WO2024052074A1

WO2024052074A1 - Illumination device and light conversion unit

Info

Publication number: WO2024052074A1
Application number: PCT/EP2023/072685
Authority: WO
Inventors: Frank Gindele; Christian RAKOBRANDT; Edgar Pawlowski; Rainer Graf
Original assignee: Schott Ag
Priority date: 2022-09-09
Filing date: 2023-08-17
Publication date: 2024-03-14
Also published as: DE102022123051A1

Abstract

The invention relates to an illumination device (100) comprising at least one light source (200) for emitting primary light (250), a main body (400), the main body (400) having a front side (410), and a light conversion element (300) which is attached to the front side (410) of the main body (400) and is configured to be illuminated with the primary light (250) emitted from the light source (200) and to emit secondary light (350) with a different wavelength, wherein the light conversion element (300) has a front side (310) facing away from the main body (400) and is configured to emit the secondary light (350) on the front side (310). The invention also relates to a light conversion unit comprising a light conversion element and an optical element (500).

Description

Lighting device and light conversion unit

The invention relates to a lighting device with a light source, a base body and a light conversion element applied thereto, as well as a light conversion unit with a light conversion element and an optical element.

Laser-based white light modules are described in the prior art. The principle of producing white light is based on the combination of blue light emission from a laser diode and light emission from a yellow-emitting converter material, also known as phosphor. The yellow light emission from the converter is caused by the blue laser radiation. The mixing of the blue laser light with the yellow light emission produces white light.

The basic principle is implemented in two configurations: the transmission arrangement and the remission arrangement. In the transmission arrangement, the blue laser light shines through the converter material. In the remission arrangement, the blue laser radiation is arranged in a reflection geometry relative to the converter material. Furthermore, the use of optical elements is known in order to direct the radiation emitted by the laser onto the converter material.

Some light-emitting devices are described, for example, in the following documents: US2016093779A1, JP2008251685A, US2019058303A, US2019032907A, US2018087726A, US2018058645A, US2017314768A, US2017284634A , US2017122505A and WO2013156444A1.

However, current solutions have some disadvantages, some of which will be listed below: One disadvantage is that the laser radiation often does not hit the converter material with ideal parameters and/or that the emitted radiation does not emerge with the desired parameters. These parameters can include, for example, the power density, the luminous efficacy, the spot size, the angle of incidence or the beam angle. Another disadvantage can be that when radiation is coupled in and out of the converter material, undesirable Fresnel losses often arise due to the jump in refractive index. Another disadvantage, for example, is that the converter material, especially in the area of the incident laser radiation, can pollute. Another disadvantage can be that the adjustment of optical elements, which are used to direct the laser radiation to the converter, is complex. In addition, the structure of known solutions is often relatively complex.

It is therefore an object of the invention to provide a lighting device and/or a light conversion unit in which such disadvantages are avoided. In particular, parameters of the radiation incident on the converter and/or the radiation emitted by the converter should be optimized (e.g. power density, luminous efficacy, spot size, angle of incidence, angle of radiation). Fresnel losses during coupling and decoupling should preferably be reduced. The converter should also preferably be protected from contamination. One aspect is also to avoid adjustment of optical elements and in particular to simplify the structure of a lighting device and/or a light conversion unit.

In particular, an arrangement and associated component for a laser-based lighting module for white light generation, preferably in an SMD arrangement, is sought, through which it is possible to direct the incident blue laser radiation onto the converter material and the emitted converted radiation from the converter with reduced Fresnel losses compared to air to be decoupled from the converter and in particular to be formed and mixed. This should be done without complex adjustment of various individual optical components and in a very compact manner. Furthermore, the arrangement should be usable for a hermetic housing or be part of it.

The invention relates to a lighting device comprising at least one light source, a light conversion element (also referred to as a converter, converter material, phosphor, etc.), which is designed to be illuminated with primary light and to emit secondary light with a different wavelength, and an optical element which is set up and/or arranged in such a way that both the primary light emitted by the light source passes through the optical element before the primary light hits the light conversion element, and the secondary light emitted by the light conversion element passes through the optical element before the secondary light leaves the lighting device. The lighting device is set up in particular to generate white light, but can can also be set up to produce other colors, both mixed colors and full colors being considered.

Preferably, the lighting device further comprises a base body, which is designed in particular as a heat sink, wherein the light conversion element is preferably arranged on the base body and/or is introduced into the base body.

The light conversion element is preferably connected to the base body via a connecting layer, the connecting layer preferably being formed from at least one adhesive, at least one glass, at least one ceramic adhesive or at least one metallic solder connection.

A base body that may be included has a front side, and the light conversion element can be applied to this front side. The light conversion element is preferably applied directly to the front of the base body. The light conversion element in turn has a front side, preferably facing away from the base body, and is designed to emit the secondary light on its front side.

The at least one light source is designed and/or arranged to emit primary light for illuminating the light conversion element, wherein the light source is preferably designed as a laser light source. The light source is preferably designed to emit blue light and/or to emit UV light. It can be provided that the light source emits primary light with at least one wavelength in the range from 400nm to 470nm. A light source in the UVA range is also possible.

The light conversion element is designed in particular as an optoceramic (OC). The light conversion element preferably comprises ceramic converter material. Such a configuration can be advantageous in order to enable a particularly high light intensity even for white light. Ceramic converter materials are particularly temperature-stable and heat-conducting, meaning that particularly high luminance levels can be achieved. Organic-based converters or combinations of organic and ceramic converter materials are also conceivable. In particular, it is possible for the converter to be designed in such a way that it comprises a converter element which comprises two or more converter materials, which can in particular be designed so that they convert primary light into light of different spectral composition. For example, it is conceivable that a converter element comprises a so-called “yellow” and a so-called “red” phosphor. For example, these materials can be present as a mixture, for example as a mixture comprising an organic and a ceramic material, or as a mixture of organic or ceramic materials. However, the converter can also be designed in such a way that it comprises a plurality of converter elements, each of which comprises a different converter material. Mixtures of these versions are also conceivable.

In particular, the ceramic converter material can be or include a luminescent ceramic material. In the context of the present disclosure, this means that the converter can, for example, consist predominantly, i.e. at least 50% by weight, or essentially, i.e. at least 90% by weight, of a luminescent ceramic material. It is also possible for the converter to consist entirely of the luminescent ceramic material. In particular, the converter and/or the converter element comprises or consists of a luminescent ceramic material. The converter and/or the converter element can also be designed as a composite material, for example as a phosphorus-glass composite, or as a phosphorus-plastic composite, in particular phosphorus-silicone composite, or as a phosphorus-ceramic composite and in this case can for example at least 10% by weight of at least one luminescent material, i.e. phosphors, for example between 10% by weight and 30% by weight, in particular between 10% by weight and 20% by weight.

According to one embodiment, the converter and/or the converter element comprises a garnet-like ceramic material as a luminescent ceramic material or consists predominantly, i.e. at least 50% by weight, or essentially, i.e. at least 90% by weight, or completely of this, wherein the garnet-like ceramic material preferably has the following molecular formula: A3B50i2:RE, where

AY and/or Gd and/or Lu as well as B AI and/or Ga and wherein RE is selected from the group of rare earths and preferably comprises Ce and/or Pr.

According to yet another embodiment, the garnet-like ceramic material has the following molecular formula:

(Yi-xCex)3Al50i2 and/or

(Yi-x-yGd _y Cex)3AI ₅ 0i2 and/or

(Lui-xCe _x )3Al50i2 and/or

(Y i-x-zLuzCex)3Al50i2 , where the following applies to x: 0.005 < x < 0.05 and where the following applies to y: 0 < y < 0.2, and where the following applies to z: 0 < z < 1 .

