combinations, such as replacing at least part of the Al-0 with Si-N.
  • the elongated light transmissive body comprises a ceramic material configured to wavelength convert at least part of the (blue) light source light into converter light in e.g. one or more of the green, yellow and red, which converter light at least partly escapes from the radiation exit window.
  • the ceramic material especially comprises an A 3 B 5 0i2:Ce 3+ ceramic material ("ceramic garnet"), wherein A comprises yttrium (Y) and gadolinium (Gd), and wherein B comprises aluminum (Al).
  • A may also refer to other rare earth elements and B may include Al only, but may optionally also include gallium.
  • the formula A 3 BsOi 2 :Ce 3+ especially indicates the chemical formula, i.e. the stoichiometry of the different type of elements A, B and O (3:5: 12). However, as known in the art the compounds indicated by such formula may optionally also include a small deviation from stoichiometry.
  • the invention also provides such elongated light transmissive body per se, i.e. an elongated light transmissive body having a first face and a second face, these faces especially defining the length (L) of the elongated light transmissive body, the elongated light transmissive body comprising one or more radiation input faces and a radiation exit window, wherein the second face comprises the radiation exit window, wherein the elongated light transmissive body comprises a ceramic material configured to wavelength convert at least part of (blue) light source light into converter light, such as (at least) one or more of green, yellow, and red converter light (which at least partly escapes from the radiation exit window when the elongated light transmissive body is irradiated with blue light source light), wherein the ceramic material comprises an A3B 5 0i2:Ce 3+ ceramic material as defined herein.
  • Such light transmissive body can thus be used as light converter.
  • such light transmissive body has the shape of a cub
  • the ceramic material comprises a garnet material.
  • the elongated body especially comprises a luminescent ceramic.
  • the garnet material especially the ceramic garnet material, is herein also indicated as "luminescent material”.
  • the luminescent material comprises an A3B 5 0i2:Ce 3+ (garnet material), wherein A is especially selected from the group consisting of Sc, Y, Tb, Gd, and Lu (especially at least Y and Gd), wherein B is especially selected from the group consisting of Al and Ga (especially at least Al). More especially, A (essentially) comprises yttrium (Y) and gadolinium (Gd), and B (essentially) comprises aluminum (Al).
  • Such garnet is be doped with cerium (Ce), and optionally with other luminescent species such as praseodymium (Pr).
  • the element A may especially be selected from the group consisting of yttrium (Y) and gadolinium (Gd).
  • A3B 5 0i2:Ce 3+ especially refers to (Yi_ xGd x )3B50i2:Ce 3+ , wherein especially x is in the range of 0.1-0.5, even more especially in the range of 0.2-0.4, yet even more especially 0.2-0.35.
  • A may comprise in the range of 50-90 atom %Y, even more especially at least 60-80 atom %Y, yet even more especially 65- 80 atom % of A comprises Y.
  • A comprises thus especially at least 10 atom % Gd, such as in the range of 10-50 atom% Gd, like 20-40 atom%, yet even more especially 20-35 atom % Gd.
  • B comprises aluminum (Al), however, B may also partly comprise gallium (Ga) and/or scandium (Sc) and/or indium (In), especially up to about 20% of Al, more especially up to about 10 % of Al may be replaced (i.e. the A 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. Therefore, B may comprise at least 90 atom % Al.
  • A3B 5 0i2:Ce 3+ especially refers to (Yi_ x Gd x )3Al50i2:Ce 3+ , wherein especially x is in the range of 0.1-0.5, even more especially in the range of 0.2-0.4.
  • B (especially Al) and O may at least partly be replaced by Si and N.
  • B (especially Al) and O may at least partly be replaced by Si and N.
  • up to about 20 %> of Al-0 may be replaced by Si-N, such as up to 10%>.
  • n mole % Ce indicates that n% of A is replaced by cerium.
  • A3B 5 0i2:Ce 3+ may also be defined as (Ai-nCenbBsO ⁇ , with n being in the range of 0.001-0.035, such as 0.0015-0.01. Therefore, a garnet essentially comprising Y and mole Ce may in fact refer to ((Yi- x Gd x )i-nCe n )3B50i2, with x and n as defined above.
  • the ceramic material is obtainable by a sintering process and/or a hot pressing process, optionally followed by an annealing in an (slightly) oxidizing atmosphere.
