Light-emitting device and lamp

Abstract

The invention relates to a lighting device (1) having at least two LED units (Li, i = 1, 2, 3), each having: at least one LED chip (Ci) for generating primary light (Pi) having a primary spectrum; and a conversion element (Ki) for converting the primary light (Pi) into secondary light (Si) having a secondary spectrum having a greater spectral width than the primary spectrum. The secondary spectra of different ones of the at least two LED units (Li) are different.

Description

[0001] Cross Reference to Related Applications

[0002] The present patent application claims priority to German patent application DE 10 2023 206 079.5, the content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to a light emitting device, in particular in the form of an LED package. The invention further relates to a luminaire having at least one such light emitting device. BACKGROUND

[0004] Light emitting devices in the form of LED packages are known from prior use. These light emitting devices use one or more LED chips for emitting light. Due to the narrowband emission characteristics of LED chips, special means have to be taken for the generation of white light and mixed colors. It is for example known to combine LED chips of different colors. In particular, it is known to use red, green and blue LEDs in an LED package for generating white light. However, these so-called RGB LED packages, or simply RGB LEDs, have a non-uniform spectrum which leads to poor color rendering values.

[0005] In particular for the generation of white light, it is also known to convert the primary light of an LED chip into secondary light, for example white, by means of a light conversion material. However, the resulting spectrum is predetermined by the light conversion material used in each case and is thus not tunable. SUMMARY

[0006] It is an object of the present invention to improve a light emitting device, in particular to provide a light emitting device which has a high color rendering quality of the emitted spectrum and which has a high degree of flexibility with respect to the emitted spectrum.

[0007] This object is achieved by a light emitting device according to claim 1. The light emitting device, also referred to as light emitter, is in particular an LED package. It has at least two LED units. The at least two LED units each have at least one LED chip for generating primary light having a primary spectrum and a conversion element for converting the primary light into secondary light having a secondary spectrum, wherein the secondary spectrum has a greater spectral width than the primary spectrum. The secondary spectra of different LED units of the at least two LED units are different. The device combines the advantages of individual LED units with the broadband emission characteristics of the respective conversion element. This enables a more uniform, thus more color- faithful color mixing without being limited to the spectrum of one light conversion material.

[0008] The secondary light from the at least two LED units is superimposed to form the emitted light of the light-emitting device. In other words, the secondary spectra of the at least two LED units are superimposed to form the emitted spectrum. The emitted light having this emission spectrum is the light emitted by the device and ultimately perceived by the user. This emission spectrum specifically covers at least a portion of the visible light spectrum. The emission spectrum may also include portions of the infrared and / or ultraviolet ranges, depending on the application. Preferably, the emission spectrum is within the visible light wavelength range, particularly between 380 nm and 780 nm. Specifically, for the purpose of producing white light, the emission spectrum preferably covers at least 50% of the visible light wavelength range, and particularly at least 75% of the visible light wavelength range.

[0009] The secondary spectra are all different. They cover different sub-ranges of the wavelength range covered by the emission spectrum. Preferably, these secondary spectra are in the visible light range, particularly between 380 nm and 780 nm.

[0010] The primary light can be visible light (especially between 380 nm and 780 nm). The primary light can also have other wavelengths, particularly in the ultraviolet range. The primary light of an LED unit is converted into secondary light by a corresponding conversion element. Preferably, the wavelength of the primary light is selected such that good absorption and re-emission are achieved by the corresponding conversion element. Alternatively, the primary light can be selected such that the primary spectrum is entirely within the spectral range of the secondary spectrum. This reliably avoids false colors in the emission spectrum caused by unconverted primary light.

[0011] The spectral width of the secondary spectrum is greater than that of the corresponding primary spectrum. The spectral width is particularly the emission linewidth, and especially the full width at half maximum (FWHM). Due to the use of the LED chip, the primary light is particularly narrow-band. The corresponding primary spectrum may, for example, have a FWHM between 5 nm and 20 nm, such as about 15 nm. The spectral width of the secondary spectrum, particularly the FWHM, is preferably greater than 15 nm, particularly greater than 20 nm, and particularly greater than 30 nm. A particularly suitable range for the spectral width of the corresponding secondary spectrum, particularly the FWHM, is between 15 nm and 120 nm.