According to one embodiment, the converter and/or the converter element comprises a luminescent ceramic material or consists predominantly, i.e. at least 50% by weight, or essentially, i.e. at least 90% by weight, or completely of this, wherein the converter

- as a single-crystalline material

- is present as a single-phase solid ceramic (e.g. a so-called optoceramic, polycrystalline) and/or

- is present as a multi-phase solid ceramic and/or

- is present as a single-phase or multi-phase ceramic of certain porosity and/or

- is present as a composite material, such as a phosphor-glass composite (PIG) and/or a phosphor-silicone composite (PIS).

According to a further embodiment, the ceramic material also includes other oxidic compounds (except garnet compounds), as well as nitridic compounds, in particular from the group of aluminum oxynitrides and silicon aluminum oxynitrides.

According to a further embodiment, the converter and/or the converter element is designed as a porous sintered ceramic and the porosity is between 0.5% and 10%, preferably between 4% and 8%. The porosity refers to the volume. Preferably it is located average pore size between 400 pm and 1200 pm, preferably between 600 pm and 1000 pm and particularly preferably between 600 pm and 800 pm.

In the context of the present disclosure, a single-phase ceramic (e.g. an optoceramic) is understood to mean that at least 95% by volume of the crystals and/or crystallites comprised by the ceramic are the same crystal phase. The volume fraction of foreign phases is preferably significantly lower. In particular, even more than 96% by volume or more than 97% by volume or more than 98% by volume or even more than 99% by volume of the crystals and/or crystallites comprised by the ceramic can form the same crystal phase. It cannot be ruled out that a single-phase ceramic may still contain amorphous components. However, these are usually less than 5% by volume.

It can be particularly advantageous if the ceramic material is designed in such a way that the material has a thermal conductivity in the range of 5 W/mK to 200 W/mK. In this way, a particularly good separation of the thermal energy created or created during the conversion is possible, so that the conversion properties of the converter material only change slightly, if at all, during operation of the material.

In particular, the ceramic converter material can be designed to be polycrystalline.

It can be advantageous if the material is present homogeneously or essentially homogeneously, whereby a homogeneous design of the material preferably means that the material is present as a single-phase ceramic (or optoceramic).

As described, the lighting device comprises an optical element which is set up and/or arranged in such a way that both the primary light emitted by the light source passes through the optical element before the primary light hits the light conversion element, and the secondary light emitted by the light conversion element passes through the optical one Element passes through before it leaves the lighting device. In other words, the optical element is located in the beam path both before and after the light conversion element. This allows the optical element to be used jointly for the primary light and for the secondary light in an advantageous manner. The optical element therefore guides both the incoming light and the outgoing light. The outgoing light can also be a mixture of at least parts of the incoming light (primary light) with the generated secondary light, which is to be included in the following under the term secondary light, even if different proportions and emission characteristics exist for both.

In a preferred embodiment, the optical element, which preferably comprises or consists of glass, is applied to the light conversion element, in particular to the front of the light conversion element, for example by means of glass solder and/or a melting process. Apart from any solder material used, the optical element is preferably applied directly to the converter. The optical element and the light conversion element can therefore be coupled and form an assembly. The optical element and the light conversion element can preferably be materially connected to one another. By applying or connecting the optical element to the converter, the converter is advantageously protected from contamination.

The optical element and the light conversion element can be connected to one another in a form-fitting manner and/or connected in such a way that an optical interface G1 is formed between the optical element and the light conversion element, at which primary light from the optical element can be coupled into the light conversion element and secondary light from the light conversion element can be coupled into the optical element can be coupled in. Sometimes it can also be possible to couple primary light, in particular reflected primary light, from the light conversion element into the optical element at the interface G1.

The optical element further preferably has a surface which forms a second optical interface G2 to a surrounding medium. In particular, it can be provided that for a beam angle, in particular a beam angle relative to a normal to the front of the light conversion element, which is smaller than 70 °, and in particular at transverse electrical polarization (TE), the sum of the Fresnel losses at the interfaces G1 and G2 is lower than 0.2.

It can be provided that by direct melting or melting on, around or on the light conversion element or at least an intermediate layer, which is formed, for example, from at least one glass solder or at least one thin glass layer. Such intermediate layers can be applied or applied in advance to the light conversion element or the optical element or can be provided as, for example, a thin plate. The application can take place via appropriate coating processes, printing processes or in a sol-gel process. Sequences of intermediate layers as layers or platelets are also conceivable, with corresponding layers also being able to be applied to the platelets. These layers can have different refractive indices and thus further reduce the Fresnel losses between the converter material and the material of the optical element.

The optical element is advantageously adapted or largely adaptable in terms of its optical properties, in particular its refractive index, to the light conversion element. This refers to the refractive index of the converter element or, in a special version, to the refractive index of individual materials and components of the converter element.

The refractive index difference between the optical element and the light conversion element is less than 2, in particular less than 1.5, preferably less than 1, preferably less than 0.5, particularly preferably less than 0.2 (particularly in the case that the refractive index of the light conversion element is larger than that of the optical element).

The surface of the optical element can be designed as follows for optimization with regard to Fresnel losses, for example by a design method. First, the Brewster angle is calculated for the desired material pairing or the refractive indices. Based on a specification at which angle the light conversion element should be irradiated, a surface shape of the optical element and/or an arrangement of the laser can then be determined such that it irradiates the surface at the Brewster angle and/or the refracted beam at the desired angle hits the light conversion element. If at least one intermediate layer is introduced, this is also advantageously adapted or adaptable in terms of its refractive index, in particular to the Lickt conversion element. With regard to the optical element, its refractive index is then preferably the same, and particularly preferably not greater, than that of the intermediate layer. It is also possible to form a refractive power gradation, with more than one intermediate layer, so to speak, a refractive power gradient, from the light conversion element to the optical element.

In addition to adapting or coordinating the refractive values to one another, a direct connection, i.e. without any air gap, is possible for the lowest possible Fresnel losses, so that the light yield, light coupling of the primary radiation and light coupling of the secondary radiation and parts of the primary radiation can be improved.

In particular, it can be provided that the connection of the components light conversion element and optical element occurs almost or completely error-free in order to enable an efficient, stable and long-lasting lighting device. In other words, that their connection or bonding surface is flawless. Similar to contamination in a lighting device without an optical element applied directly to the light conversion element, defects in the composite can lead to a lighting device with an optical element on the light conversion element being disrupted or even destroyed, since the primary radiation, for example, is irradiated with high power onto small areas Overheating of contamination or defects, for example enclosed or enclosed particles or bubbles, can lead to, among other things, disruption of the function of the lighting device or the direct connection, possibly delamination or even destruction of the optical element and/or conversion element . The optical element can therefore be connected to the light conversion element in a form-fitting and/or cohesive manner directly or by means of intermediate layers. When the optical element is melted directly, the boundary layer that forms is understood as a boundary surface or transition zone; if intermediate layers are used, a boundary layer or transition region can be formed.

The optical element can only cover the surface of the light conversion element, cover it or at least partially cover its side surfaces enclose in sections or completely. Both on the surface of the optical element and/or the surface as well as the side surfaces of the light conversion element, solder layers and/or adhesion-promoting layers can be applied, which can be, for example, very thin (a few 10 to 100 nm) and essentially transparent to the primary and secondary radiation or at least their optical effect can be negligible, since, for example, they cannot be designed to filter or significantly weaken or change the primary or secondary light.

The optical element does not necessarily need to be applied to the light conversion element. In an alternative embodiment, the optical element can also be spaced from the light conversion element. In such a case, the optical element can be attached to the lighting device in another way, for example attached to the or a base body and/or attached to the or a housing. For this purpose, the housing can, for example, be designed in two parts, so that it has a base part and a cap part. The optical element can then be attached to the cap part. The optical element is preferably guided through the cap part, the optical element then closing an opening in the cap part. The housing is then obtained by joining the cap part and the base part, for example by gluing, welding or soldering. For example, a glass solder can be used to attach the optical element to the cap part.

If the optical element is not arranged directly adjacent to the light conversion element, an intermediate layer can be provided. This can be designed to be flexible and nestle against the optical element and the light conversion element like a cushion made of a material adapted to the refractive index.