  • the term "ceramic” especially relates to an inorganic material that is - amongst others - obtainable by heating a (poly crystalline) powder at a temperature of at least 500 °C, especially at least 800 °C, such as at least 1000 °C, like at least 1400 °C, under reduced pressure, atmospheric pressure or high pressure, such as in the range of 10 "8 to 500 MPa, such as especially at least 0.5 MPa, like especially at least 1 MPa, like 1 to about 500 MPa, such as at least 5 MPa, or at least 10 MPa, especially under uniaxial or isostatic pressure, especially under isostatic pressure.
  • a specific method to obtain a ceramic is hot isostatic pressing (HIP), whereas the HIP process may be a post-sinter HIP, capsule HIP or combined sinter-HIP process, like under the temperature and pressure conditions as indicate above.
  • the ceramic obtainable by such method may be used as such, or may be further processed (like polishing).
  • a ceramic especially has density that is at least 90% (or higher, see below), such as at least 95%, like in the range of 97-100 %>, of the theoretical density (i.e. the density of a single crystal).
  • a ceramic may still be poly crystalline, but with a reduced, or strongly reduced volume between grains (pressed particles or pressed agglomerate particles).
  • the heating under elevated pressure, such as HIP may e.g.
  • the heating under elevated pressures is preceded by a sintering process at a temperature selected from the range of HOODOO °C, such as 1500-1800 °C.
  • a sintering process at a temperature selected from the range of HOODOO °C, such as 1500-1800 °C.
  • Such sintering may be performed under reduced pressure, such as at a pressure of 10 "2 Pa or lower.
  • Such sintering may already lead to a density of in the order of at least 95%, even more especially at least 99%, of the theoretical density.
  • the light transmissive body especially refers to a sintered polycrystalline having a density substantially identical to a single crystal (of the same material). Such body may thus be highly transparent for visible light (except for the absorption by the light absorbing species such as especially Ce 3+ ).
  • the luminescent concentrator may also be a crystal, such as a single crystal. Such crystals can be grown / drawn from the melt in a higher temperature process. The large crystal, typically referred to as boule, can be cut into pieces to form the light transmissive bodies.
  • the polycrystalline garnets mentioned above are examples of materials that can alternatively also be grown in single crystalline form.
  • the body After obtaining the light transmissive body, the body may be polished. Before or after polishing an annealing process (in an oxidative atmosphere) may be executed, especially before polishing. In a further specific embodiment, the annealing process lasts for at least 2 hours, such as at least 2 hours at at least 1200 °C. Further, especially the oxidizing atmosphere comprises for example 0 2 .
  • luminescent materials may be applied, e.g. embedded in organic or inorganic light transmissive matrixes, as luminescent concentrator.
  • quantum dots and/or organic dyes may be applied and may be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc. etc...
  • Quantum dots are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots.
  • Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS).
  • Cadmium free quantum dots such as indium phosphode (InP), and copper indium sulfide (CuInS 2 ) and/or silver indium sulfide (AgInS 2 ) can also be used.
  • Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore the emission color can easily be tuned by adapting the size of the quantum dots. Any type of quantum dot known in the art may be used in the present invention. However, it may be preferred for reasons of environmental safety and concern to use cadmium- free quantum dots or at least quantum dots having a very low cadmium content.
  • quantum confinement structures should, in the context of the present application, be understood as e.g. quantum wells, quantum dots, quantum rods, or nano-wires.
  • Organic phosphors can be used as well.
  • suitable organic phosphor materials are organic luminescent materials based on perylene derivatives, for example compounds sold under the name Lumogen® by BASF.
  • suitable compounds include, but are not limited to, Lumogen® Red F305, Lumogen® Orange F240, Lumogen® Yellow F083, and Lumogen® F170.
  • the Stokes shift is relatively small.
  • the Stokes shift defined as the difference (in wavelength) between positions of the band maxima of the light source used for pumping and the light which is emitted, is not larger than 100 nm; especially however, the Stokes shift is at least about 10 nm, such as at least about 20 nm. This may especially apply to the light source light to first luminescent material light conversion, but also apply to the second pump radiation to second luminescent material light conversion, etc.
  • the plurality of light sources are configured to provide UV radiation as first pump radiation, and the luminescent concentrators are configured to provide one or more of blue and green first converter light. In yet other embodiments, the plurality of light sources are configured to provide blue radiation as first pump radiation, and the luminescent concentrators are configured to provide one or more of green and yellow first converter light. Note, as also indicated below, such embodiments may also be combined.
  • the lighting device may further comprise a cooling element in thermal contact with the luminescent concentrator.
  • the cooling element can be a heatsink or an actively cooled element, such as a Peltier element. Further, the cooling element can be in thermal contact with the light transmissive body via other means, including heat transfer via air or with an intermediate element that can transfer heat, such as a thermal grease. Especially, however, the cooling element is in physical contact with the light transmissive body.