[0012] The conversion element specifically includes at least one light conversion material. In order to achieve different secondary spectra, the conversion elements of the corresponding LED units are preferably different, and in particular, the at least one light conversion material contained therein is different.

[0013] A conversion element, particularly a light-converting material contained therein, absorbs primary light and emits secondary light. Suitable conversion elements especially possess a light-converting material that exhibits luminescent properties, particularly photoluminescence, such as fluorescence or phosphorescence. Such materials are also called phosphors. A suitable light-converting material can be selected depending on the desired secondary spectrum.

[0014] Exemplary suitable phosphors include:

[0015] CaAlSiN3:Eu 2+ ,

[0016] (Sr,Ca)AlSiN3:Eu 2+ ,

[0017] Lu2O3:Eu 3+ ,

[0018] (Sr 2-x La x (Ce) 1-x Eu x O4、

[0019] Sr2Ce 1-x Eu x O4、

[0020] Sr 2-x Eu x CeO4,

[0021] SrTiO3:Pr 3+ Ga 3+ ,

[0022] Sr2Si5N8:Eu 2+ ,

[0023] CaSc2O4:Ce 3+ ,

[0024] CaSc2O4:Ce 3+ ,

[0025] Y3(Al,Ga)5O 12 :Ce 3+ ,

[0026] Lu3Al5O 12 :Ce 3+ ,

[0027] YAG:Ce 3+ ,

[0028] La3Si6N 11 :Ce 3+ and / or

[0029] (La,Y)3Si6N 11 :Ce 3+ .

[0030] Particularly suitable conversion elements include light-converting materials in the form of so-called quantum dots, such as cadmium-containing or cadmium-free quantum dots. Exemplary suitable materials for quantum dots are CdSe / ZnS, InP / ZnS, ZnSe / ZnS, and / or perovskites, particularly CsPbX3, where X is selected from the group consisting of Cl, Br, and / or I. Quantum dots are nanoparticles that have different emission spectra depending on their diameter and / or raw materials. The diameter can be, for example, between 1 nm and 20 nm, particularly between 1 nm and 12 nm, especially for CdSe-based quantum dots. Depending on the size and / or raw materials, the emission spectrum, particularly the peak position and / or spectral width, can thus be easily and effectively tuned. By appropriately mixing quantum dots of different diameters, the spectral width of the achieved secondary spectrum can be specifically tuned.

[0031] The light-emitting device has at least two LED units. The light-emitting device may have more than two LED units, particularly three, four, five or more LED units.

[0032] An LED unit has at least one LED chip to generate primary light. An LED unit may also have more than one LED chip. Different LED chips in an LED unit can generate primary light with the same primary spectrum or primary light with different primary spectra. The generation of different primary spectra can, for example, be used to excite different light conversion materials of corresponding conversion elements.

[0033] The secondary spectra of the different LED units in the at least two LED units are different. The secondary spectra of the different LED units may, in particular, have different peak wavelengths and / or different center wavelengths. The secondary spectra may, in particular, cover different ranges of the emission spectrum. The different secondary spectra may have overlapping spectral ranges. It is also feasible for the different secondary spectra to have near or equal peak wavelengths and / or center wavelengths. The different secondary spectra may, in particular, have the same color valence. Where appropriate, the secondary spectra may differ in their respective spectral widths. In this way, it is feasible to cover spectral ranges of different widths using corresponding secondary spectra.

[0034] The device according to claim 2 is particularly advantageous in terms of achievable color mixing. Different chromaticity values ​​of the secondary spectrum of the LED unit allow for the mixing of corresponding colors. Different chromaticity values ​​are specifically understood as corresponding secondary spectra that correspond to perceptually different colors for the observer, particularly different primary colors. Different chromaticity values ​​can be caused by different spectral curves. In particular, the corresponding secondary spectra can have different peak wavelengths and / or center wavelengths.

[0035] The device according to claim 3 enables particularly flexible mixing of secondary spectra. Specifically, it enables arbitrary color mixing of different chromaticities of the corresponding secondary spectra. Independent control of the respective LED units can be achieved, for example, by means of externally controlled power supplies for each connection of the LED units, particularly the LED chips. Preferably, the device, particularly the LED package, has an integrated circuit (IC) for controlling the respective LED units.

[0036] The apparatus according to claim 4 enables particularly precise determination of the emission spectrum, and particularly enables particularly uniform light color. This reliably avoids false colors in the emission spectrum caused by unconverted primary light.