On the side surfaces of the light conversion element, in the event that the primary radiation irradiates exclusively onto the surface of the light conversion element, these layers can also include translucent or opaque layers, for example metallic layers, to which, for example, a subsequent solder layer is attached when connecting the optical element and light conversion element connects. Furthermore, it is conceivable that the light conversion element is surrounded by a frame which at least partially or partially surrounds and/or projects beyond its side surfaces. Alternatively, the light conversion element can also be arranged or can be arranged in a cavity in the base body. The depth of the cavity can be designed such that the side surfaces are at least partially enclosed or such that the depth of the cavity exceeds the thickness of the light conversion element. Frames of this type can advantageously provide additional surfaces that improve the connection between the optical element and the light conversion element or generally improve the stability of the connection of the optical element or lighting device. Such frames or cavities or bodies in which they are located can be made, for example, from metals or ceramics and, for example, selected taking into account thermal parameters, such as their thermal conductivity. Advantageous combinations, particularly in the case of additional frames, are sometimes made of the same material as any base body.

The optical element can be coated at least in some areas on its outer surface, for example a side surface of the optical element that faces the interior of the housing can be coated at least in some areas. It can be provided that the coating has recesses in order to couple the primary light into the optical element and/or to couple out the secondary light. A coating can advantageously help to optimize the light guidance, reduce lost light and/or improve the light mixing (e.g. homogenization). In particular, light leakage into the interior of the housing can be avoided by coating at least in some areas.

In one embodiment it can also be provided that the optical element is tubular, for example cylindrical or conical. In this case, the optical element can have a circumferential wall which encloses the light conversion element. The wall can be mirrored on the inside. A lens closing the cavity can be arranged on the side of a tubular optical element facing away from the light conversion element. Although this embodiment does not need to primarily serve to reduce Fresnel losses, it can contribute in particular to the mixing and/or homogenization of the overall emitted light. In the event that the optical element is applied to the converter, this can advantageously reduce Fresnel losses with respect to the primary light, the laser radiation, and the secondary light generated.

In other words, with an applied optical element, Fresnel losses can be advantageously reduced both in the primary light and in the secondary light, i.e. both during coupling and decoupling. In addition, optical components can be saved. Advantages also include, for example, that components can be placed compactly in a laser module, for example, and/or the number of optical components used can be reduced, so that reflection and absorption losses are reduced. These are, for example, advantages over known solutions in which the optical elements for the coupling and beam shaping of the laser radiation and the optical elements for the coupling out of the radiation converted in the converter material are separated from one another.

In a further embodiment it can also be provided that the optical element is provided with an anti-reflective layer (AR coating). The anti-reflective layer can consist of at least one thin layer or multiple layers. Usable processes for producing thin coatings are dip coating, vapor deposition (PVD), atomic layer deposition (ALD), and/or sputtering processes (e.g. IBE, RIE). When using a single layer, the refractive index of the layer n(layer) must be smaller than the refractive index of the optical element n(element). A thin lambda/4 layer with a refractive index n (layer) = root n (element) is preferably used.

In particular, it is provided that the optical element has a volume area in which both the primary light emitted by the light source and the secondary light emitted by the light conversion element pass during operation of the lighting device. The optical element is also preferably monolithic, i.e. formed in one piece. In one embodiment, the optical element can be designed as a tube, in particular a mirrored tube. Such a tube can be filled with a medium so that a core-cladding system is formed. For example, the tube may comprise glass or be made of glass and filled with glass with a different refractive index.

In a preferred embodiment, the optical element is designed as a beam shaper for the secondary light emitted by the light conversion element, in particular for focusing and/or collimating the secondary light emitted by the light conversion element. It can be provided that the optical element also acts as a beam shaper for primary light (i.e. in particular white light) reflected by the light conversion element. Furthermore, the optical element can be designed as a beam shaper for changing the cross-sectional geometry of the secondary light emitted by the light conversion element. The optical element can also shape or guide any remaining portions of primary light that may be reflected or scattered by the converter.

The optical element can have a curved surface, with in particular a surface of the optical element facing away from the front of the light conversion element being curved. The curved surface is preferably convex in order to effect focusing, collimation and/or beam shaping of the secondary light emitted by the light conversion element.

Furthermore, the optical element can have an outer surface with a different cross-sectional area than the cross-sectional area of the light conversion element, for example a non-round, round or polygonal cross-sectional area of the outer surface. The optical element can have a cross-section that can be changed at least partially or in sections starting from or towards the light conversion element, in particular it can be essentially conical. In one embodiment, the optical element can also be designed as a diffractive optical element (DOE) on its surface facing away from the converter.

Alternatively or additionally, the optical element can be designed as a beam shaper for the primary light emitted by the light source, in particular for focusing and/or collimating the primary light emitted by the light source onto the light conversion element. It can therefore be provided in particular that the optical element acts both as a beam shaper for the incident light and as a beam shaper for the outgoing light. If that optical element acts as a beam shaper for the incoming and / or outgoing light, advantageous synergy effects can be achieved, for example additional components can be saved.

The optical element can in particular be arranged in such a way and/or have a refractive index adapted to the medium surrounding the optical element in such a way that the primary light emitted by the light source hits the light conversion element as a result of the refraction, preferably hits the center of it. In one embodiment, the surrounding medium of the optical element can be a solid, for example in that the housing is cast.

Furthermore, it can be provided that the optical element has, at least in some areas, side surfaces that run obliquely to the normal of the light conversion element, such that the refraction of the primary light is reduced during the transition into the optical element. In one example, the optical element can be partially or partially conically shaped.

It can be provided that the primary light source is arranged so that its light hits the converter perpendicularly. The primary light source PL can advantageously be arranged directly on the optical element, so that there is essentially no (air) gap between the primary light source and the optical element, or any gap is bridged with a coupling medium, which prevents or minimizes a jump in the refractive index in the gap, but at least reduced.

The basic body can basically take different shapes. For example, the base body can be shaped in such a way that a base protrudes from a base, the protruding base also being referred to as a base element and the base also being referred to as a base element.

The at least one base element preferably forms a support surface for the light source, such that the light source is applied to the support surface of the base element, the light source (apart from solder, adhesive, etc.) being applied in particular directly to the support surface of the base element. The floor element preferably forms a support surface for the light conversion element in such a way that the light conversion element is applied to the support surface of the floor element, the light conversion element (apart from solder, adhesive, etc.) being applied in particular directly to the support surface of the floor element.

The base body can in particular form a common holder for both the at least one light source and for the light conversion element. Accordingly, both the at least one light source and the light conversion element can be applied to the base body.

The support surface of the base element for the light source preferably runs obliquely to the support surface of the base element for the light conversion element, in particular in such a way that the support surface of the base element for the light source aligns the optical axis of the primary light emitted by the light source to the light conversion element, in particular through the optical element on the light conversion element.

The at least one light source and the light conversion element can be applied to the base body aligned with one another in such a way that the optical axis of the primary light emitted by the light source is directed directly, for example in a straight line, at the light conversion element or with a deflection (in particular caused by the optical element). the light conversion element is directed, which is less than 60 degrees, preferably less than 45 degrees, particularly preferably less than 30 degrees, even more preferably less than 15 degrees.

The geometry of the support surface of the base element, which preferably extends obliquely to the support surface of the base element, can be designed such that there is an angle of at least 5 degrees, preferably an angle of at least 10 degrees, between the normal of the support surface for the light source and the normal of the support surface for the light conversion element exists, particularly preferably an angle of at least 20 degrees, even more preferably an angle of at least 30 degrees. The base body, in particular the base element of the base body, can further have an indicator for positioning/orientation of the light conversion element, the indicator preferably being designed as an elevation or depression. With regard to this indicator, the German patent application DE 10 2019 121 508.0 is hereby incorporated by reference and the further features of the indicator disclosed there for positioning/orientation of the light conversion element on the base body are also deemed to be disclosed within the scope of this disclosure.