  • the term "cooling element" may also refer to a plurality of (different) cooling elements.
  • the lighting device may include a heatsink configured to facilitate cooling of the solid state light source and/or luminescent concentrator.
  • the heatsink may comprise or consist of copper, aluminum, silver, gold, silicon carbide, aluminum nitride, boron nitride, aluminum silicon carbide, beryllium oxide, silicon-silicon carbide, aluminum silicon carbide, copper tungsten alloys, copper molybdenum carbides, carbon, diamond, graphite, and combinations of two or more thereof.
  • the term "heatsink” may also refer to a plurality of (different) heatsink.
  • the lighting device may further include one or more cooling elements configured to cool the light transmissive body.
  • cooling elements or heatsinks may be used to cool the light transmissive body and the same or different cooling elements or heatsinks may be used to cool the light sources.
  • the cooling elements or heatsinks may also provide interfaces to further cooling means or allow cooling transport to dissipate the heat to the ambient.
  • the cooling elements or heatsinks may be connected to heat pipes or a water cooling systems that are connect to more remotely placed heatsinks or may be directly cooled by air flows such as generated by fans. Both passive and active cooling may be applied.
  • the (first) elongated luminescent concentrator is clamped between 2 metal plates or clamped within a housing consisting of a highly thermal conductive material such way that a sufficient air gap between te (first) elongated
  • the luminescent concentrator remains present to provide TIR (tatal internal reflection) of the light trapped within the (first) elongated luminescent concentrator while a sufficient amount of heat may traverse from the (first) elongated luminescent concentrator through the air gap towards the highly thermal conductive housing.
  • the thickness of the air gap is higher than the wavelength of the light, e.g. higher than 0.1 ⁇ , e.g. higher 0.5 ⁇ .
  • the (first) elongated luminescent concentrator is secured in the housing by providing small particles between the (first) elongated luminescent concentrator and the houses, such as small spheres of rods having a diameter higher than 0.1 ⁇ , e.g. higher 0.5 ⁇ , preferably smaller than 1 ⁇ .
  • the (first) elongated luminescent concentrator may be secured in the housing by providing some suface roughtness on the surfaces of the highly thermal conductive housing touching the (first) elongated luminescent concentrator, the surface roughness varying over a depth higher than 0.1 ⁇ , e.g. higher 0.5 ⁇ , preferably smaller than 1 ⁇ .
  • an air gap may also comprise another gas than air, or may be vacuum.
  • the density of such spheres, rods or touch points of a rough surface of the highly thermal conductive housing is relatively very small, such most of the surface area of the (first) elongated light transmissive body remains untoutched securing a high level of TIR reflections within of the light trapped within the (first) elongated light transmissive body.
  • the lighting device may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, architectural lighting, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, green house lighting systems, horticulture lighting, or LCD backlighting, etc.
  • office lighting systems household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, architectural lighting, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, green house lighting systems, horticulture lighting, or LCD backlighting, etc.
  • the invention provides a projector comprising the lighting device as defined herein.
  • the light projector may also include a plurality of such lighting devices.
  • the invention also provides a lighting system
  • the invention also provides a lighting system as defined herein, wherein the lighting system comprises a digital projector, a stage lighting system or an architectual lighting system.
  • the lighting system may comprise one or more lighting devices as defined herein and optionally one or more second lighting devices configured to provide second lighting device light, wherein the lighting system light comprises (a) one or more of (i) the converter light as defined herein, and optionally (b) second lighting device light.
  • the invention also provides a lighting system configured to provide visible light, wherein the lighting system comprises at least one lighting device as defined herein. For instance, such lighting system may also comprise one or more
  • the lighting system may be, for example, a lighting system for use in an automotive application, like a headlight.
  • the invention also provides an automotive lighting system configured to provide visible light, wherein the automotive lighting system comprises at least one lighting device as defined herein and/or a digital projector system comprising at least one lighting device as defined herein.
  • the lighting device may be configured (in such applications) to provide red light.
  • the automotive lighting system or digital projector system may also comprise a plurality of the lighting devices as described herein.
  • the lighting device may be designed to provide high intensity UV radiation, e.g. for 3D printing technologies or UV streralization applications.
  • the lighting devize may be designed to provide a high intensity IR lightbeam, e.g, to project IR images for (military) training purposes.
  • white light herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2700 K and 6500 K, and for backlighting purposes especially in the range of about 7000 K and 20000 K, and 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, such as within about 3 SDCM from the BBL.