[0037] The apparatus according to claim 5 is particularly advantageous and flexible. By means of at least three LED units covering the basic colors of the color system, colors of the corresponding color system can be produced with high quality. In particular, it is feasible to produce white light with high quality. Particularly preferably, the at least three LED units are independently controllable, thereby allowing the produced colors to be flexibly adjusted within the color space of the corresponding color system.

[0038] The resulting color system produces colors and / or white light with uniform mixing. This improves the characteristic quantities of the color system, particularly the correlated color temperature (CCT) and / or color rendering index (CRI).

[0039] The primary colors each covered by the secondary spectrum can be the primary colors of any color system. For example, this could be the primary colors of the RGB color system: red, green, and blue. It is also possible to reproduce the primary colors of other color systems using the secondary spectrum. For example, the CMY color system, with its primary colors cyan, magenta, and yellow, could be used. Depending on the dimensions of the color space allocated to the color system, three or more LED units can be configured.

[0040] Alternatively, at least six LED units can be configured to cover the basic colors of at least two color systems. This allows for coverage of either the primary or secondary color systems, further improving color rendering quality. For example, LED units covering the basic colors of both the RGB and CMY color systems could be present.

[0041] The apparatus according to claim 6 enables particularly precise determination of the emission spectrum, and in particular, enables the determination of the color of the light to be emitted. Specifically, the primary spectrum is entirely within the spectral range of the corresponding secondary spectrum. The LED chip of the LED unit is selectable depending on the corresponding color system. The LED chip can be, for example, an RGB LED.

[0042] The device according to claim 7 is characterized by particularly good color rendering. The color rendering index can be determined, for example, according to CIE standard system 13.3 (1995). The achievable color rendering index can depend particularly on the corresponding spectral width of the secondary spectrum of the LED unit.

[0043] The improved color rendering index is particularly noticeable compared to using conventional RGB LEDs. Conventional RGB LEDs have a color rendering index below 70 due to the narrow-band spectrum of the corresponding LED chips. Specifically, compared to the emission characteristics of LED chips using the corresponding basic colors of a color system but without corresponding conversion elements, the color rendering index of the emission spectrum of this device is improved by at least 5%, particularly by at least 10%, and especially by at least 20%.

[0044] Alternatively or additionally, the emission spectrum of the device preferably has a correlated color temperature lower than that of RGB LEDs with high color rendering indexes, particularly those corresponding to high color rendering indices. In RGB LEDs, color temperature and high color rendering index cannot typically be adjusted simultaneously. If a high color rendering index is to be achieved using RGB LEDs, typically only cool light of 7,000K or higher can be achieved.

[0045] The emission spectrum of this device can specifically have a correlated color temperature between 2,700K and 6,500K. This correlated color temperature can specifically depend on the spectral width of the corresponding secondary spectrum. Therefore, it is feasible to simply adjust the correlated color temperature. In particular, it is feasible to produce neutral white light or warm white light.

[0046] The apparatus according to claim 8 has particularly good color rendering properties, especially particularly good white light quality. The spectral width can be, in particular, the full width at half maximum (FWHM) of the secondary spectrum. By adjusting the spectral width, the desired correlated color temperature and / or the desired color rendering index can be significantly affected. A higher spectral width results in more uniform color mixing, especially in the production of white light. However, excessively high spectral widths lead to the superposition of corresponding secondary spectra, making it difficult to produce a single color under controlled conditions. A spectral width range of the secondary spectrum between 15 nm and 120 nm, particularly between 20 nm and 120 nm, has proven particularly suitable. For white light production, a spectral width of the secondary spectrum between 60 nm and 120 nm is particularly advantageous. For colored light production, a spectral width of the secondary spectrum between 20 nm and 60 nm is particularly advantageous.

[0047] The device according to claim 9 has proven particularly advantageous. The use of quantum dots as the light conversion material is particularly suitable for the tunability of the spectral width of the secondary spectrum. By using quantum dots of different diameters, the spectral width of the corresponding secondary spectrum can be flexibly and precisely adjusted to suit the respective application. For example, different groups of quantum dots with corresponding average diameters can be used, wherein the average diameters of these different groups of quantum dots are particularly different. Their respective contributions to light conversion can be particularly tunable by the corresponding proportion of the quantum dot groups in the conversion element. For example, quantum dots emitting different colors of light can be combined in the conversion element.