As already described, the light conversion element has a front side facing away from the base body and the lighting device and/or the light conversion element are set up so that the secondary light is emitted on the front side of the light conversion element. Preferably, the lighting device and/or light conversion element are further configured to illuminate the light conversion element on the front with the primary light emitted by the light source, such that the light conversion element on the front both receives the primary light and emits the secondary light. In other words, the lighting device has, in particular, a reflection geometry.

Alternatively or additionally, it can also be provided that the light conversion element is illuminated on an edge surface which forms the transition from the front to the back of the light conversion element.

The at least one light source is preferably located together with the light conversion element inside a common housing. Alternatively, provision can be made to accommodate the at least one light source in its own housing. It is conceivable, for example, to provide a beam splitter or a dichroic mirror through which the secondary light passes and through which the primary light emitted by the light source is directed to the light conversion element. Here, too, it is provided according to the invention that both the primary light and the secondary light are passed through the optical element.

In the event that an optical element is provided, the lighting device and/or the light conversion element are also preferably set up to do so Light conversion element is illuminated on its front side with the primary light after passing through the optical element, so that the primary light emerging from the optical element hits the front side of the light conversion element.

In one embodiment, it can be provided that the light conversion element has a variable thickness, in particular in the middle through which the central axis runs, has a greater thickness than at an edge distant from the central axis, and / or has a convex front side. The light conversion element can also be wedge-shaped, for example.

The light conversion element can have the variable thickness in particular in the area of a primary light receiving surface and/or in the area of the secondary light emission surface, the primary light receiving surface designating that part of the light conversion element, in particular the front side of the light conversion element, in which the primary light strikes and the secondary light emission surface corresponding to that part of the front side of the Light conversion element refers to which the secondary light is emitted.

With regard to the variable thickness, German patent application 10 2019 121 507.2 is hereby incorporated by reference and the further features of the variable thickness of the light conversion element disclosed there are also deemed to be disclosed within the scope of this disclosure.

In one embodiment, it can further be provided that a light conversion arrangement is applied to the front of the base body, which comprises a plurality of light conversion elements, each of which is separated from one another at least in some areas by a trench.

With regard to the trench through which the light conversion elements are at least partially separated from one another, German patent application 10 2019.121 515.3 is hereby incorporated by reference and the further features of the trench disclosed there through which the light conversion elements are separated from one another at least partially also apply within the scope of this disclosure disclosed. In a further development of the invention, the lighting device comprises at least two light sources which are designed to emit primary light for illuminating the light conversion element. When using more than one light source, the light sources are preferably designed such that the wavelengths of the different light sources are preferably slightly different.

In this development, the base body preferably has a shape with at least two, for example opposite, base elements, each of which includes a support surface for one of the light sources. The additional features already described apply accordingly to each of the two support surfaces. In particular, the support surfaces of the base elements for the light sources can each run obliquely to the support surface of the base element for the light conversion element. It can be provided that the support surfaces of the base elements for the light sources each align the optical axis of the primary light emitted by the light source with the light conversion element, in particular align the optical axis running through the optical element with the light conversion element.

Preferably, the base body has such a shape that it simultaneously forms a housing for the lighting device, wherein the housing preferably encloses, in particular hermetically encloses, the at least one light source, in particular the at least two light sources, and the light conversion element, wherein the housing preferably has a window through which the secondary light emitted by the light conversion element can leave the housing.

As described, a base body of the lighting device forming the housing preferably has a window through which the light can escape to the outside. In principle, the window can be designed as an opening in the housing, for example as an end that is open at the front. In particular, in the case that the housing is hermetically designed, the housing preferably also has a transparent component, which at least partially forms the window of the housing. The transparent component can be designed, for example, as a glass pane. The transparent component can have a curved surface, for example a convex surface, in particular on the outside of the lighting device. Alternatively or additionally, the optical element can also be at least partially the window of the housing form, in particular in such a way that the optical element penetrates the housing and/or has a surface which faces outwards, which can in particular be the curved surface which, for example, effects collimation or focusing. The transparent component is preferably coated with at least one anti-reflective layer. The housing can also be designed in several parts and, for example, include a base part and a cap part. The cap part can, for example, be designed in the shape of a pot, wherein the window and/or the optical element can be arranged in a bottom surface of the pot shape.

The invention further relates to a light conversion unit comprising a light conversion element and an optical element, wherein in particular the features described above in connection with the lighting device can be implemented accordingly with respect to the light conversion element and the optical element.

The light conversion element is designed to be illuminated with primary light and to emit secondary light with a different wavelength, wherein the light conversion element is preferably designed to be illuminated with the primary light on a front side and to emit the secondary light in turn on the front side.

The optical element is set up so that both the primary light passes through the optical element before the primary light hits the light conversion element and the secondary light emitted by the light conversion element passes through the optical element.

The optical element preferably comprises glass or consists of glass and is particularly preferably applied to the front of the light conversion element, for example by means of glass solder and/or a melting process. The optical element and the light conversion element can be connected to one another in a form-fitting manner and/or connected in such a way that an optical interface G1 is formed between the optical element and the light conversion element, at which primary light from the optical element can be coupled into the light conversion element and secondary light from the light conversion element can be coupled into the optical element can be coupled in. The optical element further preferably has a surface which has a second optical interface G2 to a surrounding medium forms. In particular, it can be provided that for a beam angle, in particular a beam angle relative to a normal to the front of the light conversion element, which is smaller than 70 °, and in particular with transverse electrical polarization (TE), the sum of the Fresnel losses at the interfaces G1 and G2 is lower than 0.2.

The optical element of the light conversion unit is preferably set up and/or arranged in such a way that the optical element has a volume region in which both the primary light and the secondary light pass. The optical element can be monolithic.

The optical element can form a beam shaper for the secondary light emitted by the light conversion element, in particular for collimating/focusing the secondary light emitted by the light conversion element. Alternatively or additionally, the optical element can form a beam shaper for the primary light, in particular for collimating/focusing the primary light onto the light conversion element.

For this purpose, the optical element can have a curved surface, with the curved surface facing away from the front side of the light conversion element. The curved surface can be designed to be convex in order to bring about focusing of the secondary light emitted by the light conversion element.

The invention is explained in more detail below using a few figures. Show:

1 is a side sectional view of a lighting device,

2 is a side sectional view of a base body of a lighting device,

Fig. 3 is a side sectional view of a base body, which is a housing

lighting device forms,

4, 5 side sectional views of a lighting device with an optical element according to a first embodiment, 6, 7 side sectional views of a lighting device with an optical element according to a second embodiment,

8, 9 side sectional views of a lighting device with an optical element according to a third embodiment,

10, 11 side sectional views of a lighting device with an optical element according to a fourth embodiment,

12, 13 side sectional views of a lighting device with an optical element according to a fifth embodiment,

14 shows a light conversion arrangement as part of a lighting device with an optical element which is applied to a light conversion element,

Fig. 15 shows the Fresnel reflection for the primary light for interface transitions in each case for a glass material in relation to air, for the conversion material in relation to air and for the conversion material in relation to glass. The latter case corresponds to the interface between conversion material and optical element,

16 shows the summed Fresnel reflection for interface transitions for the primary light for the case with an optical element applied and, for comparison, without an optical element,

Fig. 17 shows the Fresnel reflection for interface transitions for the secondary light in each case for a glass material in relation to air, for the conversion material in relation to air and for the conversion material in relation to glass. The latter case corresponds to the interface between conversion material and optical element, 18 shows the summed Fresnel reflection for interface transitions for the secondary light for the case with an applied optical element and, for comparison, without an optical element,

19 shows a sectional view of a lighting device with a housing composed of a base part and a cap part,

20 shows the cap part of the lighting device shown in FIG. 19,

Fig. 21 shows a further embodiment of a cap part, and

Fig. 22 shows an exemplary embodiment of a two-part lighting device with a separately arranged light source.

Fig. 1 shows a lighting device 100 with two light sources 200 and a light conversion element 300 located between the two light sources 200, the two light sources 200 and the light conversion element 300 being attached to the front 410 of a base body 400 designed, for example, as a heat sink. The light sources 200 are arranged and aligned on the base body 400 in such a way that the optical axes of the primary light 250 emitted by the light sources 200 are directed towards the light conversion element 300.