  • the terms "violet light” or “violet emission” especially relates to light having a wavelength in the range of about 380-440 nm.
  • blue light or “blue emission” especially relates to light having a wavelength in the range of about 440-490 nm (including some violet and cyan hues).
  • green light or “green emission” especially relate to light having a wavelength in the range of about 490-560 nm.
  • yellow light or “yellow emission” especially relate to light having a wavelength in the range of about 560- 570 nm.
  • range light or “orange emission” especially relate to light having a wavelength in the range of about 570-600.
  • red light or “red emission” especially relate to light having a wavelength in the range of about 600-780 nm.
  • pink light or “pink emission” refers to light having a blue and a red component.
  • visible or “visible emission” refer to light having a wavelength in the range of 380- 780 nm.
  • UV light may be UV-A (315-400 nm); UV-B (280-315 nm) or UV-C (200 - 280 nm).
  • IR light may be light in the range above 780 nm.
  • white light may in embodiments refer to light consisting of particular spectral compositions of wavalengths in the range between 380-780 nm, perceived nearby Plancks black body radiators having temperatures of about 1000 K and above.
  • Figs, la-le schematically depict some aspects of the invention; and Figs. 2a-2j schematically depict some embodiment.
  • a light emitting device 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.
  • 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.
  • FIG. la schematically depicts a lighting device 1 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 width W), which are herein also indicated as edge faces or edge sides 147.
  • 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/mm 2 .
  • 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.
  • 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.
  • the ceramic material 120 comprises an A3B 5 0i2:Ce 3+ 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 A3B 5 0i2:Ce 3+ .
  • 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.
  • the light source is an UV or violet light source, i.e.
  • 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.
  • 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. le). 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 lighting device 1 may be used as luminescent concentrator to pump another luminescent concentrator.
  • the lighting device 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 lighting devices 1 in Fig. lb further comprise a collimator 24, such as a CPC.
  • 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.
  • Fig. lc 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.
  • a lateral surface of the light guide should be understood as the outer surface or face of the light guide along the extension thereof.
  • the lateral surface is the side surface of the cylinder.
  • a lateral surface is also indicated with the term edge faces or side 140.
  • the variants shown in Fig. lc 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 ⁇ 5mm, in yet other embodiments ⁇ 2 mm.
  • the width W is in embodiments ⁇ 10 mm, in other embodiments ⁇ 5mm, 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.
  • 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.
  • the term "aspect ratio" refers to the ratio length/width.
  • Fig. lc schematically depicts an embodiment with four long side faces, of which e.g. two or four may be irradiated with light source light.
  • 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.
  • the radiation exit window is especially configured perpendicular to the radiation input face(s).
  • the radiation exit window and radiation input face(s) are configured perpendicular.
  • the radiation exit window may be configured relative to one or more radiation input faces with an angle smaller or larger than 90°.
  • 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.
  • a mirror may comprise a dichroic mirror.
  • Fig. Id very schematically depicts a projector or projector device 2 comprising the lighting device 1 as defined herein.
  • the projector 2 comprises at least two lighting devices 1, wherein a first lighting device (la) is configured to provide e.g. green light 101 and wherein a second lighting device (lb) 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.
  • 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).
  • the term "light source” may also refer to a plurality of different light sources.
  • the projector device 2 is an example of a lighting system 1000, which lighting system is especially configured to provide lighting system light 1001, which will especially include lighting device light 101.
  • High brightness light sources are interesting for various applications including spots, stage-lighting, headlamps and digital light projection.
  • 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.
  • High-brightness LED-based light source for beamer applications appear to be of relevance.
  • 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 refiection. At the exit facet of the rod the photons are extracted from the rod by means of some extraction optics, e.g.
  • CPC compound parabolic concentrator
  • micro- refractive structure micro-spheres or pyramidal structures
  • Fig. 2a schematically depicts a specific embodiment of the general embodiments. Examples of other embodiments are described also below with reference to Figs. 2b-2j.
  • Fig. 2a schematically depicts a lighting device 1 comprising a plurality of light sources 10 configured to provide light source light 11, a luminescent concentrator 5, a luminescent concentrator 5, and a second elongated light transmissive body 1100.
  • the luminescent concentrator 5 comprises a luminescent body 100 having a first face 141 and a second face 142 defining a length L of the light transmissive body 100.
  • the light transmissive body 100 comprises one or more radiation input faces 111 and a first radiation exit window 112.
  • the second face 142 comprises the first radiation exit window 112.