[0048] Preferably, the conversion element of the multiple LED units, especially all LED units, has quantum dots with different diameters.

[0049] The apparatus according to claim 10 enables particularly flexible generation and / or mixing of different secondary spectra. Different primary spectra of the LED chips in an LED unit can be selected, for example, such that different light-converting materials of the corresponding conversion elements are excited by these primary spectra. This light conversion is particularly efficient. For example, quantum dots of different diameters contained in the conversion elements can be excited by means of the corresponding primary spectra. Preferably, two or more LED units, particularly all LED units, can each have multiple LED chips with different primary spectra.

[0050] The apparatus according to claim 11 enables particularly flexible and precise adjustment of the mixing of different secondary spectra. Crosstalk is avoided by the corresponding shielding of the LED units. Excitation of the conversion elements of other LED units by the primary and / or secondary light of one LED unit is reliably prevented. It is particularly feasible, for example, to generate emitted light using individual LED units within the LED unit through corresponding individual control.

[0051] The device according to claim 12 is particularly effective in preventing crosstalk between different LED units. The arrangement of the LED units in the corresponding recesses or cavities of the substrate achieves effective shielding without the need for other structural measures, particularly without separate shielding elements. Furthermore, the LED units are also mechanically protected within the recesses of the substrate. The device is robust and durable.

[0052] The device according to claim 13 is robust and durable, and has a simple structure. Since the conversion element itself is a package of the corresponding LED chip, a separate package is not required. The LED chip is protected within the package. Furthermore, the package prevents the primary light from the corresponding LED chip from bypassing the conversion element and escaping outwards, thus avoiding interference with the desired color mixing.

[0053] Particularly preferably, at least one conversion element can be formed into a package of the corresponding LED chip in a corresponding recess in the substrate. Thus, the LED chip and the package are securely embedded in the recess.

[0054] The apparatus according to claim 14 enables the conversion element to be arranged at the respective LED chip in a particularly space-saving manner. Preferably, the entire exposed surface of the LED chip is coated with the conversion element. This coating prevents the primary light from the LED chip from bypassing the conversion element and escaping.

[0055] Another object of the present invention is to improve a lamp.

[0056] This objective is achieved by the luminaire according to claim 15. The luminaire has at least one light-emitting device, as described above. The luminaire may have at least one or more corresponding LED packages. The advantages and optional features of this luminaire correspond to the advantages and optional features of the aforementioned device. Attached Figure Description

[0057] Further features, advantages, and details of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings. Wherein:

[0058] Figure 1 A first embodiment of a light-emitting device with three LED units in the form of an LED package is schematically shown;

[0059] Figure 2A An exemplary emission spectrum of a known RGB LED is shown;

[0060] Figure 2B Showing according to Figure 1 Exemplary emission spectrum of an LED package;

[0061] Figure 3A Showing according to Figure 1 An example color temperature of the LED cell in the LED package, which depends on the spectral width of the secondary spectrum;

[0062] Figure 3B Showing according to Figure 1 An example color rendering index of the LED unit in the LED package, which depends on the spectral width;

[0063] Figure 3C Showing according to Figure 3B The percentage increase in color rendering index relative to known RGB LEDs;

[0064] Figure 4 Another embodiment of a light-emitting device employing an LED package is schematically shown;

[0065] Figure 5 Another embodiment of a light-emitting device employing an LED package is schematically shown;

[0066] Figures 6A to 6C The diagram schematically shows quantum dots of different diameters and their mixed emission spectra.

[0067] The corresponding parts, components, and spectra and / or other quantities are in Figures 1 to 5 The same reference numerals are used in the accompanying drawings. The details of the embodiments described below in more detail may themselves constitute an invention or part of the subject matter of the invention. Detailed Implementation

[0068] exist Figure 1 The image schematically shows a first embodiment of a light-emitting device 1 using an LED package. The LED package 1 has a substrate 2 on which a plurality of LED units L are arranged. i The subscripts i = 1, 2, ... refer here and below to different LED units and associated (sub)elements, spectra, and characteristic quantities. In the illustrated embodiment, three LED units L are shown. i That is, L1, L2 and L3 and their respective (sub)elements, spectra and characteristic variables (subscript i = 1, 2, 3).