The light conversion element 300 has a front side 310 facing away from the base body and is set up to be illuminated on its front side 310 with the primary light 250 and in turn to emit the secondary light 350 on its front side 310.

The base body further forms a housing 700, which encloses the light sources 200 and the light conversion element 300. The housing has a window 710 through which the secondary light 350 can leave the housing 700. At the same time, the base body preferably hermetically encloses a transparent component above the light conversion element 300 in order to form the window 710 and a hermetic seal on the top. Fig. 3 shows a base body, which forms a housing 700 again alone.

Fig. 2 shows the base body 400 with the light source(s) 200 and the light conversion element 300 embedded therein again alone. 1, the base body has a shape such that base elements 480 protrude from a base element 460, each of which forms a holder for the light sources 200. The light conversion element 300 is attached to the front 410 of the base body on the base element 460 between the two base elements 480. The base body 400 therefore forms a common holder for light sources 200 and light conversion element 300.

The base elements 480 each have a support surface 482 for supporting the light source 200 and the base element 460 has a support surface 462 for supporting the light conversion element 300, the support surfaces 482 of the base elements 480 running obliquely to the support surface 462 of the base element, such that the optical axis of the primary light 250 is directed towards the light conversion element.

4 to 11 show lighting devices 100 which partly have identical features to the embodiments already described. Furthermore, an optical element 500 is included, which is applied to the front side 310 of the light conversion element 300, such that both the primary light 250 and the secondary light 350 pass through the optical element 500. The optical element 500 forms a beam shaper for both the incoming primary light 250 and for the outgoing secondary light 350, with the convex outer surface 510 serving in particular for this purpose. At the same time, the optical element 500 forms protection for the front 310 of the light conversion element 300.

With this solution, in particular the laser radiation 250 as well as the emitted converter radiation 350 can be shaped with the optical element 500 and at the same time the Fresnel losses to the converter 300 can be reduced.

The optical element 500 made of glass is connected to the converter material 300, primarily an optoceramic (OC). The connection can be made via a direct melting process Glass material onto the light conversion element 300. The thermal expansion coefficients can preferably be adapted to one another. The difference in the expansion coefficients of the optical element 500 and the light conversion element 300 is preferably less than 5x10 ⁶ K' ¹ , particularly preferably less than 1x10 ⁶ K' ¹ . The glass element flows around the light conversion element 300 and forms a gap-free connection with the light conversion element 300. On the surface of the optical element 500, in particular the glass element, an optical surface, preferably a lens shape, is formed, which melts freely over itself via the surface energies. The connection between the light conversion element 300 and the optical element 500 can be additionally supported via a holding element made of ceramic, metal or glass or another material to guide the components. Likewise, the holding element, for example made of a metal with a subsequent solderable coating, can be used to connect the optical element to another component, such as a heat sink or the substrate of a hermetic housing.

The element consisting of light conversion element 300, optical element 500 and possibly holder is arranged in the laser module in such a way that the laser radiation is guided via the optical element 500 to the light conversion element 300. The laser radiation can be focused and/or the spot size can be changed and/or the laser radiation can be directed onto the light conversion element 300 via the optical element 500. The light converted in the OC is coupled out of the entire optical element via the optical element 500 and thus causes a decrease in the Fresnel losses compared to the direct coupling of the light radiation from the OC to air. At the same time, the radiation emitted by the light conversion element 300 is shaped by the optical element 500.

In addition to beam shaping, the optical element 500 can also cause light mixing. Different color coordinates, which are generated spatially and depending on the beam angle on the light conversion element 300, can be mixed with one another by the optical element 500 and thereby bring about homogenization. 9 and 10 show an embodiment in which the light conversion element 300 is formed on the surface. The light conversion element has a variable thickness, here a convex front side 310.

8 and 9 show an embodiment in which the converter is structured on the surface, for example divided into several elements. On the front 410 of the base body 400 there is a light conversion arrangement 305, which comprises a plurality of light conversion elements 300, each of which is separated from one another at least in regions by a trench 307.

In these embodiments too, the optical element 500 made of glass can be positively connected to the light conversion element 300 by a melting process.

10 and 11 show a lighting device 100 in which the optical element 500 at least partially forms the window 710 of the housing 700 and penetrates the base body 400 forming the housing 700.

12 and 13 show lighting devices 100 which correspond in many aspects to the lighting devices 100 shown in FIGS. 4 and 10, respectively. The optical element 500 here has a geometry adapted to reduce refraction. Specifically, in the examples shown, this is realized by a side surface 520 running obliquely to the normal of the light conversion element 300, the inclination of the side surface 520 being aligned such that the normal of the side surface 520 has a reduced angle to the optical axis of the primary light. According to the example shown in FIG. 12, the optical element can, for example, have a structured side surface with a plurality of oblique surfaces. According to the example shown in FIG. 16, the optical element can also be conical at least in sections.

19 shows a sectional view of a lighting device 100 with a multi-part housing 700 composed of a base part 701 and a cap part 702. The exemplary embodiment shown in FIG. 19 largely corresponds to the example described with reference to FIG. 10, but the optical element 500 is not direct here with the Light conversion element 300 connected. The optical element 500 is passed through an opening in the cap part 702 and attached to the cap part 702. The dimensions of the optical element 500 and the cap part 702 are selected so that the optical element 500 adjoins the light conversion element 300 as directly as possible after the base part 701 and cap part 702 have been joined. A remaining gap can be bridged, for example, with an intermediate element, which is preferably designed to be flexible, or with an immersion oil.

20 shows the cap part of the lighting device shown in FIG. 19 without the base part 701, compare FIG. 19. In this example, the optical element 500 is passed through an opening in the window 710 of the cap part 702. For this purpose, an opening can be provided in the window 710, through which the optical element 500 is passed. For example, by glazing the window 710 onto the optical element 500, the opening can be closed.

21 shows a further exemplary embodiment of a cap part 702. In contrast to the example in FIG. 20, no separate window 710 is provided in the cap part 702 in FIG. 21. The optical element 500 is passed directly through an opening in the cap part 702, which is designed, for example, as a deep-drawn metal part. For example, a glass solder can be used to glass the optical element 500 into the opening in the metal part. In the example shown in FIG. 21, the optical element 500 is adapted to a light conversion element 300 with a convex surface, as shown in FIGS. 6 and 7. Of course, it is possible to adapt the shape of the optical element 500 to any shape of a light conversion element 200.

22 shows an exemplary embodiment of a two-part lighting device 100 with a separately arranged light source 200. The light conversion element 300 and the optical element 500 are designed here similarly to the embodiment already described with reference to FIG. 10, but the base body 400 has no base elements 480, compare Figure 2. In this exemplary embodiment, the at least one light source 200 is not located within the housing 700, which accommodates the light conversion element 300, but is arranged separately from it and can have its own housing (not shown). In the one in Figure 22 In the embodiment shown, a dichroic mirror 202 is provided, with which primary light from the light source 200 is directed through the optical element 500 onto the light conversion element 300. Secondary light passes through the optical element 500 and through the dichroic mirror 202.

14 shows a light conversion unit with a light conversion element 300 and an optical element 500 applied thereon. The light conversion element 300 has a refractive index n3, the optical element 500 has a refractive index n2 and a medium 550 surrounding the optical element 500 has a refractive index n1 . There is a first interface G1 between the light conversion element 300 and the optical element 500 and there is an interface G2 between the optical element 500 and the surrounding medium 550. Primary light 250 passes through the optical element 500 before it hits the light conversion element 300 and secondary light emitted by the light conversion element 300 also passes through the optical element.

14 shows the general arrangement of the lighting unit without a primary light source, for example a laser, which can serve to illustrate the conditions when coupling in the primary light or its radiation power and coupling out in particular the secondary light, which is emitted from the light conversion element at least partial conversion of the primary light and possibly a remaining unconverted portion of the primary light, which is scattered out of the light conversion element or reflected from its surface in the direction of the lens or generally re-emitted.