  • the luminescent body 100 comprises a luminescent material 120, such as YAG:Ce or a (garnet) variant thereon (see also above), configured to convert at least part of light source light 11 received at one or more radiation input faces 111 into luminescent material light 8.
  • the luminescent concentrator 5 is especially configured to couple at least part of the luminescent material light 8 out at the first radiation exit window 112 as converter light 101.
  • the first radation exit window 112 has a first radiation exit window surface area Al.
  • the luminescent concentrator 5 is optically coupled with the first radiation exit window 112.
  • the beam shaping optical element 224 comprises a radiation entrance window 211 configured to receive at least part of the converter light 101.
  • the radiation entrance window 211 has a radiation entrance window surface area A2 which is larger than the first radiation exit window surface area Al .
  • the beam shaping optical element 224 especially comprises a collimator 24.
  • the beam shaping optical element 225 comprises a light transmissive body 225 comprising the radiation entrance window 211, wherein the beam shaping optical element 224 comprises a compound parabolic collimator.
  • the lighting device 1 further comprises a second elongated light transmissive body 1100, configured parallel to the luminescent body 100, the second elongated light transmissive body 1100 having a first face 1141 and a second face 1142 defining a second length L2 of the second elongated light transmissive body 1100. In general, L2-L1.
  • the second eleongated light transmissive body 1100 comprises faces 1140, such as edge faces or edge sides 1147 (in analogy to the first elongated light transmissive bodye 100 comprising faces 140, such as edge faces or side faces 147; see also above). Also the second elongated light transmissive body 1100 comprises one or more radiation input faces 1111 (e.g. such side face 1147) for receiving at least part of the converter light 101 that escapes from one or more side faces 140 of the luminescent body 100, and a radiation exit window 1112.
  • faces 1140 such as edge faces or edge sides 1147
  • the second elongated light transmissive body 1100 comprises one or more radiation input faces 1111 (e.g. such side face 1147) for receiving at least part of the converter light 101 that escapes from one or more side faces 140 of the luminescent body 100, and a radiation exit window 1112.
  • the second face 1142 of the second elongated light transmissive body 1100 comprises the radiation exit window 1112.
  • the second radation exit window 1112 has a second radiation exit window surface area Al l .
  • the beam shaping optical element 224 is optically coupled with the second radiation exit window 1112, either via physical contact or via an optical glue (the same applies to the optical coupling with the luminescent body). Especially, 0.5 ⁇ (Al+Al 1)/A2 ⁇ 1.05.
  • the beam shaping optical element has a radiation entrance window 211 and a radiation exit window 212. The distance between the radiation entrance window 211 and the radiation exit window 212 defines a length of the light transmissive body 225 of the beam shaping optical element 224.
  • the index of refraction may be in the order of 1.8.
  • the second elongated light transmissive body may e.g. be glass or polymer.
  • Fig. 2b schematically depicts a basic variant, without a second elongated light transmissive body, but with a gas, especially air, neighbouring to the luminescent body 100.
  • rays that escape from the first elongated body 100 can still be captured by the radiation entrance window 211 for providing light 101 downstream of the beam shaping optical element 224.
  • a reflector may be used to generate a (kind of) cavity, herein also indciated as space, indicated with reference 1030.
  • the lighting device 1 further comprises a first reflective surface 1020 configured parallel to one or more side faces 140 and configured at a first distance dl from the luminescent body 100.
  • This first reflective surface 1020 is configured to reflect at least part of the converter light 101 that escapes from the one or more side faces 140 back into the luminescent body 100 or to the beam shaping optical element 224.
  • the space 1030 between the refelective surface 1020 and the one or more side faces 140 comprises a gas, such as air.
  • the a second elongated light transmissive body 200 may be configured parallel to the first elongated body 100 as schematically depicted in Fig. 2c.
  • the second elongated light transmissive body 1100 configured parallel to the luminescent body 100.
  • the beam shaping optical element 224 is optically coupled with the second radiation exit window 1112.
  • the second radation exit window 1112 has a second radiation exit window surface area Al 1 (see Fig. 2e), and in embodiments 0.5 ⁇ (Al+Al 1)/A2 ⁇ 1.05 (see Fig. 2e).
  • a first refiective surface may be available.
  • the second elongated light transmissive body 1100 is configured between the first elongated light transmissive body 100 and the first reflective surface. This may further enhance guiding the light to the one or more of a second elongated light transmissive body 1100, configured parallel to the first elongated light transmissive body 100, and a first reflective surface 1020 configured parallel to one or more side faces 140 of the first elongated light transmissive body 100 and the optional second elongated light transmissive body 1100. optical element 224. There may be an air gap between the first reflective surface 1020 and the second elongated light transmissive body.