[0069] LED unit L i It has the ability to generate primary light P i LED chip Ci LED unit L i It has the ability to convert the corresponding primary light P i Converted to secondary light S i conversion element K i .

[0070] Primary light P i The primary spectrum is narrow-band. With the help of a corresponding conversion element K... i The generated secondary light S i This results in a secondary spectrum with a wider spectral width than the primary spectrum. Therefore, the obtained secondary spectrum is superior to that obtained using an LED chip C. i The resulting primary spectrum is wider. The spectral width of the secondary spectrum can be specifically quantified as the full width at half maximum (FWHM). The FWHM of the secondary spectrum is particularly in the range between 15 nm and 120 nm.

[0071] The corresponding LED unit L i Secondary light S i The LEDs have different secondary spectra, each having a color valence corresponding to a primary color of the color system. In the illustrated embodiment, the color valence of the respective secondary spectra corresponds to the primary colors red, green, and blue of the RGB color system. LED unit L i Secondary light S i The superposition forms emitted light A, which has an emission spectrum corresponding to the superposition of the corresponding secondary spectrum.

[0072] With the help of integrated circuit 3, LED unit L i These can be controlled independently. This allows adjustment of the mixing of the secondary spectrum in emitted light A, thereby adjusting the resulting emission spectrum. This is achieved by using secondary light S, which corresponds to the primary color of the color system. i The mixing of these elements can produce emitted light of any color in the RGB color space, especially white light.

[0073] In the illustrated embodiment, the switching element K i Designed as the corresponding LED chip C i The package contains light conversion material. This is for generating secondary light S... i The corresponding, different secondary spectra, conversion element K iDifferent light-converting materials and / or different mixtures of light-converting materials are used. Suitable light-converting materials are, in particular, so-called quantum dots, which may or may not contain cadmium. Quantum dots are nanoparticles that absorb light and emit it at different wavelengths. The emitted wavelength depends on the diameter of the corresponding quantum dot and / or the raw material. Therefore, by appropriately selecting quantum dots of different diameters and / or different materials, the secondary spectrum, especially its spectral width, can be tuned in a targeted and simple manner. The appropriate diameter can depend on the material of the quantum dot. For example, diameters from 1 nm to 20 nm can be selected, particularly for CdSe-based quantum dots.

[0074] Corresponding LED chip C i Primary light P i The primary spectrum is not very important. For different LED units L i Primary light P can be selected in the same or different ways. i The advantage is that you can select the corresponding LED chip C. i Its primary light P i By the corresponding conversion element K i The light conversion material absorbs light particularly well.

[0075] The following text details the LED chip C. i and corresponding conversion element K i A concrete, purely exemplary example of the combination:

[0076] The LED chip C1 of LED element L1 has a primary spectrum with a peak value of approximately 385 nm for the produced primary light P1. The conversion element K1 has a light-converting material in the form of quantum dots, which exhibits good absorption below 450 nm, particularly effective absorption at 385 nm, and its secondary light S1 has a secondary spectrum with a peak value of approximately 450 nm. The full width at half maximum (FWHM) is approximately 60 nm. The resulting color valence corresponds to blue light.

[0077] The LED chip C2 of LED element L2 has a primary spectrum with a peak value of approximately 450 nm for the produced primary light P2. The conversion element K2 is a light-converting material in the form of quantum dots, exhibiting good absorption below 500 nm, particularly effective absorption at 450 nm, and its secondary light S2 has a secondary spectrum with a peak value of approximately 515 nm. The full width at half maximum (FWHM) is approximately 60 nm. The resulting color valence corresponds to green light.

[0078] The LED chip C3 of LED element L3 has a primary spectrum with a peak value of approximately 450 nm for the produced primary light P3. The conversion element K3 is a light-converting material in the form of quantum dots, exhibiting good absorption below 650 nm, particularly effective absorption at 450 nm, and its secondary light S3 has a secondary spectrum with a peak value of approximately 640 nm. The full width at half maximum (FWHM) is approximately 60 nm. The resulting color valence corresponds to red light.