An exemplary embodiment which shows the influence of the optical element in combination with the light conversion element compared to the case without an optical element is described below.

The respective light components pass through several refractive index ranges or hit them, penetrate into them, or emerge from them. Shown here are, for example, air or a surrounding medium 550 with refractive index n1, the or at least one optical element 500 with refractive index n2 and the or a light conversion element with refractive index n3. In some cases, as described above, it can also be at the transition from optical element 500 There is an interface or boundary layer with a further refractive index transition to the light conversion element 300.

In the present case according to FIG. 14, the primary light 250, in particular as a laser beam, first passes through an angle a through air 550, then through the optical element 500 and hits the light conversion element 300 or penetrates into it.

The secondary light generated in this way in or on the light conversion element 300 leaves the light conversion element 300 at or around the location of irradiation of the primary light essentially in Lambertian radiation and passes through the transition from the light conversion element with refractive index n3, reaches the optical element with refractive index n2 and finally reaches air with refractive index n1.

Unconverted primary light follows the path of the secondary light, depending on the properties of the light conversion element 300, such as surface and texture (pores, scattering centers, scattering properties, etc.), either as essentially following the law of reflection, or as reflected on the surface of the light conversion element, if necessary also with compared to the original primary light 250 widened beam angle, and / or as on or in the light conversion element 300 scattered, re-emitted primary light at or around the location of the irradiation of the primary light, the radiation of which can approach or correspond to a Lambertian radiation.

Provided that the primary light 250 is essentially a laser beam with a correspondingly small beam angle, Fresnel losses essentially come into play at the refractive index transitions. In the case of secondary light, depending on the radiation, additional or additional losses must be taken into account, which cannot leave the light conversion element in particular due to the refractive index conditions.

In other words, the paths of the radiant power of the laser and converted light are marked with the refractive indices n1, for example air, n2, for example a dielectric material such as glass, and n3, the light conversion material. The incident laser radiation (primary light) hits the optical element 300 at an angle of incidence a to the normal N of the interface G1. In a next step, the laser beam coupled into the glass hits the interface G2 between the glass and light conversion material with n3 at an angle of incidence a2.

When considering a vertical incidence of light radiation on flat interfaces, e.g. using a glass element on the converter material, depending on the adjustments of the refractive indices to one another, the Fresnel losses compared to air of over 20% can be reduced to Fresnel losses of well under 20% and under 16% during decoupling the light radiation from the converter element can be achieved. Furthermore, the change in the refractive index jump results in a change in the angle of total reflection. By reducing the jump in refractive index using an optical element on the converter material, this angle can be increased by a factor of up to 2 and beyond, thereby reducing reflection losses. The optical losses show different values for curved interfaces between the converter material and the glass element.

15 shows the reflection losses of the primary light as a function of the angle of incidence a at the respective interfaces. The chosen refractive indices here are, for example, n1=1, n2=1.5 and n3=3. The reflection losses are described here for the incident light waves with a perpendicular (TE) and parallel (TP) orientation to the plane of incidence. The two curves R_glas_TE and R_glas_TP result for the transition of laser radiation from air into glass. In general, reflection losses increase with the angle of incidence. In the case of parallel polarization, zero reflection occurs at a certain angle, the Brewster angle. A comparable course can be seen for the transition from glass to the light conversion material, R_GOC_TE and R_GOC_TP. The reflection losses are higher overall here due to the larger jump in refractive index. In addition, the reflection losses for the case without an optical element are shown R_OC_TE and R_OC_TP. These are largest over the angle of incidence a due to the higher jump in refractive index between n1 and n3.

The direct comparison of the Fresnel losses in the arrangement with and without an optical element is shown in Fig. 16. Here are the reflection losses when irradiated directly Light conversion element (R_OC_TE and R_OC_TP) and the summed reflection losses when using an optical element are shown (R_glas_TE+ R_GOC_TE and R_glas_TP+ R_GOC_TP). With an optical element, the reflection losses at, for example, a=0° are AR>5%, preferably >10% smaller compared to the reflection losses without an optical element. In this example, the reflection losses remain smaller up to an angle of incidence a~65-70° and then become larger.

In particular, it can be seen that for an angle of incidence a of the primary light 250 smaller than a certain angle (here, for example, approximately 70 ° C), the summed Fresnel losses at the interfaces G2 (transition n1 to n2) and G1 (transition n2 to n3) are lower than the Fresnel losses of a transition from n1 to n3, i.e. without an optical element. Against this background, but possibly also independently of this, one embodiment of the invention provides that the primary light 250 shines at an angle a to the normal N, which is smaller than 90°, in particular smaller than 85°, in particular smaller than 80 °, in particular is smaller than 75°, in particular is smaller than 70°, in particular is smaller than 60°, in particular is smaller than 45°.

Fig. 17 relates to the secondary light 350. If one considers, in other words, the decoupling of the radiation generated in the light conversion element, the reflection losses are basically described by Fig. 17. The decoupling of the light radiation from a light conversion element into the surrounding medium (i.e. without an additional optical element) is described by R_OC_TE and R_OC_TP. The reflection losses during the optical transition of the light radiation from the light conversion element into the optical element and during the transition from glass to air are respectively described by R_OC_glas_TE/TP and R_glas_TE/TP. The reflection losses at the R_OC_TE/TP transition are significantly higher compared to the others shown and are again strongly dependent on the angle.

In addition, the effect of total reflection can be seen. In total reflection, light radiation is completely reflected back into the optically denser material. In this case, the angle of total resection for the light conversion element is approximately a=20° (R_OC_TE and R_OC_TP) if no optical element is provided. The angle is larger for the other two cases (R_OC_glas_TE/TP and R_glas_TE/TP), ie when an optical element is provided. This means that when using an optical element on the Light conversion element increases the total reflection angle and thus enlarges the beam cone for light extraction. This increases the output light output. In Fig. 18 the summed reflection losses with an optical element are shown in comparison to the case without an optical element. For a=0°, using an optical element reduces the reflection losses by AR>5%, preferably >10%. The total reflection angle increases by Aa>5°, preferably >10°, in particular >15°. This makes an increased light output of AE >5%, preferably >10%, preferably >20% possible.

A number of advantages can therefore be achieved with the invention. In particular, beam shaping of the incident laser radiation and thus adaptation of the laser radiation to the requirements (higher power density, defined spot size, angle of incidence on phosphor). Furthermore, beam shaping of the emitted radiation from the phosphor (change in the radiation angle of the radiation through the optical element). Furthermore, Fresnel losses, which arise without an optical element due to the jump in refractive index from air to the phosphor during the transition of the laser radiation into the phosphor and the coupling of the emitted radiation from the phosphor, can be reduced with the present invention. Furthermore, the converting point with the highest power density can be protected from dirt from the environment. In addition, by applying the optical element to the light conversion element, an otherwise complex adjustment of optical elements to the laser and the converter can be avoided. By connecting the light conversion element to the optical element, the Fresnel losses and light trapped in the light conversion element due to total reflection can be reduced. In addition, components can be saved by using the optical element together for laser coupling and light extraction from the converter. In addition, the optical element can be used to shape the incoming and outgoing radiation, so that further components are saved.

With a construction of a lighting device with an applied optical element, further advantageous aspects can also be addressed. For example, in a structure without a direct connection between the optical element and the light conversion element, converted light is emitted unhindered in a Lambertian manner at least into a part of the half-space (+- 90° or 180°) and can be reflected and scattered by any surrounding elements. Something similar also applies on the remaining parts of the primary light, where there can be both directed (reflected with a certain direction) and Lambertian parts. In any case, at least part of the radiation emitted by the converter in a forward direction can, if necessary, be distributed contrary to possible requirements. This can result in less light being available at the location to be illuminated than is actually available. Furthermore, undesirable variations in the color temperature or luminous color can occur across the entire half-space, depending on how secondary light and primary light come together. Such color differences, in particular, are also referred to as color fringes or (color) halos and are often considered disruptive and are even hidden using, for example, additional shading elements or apertures, which leads to a further reduction in the available light.