  • Fig. 2d schematically depicts an embodiment wherein the second elongated light transmissive body 1100 includes facets for facilitating propagation of converter light escaping of the luminescent body 100 via the second elongated light transmissive body 1100 to the beam shaping optical element 224.
  • the lighting device 1 has a side face 140 of the luminescent body 100 configured parallel to a radiation input face 1111 of the second elongated light transmissive body 1100 (except for facets.
  • the radiation input face 1111 comprise facets 1030 for directing converter light 101 propagating from the first light transmissive body 100 to the second elongated light transmissive body 1100 in a direction of the beam shaping optical element 224.
  • the facets have an angle a relative to a plane parallel to the luminescent body 100.
  • This angle a may vary over the length L2 of the second elongated light transmissive body 1100, in order to increase even further the propagation of the converter light in the direction of the beam shaping optical element 224.
  • the value of a may increase with distance from the beam shaping optical element 224.
  • the facets may be provided by a transparent sheet comprising such facets, like a transparent sheet carrying prismatic structures, such as e.g. 3M Vikuiti Brightness Enhencement (BEF) films, 3M Optical Lighting Film 2405 or similars, which films may be present between the one or more elongated second elongated light transmissive elements 1100 and its corresponding luminescent body 100.
  • a transparent sheet comprising such facets, like a transparent sheet carrying prismatic structures, such as e.g. 3M Vikuiti Brightness Enhencement (BEF) films, 3M Optical Lighting Film 2405 or similars, which films may be present between the one or more elongated second elongated light transmissive elements 1100 and its corresponding luminescent body 100.
  • BEF Vikuiti Brightness Enhencement
  • a different arrangement of the second elongated light transmissive body 1100 and/or luminescent body 100 may also be possible, see Fig. 2f.
  • Fig. 2g again very schematiclaly shows an embodiment of the lighting device 1 with only the luminescent body 100. It is clear that the radiation entrance window 211 has a radiation entrance window surface area A2 which is larger than the first radiation exit window surface area Al . Further, for any embodiments - even though optionally depicted differently, the surface area of the radiation entrance window 211 is smaller than the surface area of the radiation exit window 212 of the beam shaping optical element 224.
  • Figs. 2h (and 2i) schematically depicts an embodiment of the lighting device 1 comprising a plurality of first elongated light transmissive bodies 100, configured parallel to each other.
  • Each of the first elongated light transmissive bodies 100 is configured to receive at least part of the light source light 11 of the plurality of light sources 10.
  • the one or more radiation input faces 1111 of the second elongated light transmissive body 1100 are configured for receiving at least part of the converter light 101 that escapes from one or more side faces 140 of the plurality of first elongated light transmissive bodies 100.
  • the first radiation exit window surface area Al is the accumulated first radiation exit window surface areas of each of the first elongated light transmissive bodies 100 of the plurality of first elongated light transmissive bodies 100; which is more clearly indicated in Fig. 2j. Between the two (or more) first elongated light transmissive bodies 100 there may a gap filled with a gas, or a gap at least partly filled with the second elongated light transmissive body 1100 as schematically depicted in Figs. 2h and 2j.
  • first light rays are light rays that are TIR (total internally reflected) at the boundary surfaces of a luminescent concentrator 100.
  • the converted light is trapped within the lighting device 1 and guided towards exit surfaces 142, 1142, 211, 212, where it may leave the lighting device as desired light into a desired direction.
  • a major part of the light will traverse in the one or more (first) elongated luminescent light transmissive bodys and/or the one or more second elongated light transmissive elements 1100 in the opposite direction.
  • a mirror 21 is positioned parallel to and facing the exit windows 141, 1141, etc., generally mirror 21 will have equal size as the area A2 of the entrance window 211 of the the beam shaping optical element 224.
  • Mirror 21 may contain a hole to allow source light, such as source light originating from a ble laser, to pass mirror 21 through that hole to enter the corresponding luminescent light transmissive body.
  • Converted light leaving the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100 at exit surfaces 142, 1142, 211, 212 will hirelect at the reflecting surface of mirror 21 back into the corresponding one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100, where it will traverse towards the opposite exit windows 141, 1141, 212 respectively and leave the lighting device as desired light into a desired direction 101.
  • converted light may leave the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100 at the other side faces, being the faces above and below the plane of paper of figures la till 2j, the surfaces of the one or more elongated concentrators 100 facing the lightsources 10 and the surfaces at the top side of the lighting devices 1.