If the lighting device is designed, for example, as in FIG. 1, this means that, depending on the design, significant portions of light can be emitted forward. In particular, secondary light but also parts of the primary light illuminate the entire housing (missing light, false light) and, as described above, these components can contribute less or not at all to the required lighting and, on the contrary, promote an inhomogeneous and incorrectly colored lighting impression on the output side of the lighting device. The entire luminous surface of such a lighting device can therefore be or appear larger than desired or necessary, in particular if a substantially point-shaped light source or one that comes close to this ideal is desired or required based on the lighting device.

This can be counteracted by means of an optical element spaced apart from the light conversion element, but here too only the light that can be detected by this element is, for example, collimated or guided, directed or distributed as required. Deficiencies in light output or color can therefore only be addressed to a limited extent. Color differences and other inhomogeneities, for example as or in the intensity curve, may only be shown more clearly.

In contrast, with an optical element applied directly to the converter, the secondary available radiation or light is essentially already detected at its origin and depending on the design of the connection and geometry of the optical element, provided more efficiently as required.

As described above, an arrangement itself, with an adapted optical design, can lead to a reduction in, for example, Fresnel losses and can already have a light or color mixing effect.

Further advantageously, the radiation into the half-space can be further reduced or even essentially eliminated, particularly via the length, shape and/or aftertreatment, for example by partial or sectional coating (or cladding), and thus a larger proportion of the secondary light can be targeted can be provided as required. In other words, missing or false light is at least reduced.

If, for example, as in Figures 10 and 11, a longer optical element is provided, which also encloses the edges of the light conversion element, secondary light and remaining portions of the primary light can be guided, guided and also in accordance with the design (in particular the refractive indices, but also geometry). be modified so that sometimes more light can be provided for the lighting, the lighting device can be more efficient overall. The guidance of the light in the optical element can also contribute to a homogenization and/or mixing of the light components, for example light of different wavelengths, and thus to homogeneous illumination with high color fidelity. The design of the optical element on the side facing away from the light conversion element can be designed variably and can be adapted or designed to be adaptable to a desired illumination or illumination. The lighting device can thus at least come close to a point light source.

The optical element can advantageously include further measures or features to further improve these aspects. It is conceivable to cover the optical element at least partially or in sections with a cladding, in the sense of a fiber-optic core-sheath element, or a coating, for example a mirror coating, which further promotes the reflection of light within the optical element or the escape of light to prevent total reflection within. When using a coating, it should be noted that this allows the primary radiation to enter the optical element. For example, by leaving out corresponding points and/or by designing the coating to be wavelength-selective, so that primary light can pass into the optical element but can no longer exit. The latter can also be provided for the secondary light.

In a further embodiment it can be provided that the optical element is at least partially or partially hollow, for example tubular or designed as a blind hole.

Its end facing away from the light conversion element can remain open, be fused or closed off with another element. The latter can be plate-shaped but also provided with at least one curvature, up to a sphere, so that it further contributes to the beam shaping of the light in a suitable manner.

It will be apparent to the person skilled in the art that the above-described variants can in principle also be transferred to other variants shown in the figures, or are not limited to them.

The optical element can also be designed in a cross-sectional geometry other than essentially round, for example rectangular, square, polygonal or with different radii of curvature, for example oval. The cross-sectional geometries can advantageously also be designed so that they are not constant along the length of an optical element. Versions to facilitate the coupling of the primary light are already shown and described in Figures 12 and 13. It was also shown that with the cross-section of the optical element continuously changing over its length, the radiation characteristics, in particular of Lambertian secondary light, can be narrowed (cross-section increasing from bottom to top) or, conversely, expanded. This is particularly important if the optical element is not monolithic, but is composed as a fiber-optic component from a plurality or plurality of light-conducting elements.

Many of the aforementioned measures and implementations contribute to opening up possibilities for adapting such a lighting device to its application. Examples here include coupling into other optical components or structures, in particular projection devices or fiber optics, or the targeted illumination of surfaces in a predetermined manner, including in terms of shape and sharpness. Intensity or intensity distribution or homogeneity or coloring.

Furthermore, particularly in the embodiments according to Figures 10, 11, 13, the window can advantageously also be designed to be translucent or opaque, colored or achromatic, which in turn can minimize or prevent any stray light from escaping to the front.

In summary, the invention enables in particular a compact structure, a reduction in the Fresnel losses on the surfaces and a reduction in the surfaces on which the laser light and the white light generated are reflected, a simple adjustment of the components to one another and a reduction of the components that are adjusted to one another, a collimation or .Focusing the laser radiation on the optoceramic, collimating or beam shaping the white light radiation, as well as mechanical protection of the position of generating high power densities on the optoceramic with glass. The invention is particularly suitable for LED modules, laser modules, for generating white light.

It will be apparent to those skilled in the art that the embodiments described above are to be understood as examples and the invention is not limited to these, but can be varied in many ways without departing from the scope of protection of the claims. The description of features of one exemplary embodiment also applies to the other exemplary embodiments.

Claims

1 . Illumination device (100), in particular for generating white light, comprising: at least one light source (200) for emitting primary light (250), in particular for emitting blue or ultraviolet laser light, a light conversion element (300) with a front side (310), wherein the Light conversion element (300) is designed to be illuminated with the primary light (250) emitted by the light source (200) and to emit secondary light (350) with a different wavelength on its front side (310), and an optical element (500), which set up so that both the primary light (250) emitted by the light source (200) passes through the optical element (500) before the primary light (250) hits the light conversion element (300), as well as the secondary light emitted by the light conversion element (300). (350) passes through the optical element (500) before the secondary light (350) leaves the lighting device (100).

2. Illumination device (100), according to the preceding claim, wherein the optical element (500) is provided with an anti-reflection layer (AR coating) and the anti-reflection layer preferably consists of at least one thin layer.

3. Lighting device (100) according to one of the preceding claims, wherein the optical element (500) preferably comprises glass and is particularly preferably applied to the front side (310) of the light conversion element (300), in particular by means of glass solder and / or a melting process, and / or wherein the optical element (500) and the light conversion element (300) are connected to one another in a form-fitting manner and/or are connected in such a way that an optical interface (G1) is formed between the optical element (500) and the light conversion element (300), at which Primary light (250) from the optical element (500) can be coupled into the light conversion element (300) and secondary light (350) from the light conversion element (300) can be coupled into the optical element (500), and / or wherein the optical element (500) is a Surface which forms a second optical interface (G2) to a surrounding medium (550), and / or wherein for at least one beam angle, in particular a beam angle opposite a normal of the front side of the light conversion element which is smaller than 70°, and in particular with transverse electrical polarization (TE), the sum of the Fresnel losses at the interfaces G1 and G2 is lower than 0.2.

4. Lighting device (100) according to one of the preceding claims, wherein the optical element (500) has a volume area in which both the primary light (250) emitted by the light source (200) and the secondary light emitted by the light conversion element (300) ( 350), and/or wherein the optical element (500) is monolithic.