  • (one or more) second reflective surfaces 2100 may be positioned parallel and nearby these surfaces (see Figs.
  • such light that may leave these surfaces towards an undesired direction will reflect at these mirror surfaces back into the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100. Since TIR reflections are preferred at the corresponding surfaces of the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100, these second reflective surfaces 2100 are not in optical contact with the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100.
  • These second reflective surfaces 2100 may be present as a highly reflective coating at the inner walls of the highly thermal conductive housing, keeping the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100 at their desired position.
  • the second reflective surfaces 2100 contain openings (holes), such that the light emitted by the lightsources 10 may pass its corresponing second reflective surface and hit/enter the elongated concentrators 100 such it may exite the phospor material present in the elongated concentrators 100.
  • This is shown in Fig. 2h with reflective surfaces 2121, which can be considered a specific embodiment of the second reflective surface.
  • Reference 2310 refers to e.g. a PCB, carrying the light sources (light sources 10 not depicted in Fig. 2i).
  • Fig. 2i is a cross-sectional view along the dashed line in Fig. 2h.
  • the second reflective located at the surfaces facing the lightsources 10 may be present as highly reflective coatings at the PCB material carrying the lightsources 10.
  • Reflectors 21, first reflective surfaces 1020, and second relective surfaces 2100 may be specular and highly reflective surfaces, such as Alanod mirrors having a reflectivity above 98%, Optics Balzers Silflex mirrors having a reflectivity above 98%, 3M Solar Mirror Film 1100 having a reflectivity above 98%, or a coated silver mirror having a reflectivity above 98%.
  • reflecting surfaces 21 are flat mirrors, such the angular distribution of the light remains identical after reflection at these surfaces.
  • second reflective surfaces 2100 may contain micro groove structures, such the light rays are directed by the reflection at these surfaces towards a desired direction (the direction towards exit windows 141, 1141, 212 respectively; or towards directions causing the highest lightoutcoupling of the light rays reflected at these second reflective surfaces.
  • the micro groove structures at the second reflective surfaces 2100 may be saw tooth shaped micro grooves, such that the relections at each micro groove plane are specular reflections.
  • the angle of these micro groove structures may vary, such the angles increases while the microgrooves are further away from the exit windows 141, 1141, 212.
  • the microgroof structures at the second reflective surfaces 2100 may contain optical structures, such as curvatures or light focussing elements.
  • microgroove structures may be present on the faces of one or more elongated second elongated light transmissive elements 1100 facing the second reflecting surfaces.
  • the light reflectad at the secondary reflective surfaces may be directed by both (1) microgroove structures at the second reflective surfaces 2100 and (2) microgroof structures on the faces of one or more elongated second elongated light transmissive elements 1100 facing the second reflecting surfaces.
  • the second reflecting surfaces may consist of a transparent sheet carrying prismatic structures, such as e.g. 3M Vikuiti Brightness Enhencement (BEF) films, 3M Optical Lighting Film 2405 or similars, which films may be present between the the one or more elongated concentrators 100 or one or more elongated second elongated light transmissive elements 1 100 and the highly thermal conductive housing.
  • BEF Vikuiti Brightness Enhencement
  • 3M Optical Lighting Film 2405 similars, which films may be present between the the one or more elongated concentrators 100 or one or more elongated second elongated light transmissive elements 1 100 and the highly thermal conductive housing.
  • one or more second reflective surfaces 2100 are configured at one or more of (a) one or more side walls of the one or more first elongated light transmissive bodys 100 configured to reflect light back into the one or more first elongated light transmissive bodies, (ii) one or more side walls of one or more second elongated light transmissive elements 1 100 configured to reflect light back into the one or more second elongated light transmissive bodies 1 100.
  • one or more of the second reflective surfaces and the side walls the one or more second elongated light transmissive elements 1 100 comprise microgroove structures.
  • the second reflective surfaces 2100 may be positioned between the side walls of the one or more first elongated light transmissive bodys 100 and/or the one or more second elongated light transmissive element 1 100 and a housing (not depicted) used to position the one or more first elongated light transmissive bodys 100, and/or the one or more second elongated light transmissive element 1 100.
  • the second mirror and/or the side walls the one or more second elongated light transmissive element 1 100 facing a housing used to position the one or more first elongated light transmissive bodys 100 and/or the one or more second elongated light transmissive element 1 100 contain microgroof structures.
  • the adjective substantially may also be removed.
  • the term “substantially” 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%.
  • an absorption, a reflection or a transmission should be a certain value or within a range of certain values these values are valid for the intended range of wavelengths.