5. Illumination device (100) according to one of the preceding claims, wherein the optical element (500) is designed as a beam shaper for the secondary light (350) emitted by the light conversion element (300), in particular for focusing and / or collimating the light emitted by the light conversion element (300 ) emitted secondary light (350) is designed, and / or is designed to change the cross-sectional geometry of the secondary light (350) emitted by the light conversion element (300) and / or wherein the optical element (500) is one, in particular the front (310) of the light conversion element (300) facing away from the curved surface (510), wherein the curved surface (510) is preferably convex in order to effect focusing and/or collimation of the secondary light (350) emitted by the light conversion element (300) and/or wherein the outer surface of the optical element (500) has a different cross-sectional area than that of the light conversion element (300), for example has a non-round, round or polygonal cross-sectional area and/or wherein the optical element (500) extends at least partially to or from the light conversion element (300). - or has a cross-section that can be changed in sections, in particular is essentially conical and / or wherein the optical element (500) is designed as a diffractive optical element on its surface facing away from the converter. Illumination device (100) according to one of the preceding claims, wherein the optical element (500) is designed as a beam shaper for the primary light (250) emitted by the light source (200), in particular for focusing and / or collimating the light emitted by the light source (200). Primary light (250) is formed on the light conversion element (300) and / or wherein the optical element has, at least in some areas, a side surface (520) which runs obliquely to the normal of the light conversion element (300), such that the refraction of the primary light (250) during the transition into the optical element (500) is reduced, the optical element being, for example, partially or partially conically shaped. Lighting device (100) according to one of the preceding claims, further comprising a base body (400) with a front side (410), the base body (400) being designed in particular as a heat sink, the base body (400) preferably having a shape that of a A base element (480) protrudes from the base element (460), the at least one base element (480) comprising a support surface (482) for the light source (200), such that the light source (200) rests on the support surface (482) of the base element (480 ) is applied, and/or wherein the base element (460) comprises a support surface (462) for the light conversion element (300), such that the light conversion element (300) is applied to the support surface (462) of the base element (460), and/ or wherein both the at least one light source (200) and the light conversion element (300) are applied to the base body (400), in particular in such a way that the base body (400) has a common holder for the at least one light source (200) and the light conversion element ( 300). Lighting device (100) according to one of the preceding claims, wherein the support surface (482) of the base element (480) for the light source (200) runs obliquely to the support surface (462) of the base element (460) for the light conversion element (300), in particular in such a way that that the support surface (482) of the base element (480) for the Light source (200) defines an alignment of the optical axis of the primary light (250) emitted by the light source on the light conversion element (300), in particular by the optical element (500) on the light conversion element (300), and/or wherein the at least one light source ( 200) and the light conversion element (300) are applied to the base body (400) aligned with one another in such a way that the optical axis of the primary light (250) emitted by the light source (200) is directed directly, for example in a straight line, towards the light conversion element (300) or with a deflection, in particular caused by the optical element (500), directed towards the light conversion element (300), which is less than 60 degrees, preferably less than 45 degrees, particularly preferably less than 30 degrees, even more preferably less than 15 degrees. Lighting device according to one of the preceding claims, wherein there is an angle of at least 5 degrees, preferably an angle of at least 10, between the normal of the support surface (482) for the light source (200) and the normal of the support surface (462) for the light conversion element (300). degrees, particularly preferably an angle of at least 20 degrees, even more preferably an angle of at least 30 degrees and/or wherein the base body (400), in particular the base element (460) of the base body (400), provides an indicator (450). Positioning/orientation of the light conversion element (300), wherein the indicator (450) is preferably designed as a survey or depression. Lighting device (100) according to one of the preceding claims, wherein the light conversion element (300) is set up to be illuminated on the front side (310) with the primary light (250) emitted by the light source, such that the light conversion element (300) on the Front side (310) receives both the primary light (250) and emits the secondary light (350) and/or wherein the light conversion element (300) is set up to form a transition from the front side (310) to the back side (320) of the light conversion element Edge surface (330) to be illuminated with the primary light (250) emitted by the light source. Lighting device (100) according to one of the preceding claims, wherein the light conversion element (300) has a variable thickness, in particular in the middle through which the central axis (600) runs, has a greater thickness than at an edge remote from the central axis (600). , and/or has a convex front side (310), and/or wherein a light conversion arrangement (305), which is applied in particular to the front side (410) of the base body (400), is included, which comprises a plurality of light conversion elements (300), which are each separated from one another at least in some areas by a trench (307). Lighting device (100) according to one of the preceding claims, comprising at least two light sources (200) which are designed to emit primary light (250) for illuminating the light conversion element (300), wherein the at least two light sources in particular have different wavelengths, and/or where the base body (400) preferably has at least two, for example opposite, base elements (480), each of which comprises a support surface (482) for one of the light sources (200), the support surfaces (482) of the base elements (480) for the light sources ( 200) preferably each run obliquely to the support surface (462) of the base element (460) for the light conversion element (300), in particular in such a way that the support surfaces (482) of the base elements (480) for the light sources (200) each correspond to the optical axis of the The primary light (250) emitted by the light source is aligned with the light conversion element (300), in particular aligned with the light conversion element (300) by the optical element (500). Lighting device (100) according to one of the preceding claims, wherein the base body (400) forms a housing (700) which encloses, in particular hermetically, the at least one light source (200), in particular the at least two light sources (200) and the light conversion element (300). encloses, and / or wherein the base body (400) forming the housing (700) has a window (710) through which the secondary light (350) emitted by the light conversion element (300) leaves the housing. Lighting device (100) according to one of the preceding claims, wherein the base body forming the housing (700) captures a transparent component which at least partially forms the window (710) of the housing (700) and/or wherein the optical element (500) at least partially forms the window (710) of the housing (700), in particular in such a way that the optical element penetrates the housing (700) and/or has a surface, in particular the curved surface (510), which faces outwards. Lighting device (100) according to one of claims 1 to 12, characterized in that the base body (400) is designed as a base part (701) and, together with a cap part (702), forms a housing (700), the cap part forming a window ( 710) and the cap part with the window (710) covers the optical element (500), or wherein the optical element (500) is passed through a through opening in the cap part (702). Lighting device (100) according to claim 15, characterized in that the optical element (500) is firmly connected to the cap part (702). Lighting device (100) according to one of claims 13 to 16, characterized in that the at least one light source (200) is arranged outside the housing (700). Lighting device (100) according to one of claims 1 to 17, characterized in that the optical element (500) directly adjoins the light conversion element (300), that an intermediate layer is arranged between the optical element (500) and the light conversion element (300), or that a gap is formed between the optical element (500) and the light conversion element (300). Light conversion unit comprising: a light conversion element (300), which is designed to be illuminated with primary light (250) and to emit secondary light (350) with a different wavelength, wherein the light conversion element (300) is preferably designed to be on a front side (310) to be illuminated with the primary light (250) and to emit the secondary light (350) on the front (310), and an optical element (500), which is set up so that both the primary light (250) passes through the optical element (500). , before the primary light (250) hits the light conversion element (300), and the secondary light (350) emitted by the light conversion element (300) passes through the optical element (500). Light conversion unit according to the preceding claim, wherein the optical element (500) preferably comprises glass and is particularly preferably applied to the front side (310) of the light conversion element (300), in particular by means of glass solder and/or a melting process, and/or wherein the optical element ( 500) and the light conversion element (300) are connected to one another in a form-fitting manner and/or are connected in such a way that an optical interface (G1) is formed between the optical element (500) and the light conversion element (300), at which primary light (250) emerges from the optical element (500) can be coupled into the light conversion element (300) and secondary light (350) from the light conversion element (300) can be coupled into the optical element (500), and / or wherein the optical element (500) has a surface which has a second optical interface (G2) to a surrounding medium (550), and/or wherein for at least one beam angle, in particular a beam angle relative to a normal to the front of the light conversion element which is smaller than 70°, and in particular with transverse electrical polarization (TE), the sum of the Fresnel losses at the interfaces G1 and G2 is lower than 0.2. Light conversion unit according to the preceding claim, wherein the optical element (500) has a volume region in which both the primary light (250) and the secondary light (350) extend and/or wherein the optical element (500) is monolithic. Light conversion unit according to one of the two preceding claims, wherein the optical element (500) is designed as a beam shaper for the secondary light (350) emitted by the light conversion element (300), in particular for focusing the secondary light (350) emitted by the light conversion element (300). , and/or wherein the optical element (500) has a curved surface (510), in particular facing away from the front side (310) of the light conversion element (300), wherein the curved surface (510) is preferably convex in order to enable focusing of the light conversion element (300). secondary light (350) emitted by the light conversion element (300) and/or wherein the optical element (500) is designed as a beam shaper for the primary light (250), in particular for focusing the primary light (250) on the light conversion element (300).