  • microstructures reflective microstructures or refractive microstructures
  • particular angles and sizes of microstructures may be optimized depending on particular dimensions, compositions and positioning of the one or more elongated concentrators 100 and/or the one or more elongated second elongated light transmissive elements 1100.
  • the invention further applies to a device 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.

Abstract

La présente invention concerne un dispositif d'éclairage (1) comprenant : - une ou plusieurs sources de lumière (10) conçues pour fournir une lumière de source de lumière (11) ; - un élément luminescent (5) comprenant un corps luminescent (100) ayant une première face (141) et une seconde face (142) définissant une longueur (L) du corps de transmission de lumière (100), le corps de transmission de lumière (100) comprenant une ou plusieurs faces d'entrée de rayonnement (111) et une première fenêtre de sortie de rayonnement (112), la seconde face (142) comprenant la première fenêtre de sortie de rayonnement (112) ; le corps luminescent (100) comprenant un matériau luminescent (120) conçu pour convertir au moins une partie de la lumière de source de lumière (11) reçue au niveau d'une ou de plusieurs faces d'entrée de rayonnement (111) en une lumière de matériau luminescent (8), et l'élément luminescent (5) étant conçu pour coupler au moins une partie de la lumière de matériau luminescent (8) à l'extérieur au niveau de la première fenêtre de sortie de rayonnement (112) en tant que lumière de convertisseur (101), la première fenêtre de sortie de rayonnement (112) ayant une surface de première fenêtre de sortie de rayonnement (A1) ; - un élément optique de mise en forme de faisceau (224) couplé optiquement à la première fenêtre de sortie de rayonnement (112), l'élément optique de mise en forme de faisceau comprenant une fenêtre d'entrée de rayonnement (211) conçue pour recevoir au moins une partie de la lumière de convertisseur (101), la fenêtre d'entrée de rayonnement (211) ayant une surface de fenêtre d'entrée de rayonnement (A2) supérieure à la surface de première fenêtre de sortie de rayonnement (A1).
PCT/EP2018/051844 2017-02-03 2018-01-25 Module concentrateur de lumière WO2018141625A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP17154518.9 2017-02-03
EP17154518 2017-02-03

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WO2018141625A1 true WO2018141625A1 (fr) 2018-08-09

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WO2020114817A1 (fr) * 2018-12-04 2020-06-11 Signify Holding B.V. Système de génération de lumière comprenant un corps luminescent allongé
JP2020101751A (ja) * 2018-12-25 2020-07-02 セイコーエプソン株式会社 光源装置およびプロジェクター
JP2020112643A (ja) * 2019-01-10 2020-07-27 セイコーエプソン株式会社 光源装置、プロジェクター及び蛍光体ロッド
WO2021052900A1 (fr) 2019-09-18 2021-03-25 Signify Holding B.V. Source de lumière à haute intensité à indice de rendu des couleurs élevé

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WO2016050687A1 (fr) * 2014-10-03 2016-04-07 Philips Lighting Holding B.V. Concentrateur de lumière à utiliser dans un dispositif d'éclairage
WO2016075014A1 (fr) 2014-11-11 2016-05-19 Koninklijke Philips N.V. Dispositif d'éclairage avec grenat céramique

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WO2006054203A1 (fr) 2004-11-18 2006-05-26 Philips Intellectual Property & Standards Gmbh Dispositif electroluminescent pourvu d'une structure de conversion
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WO2016050687A1 (fr) * 2014-10-03 2016-04-07 Philips Lighting Holding B.V. Concentrateur de lumière à utiliser dans un dispositif d'éclairage
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020114817A1 (fr) * 2018-12-04 2020-06-11 Signify Holding B.V. Système de génération de lumière comprenant un corps luminescent allongé
CN113167459A (zh) * 2018-12-04 2021-07-23 昕诺飞控股有限公司 包括细长发光体的光产生系统
US11604321B2 (en) 2018-12-04 2023-03-14 Signify Holding B.V. Light generating system comprising an elongated luminescent body
CN113167459B (zh) * 2018-12-04 2023-12-01 昕诺飞控股有限公司 包括细长发光体的光产生系统
JP2020101751A (ja) * 2018-12-25 2020-07-02 セイコーエプソン株式会社 光源装置およびプロジェクター
JP2020112643A (ja) * 2019-01-10 2020-07-27 セイコーエプソン株式会社 光源装置、プロジェクター及び蛍光体ロッド
WO2021052900A1 (fr) 2019-09-18 2021-03-25 Signify Holding B.V. Source de lumière à haute intensité à indice de rendu des couleurs élevé

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