[0079] The following text details the LED chip C. i and corresponding conversion element K i Another purely exemplary example of a combination. LED chip C i These are RGB LEDs, each possessing a primary spectrum within the red, green, or blue color gamut. The conversion element K... i A mixture of quantum dots, each with different materials and / or different diameters, wherein these quantum dots, particularly their diameters, are chosen such that the secondary spectrum superimposed on the corresponding primary spectrum. Specifically, the primary spectrum is entirely within the spectral range of the corresponding secondary spectrum. This is achieved through a conversion element K. i This expands the spectral width without the false color caused by the unconverted portion of the primary light. Different quantum dots, especially those of different diameters, have different conversion elements K. i The mixing in the LED chip allows for the precise determination of the spectral width of the corresponding secondary spectrum, as will be described in more detail below. i and the corresponding conversion element K i A specific example of a purely exemplary combination is:

[0080] - The LED chip C1 of the LED component L1 has a red primary spectrum. The conversion element K1 is a mixture of different quantum dots that emit red and far-red light, respectively. The different quantum dots can be made of different materials and / or have different diameters. Exemplary diameters of quantum dots, particularly CdSe-based quantum dots, can be 6 nm (red light) and 12 nm (far-red light).

[0081] - The LED chip C2 of the LED component L2 has a green primary spectrum. The conversion element K2 is a mixture of different quantum dots that emit green and orange light, respectively. The different quantum dots can be made of different materials and / or have different diameters. Exemplary diameters of quantum dots, particularly CdSe-based quantum dots, can be 3 nm (green light) and 5 nm (orange light).

[0082] - The LED chip C3 of the LED component L3 has a red primary spectrum. The conversion element K3 is a mixture of different quantum dots that emit blue and green light, respectively. The different quantum dots can be made of different materials and / or have different diameters. Exemplary diameters of quantum dots, particularly CdSe-based quantum dots, can be 2 nm (blue light) and 3 nm (green light).

[0083] refer to Figure 2A and Figure 2B The emission spectrum generated by the LED package 1 is explained in more detail. In the figure, the normalized intensity I as a function of wavelength λ (in nm) is plotted for different spectra.

[0084] exist Figure 2A The image shows the spectral intensity of a single LED in a known RGB LED package. The corresponding spectra of the LEDs are labeled with their respective colors: blue (B), green (G), and red (R). RGB LEDs have small full width at half maximum (FWHM). The total spectrum (dashed line) resulting from their superposition is white light; however, due to the small FWHM of each individual spectrum, this white light is not very uniform.

[0085] exist Figure 2B The image shows the corresponding LED unit L of LED package 1. i Corresponding secondary light S i The secondary spectrum. Through the corresponding conversion element K i Compared to using RGB LEDs, the full width at half maximum (FWHM) of the secondary spectrum is broadened. In the illustrated embodiment, the FWHM is 60 nm in each case. Therefore, the corresponding secondary light S i The emission spectrum of the superimposed emitted light A has a more uniform intensity across the visible light wavelength range (shown in the figure from 380 nm to 780 nm). This improves the characteristic properties of the emitted light, particularly the correlated color temperature and color rendering index.

[0086] refer to Figure 3A , 3B The improvement of the characteristic parameters of emitted light A is described in more detail in 3C.

[0087] The corresponding LED unit L is shown in the figure. i The figure shows various characteristic quantities of the secondary spectrum as a function of full width at half maximum (FWHM). Figure 3 shows the correlated color temperature (CCT) (in K) of the secondary spectrum as a function of FWHM (in nm). The cross symbol "x" in the figure represents the CCT of the total spectrum of the RGB LED, as shown for example in... Figure 2AAs shown in the diagram. In this case, the intensity ratios of individual LEDs R, G, and B are chosen such that the color rendering index of the RGB LED is optimized. The full width at half maximum (FWHM) of the RGB LED spectrum is typically about 15 nm. The solid line represents the CCT of the output light A of LED package 1. As the FWHM increases, the CCT decreases, while the ratio of LED R, G, B remains constant. RGB LEDs produce cool white light, while neutral white and / or warm white output light A can be produced in a simple manner through LED package 1.

[0088] exist Figure 3B The image shows the Color Rendering Index (CRI) as a function of the full width at half maximum (FWHM). The CRI of RGB LEDs is again marked with an "x" at the corresponding FWHM of approximately 15 nm. The solid line represents the CRI of the output light A of LED package 1, which depends on the FWHM of the corresponding secondary spectrum. Compared to RGB LEDs, the CRI is significantly improved. The CRI is above 70. The CRI is particularly improved for the spectral width of the secondary spectrum between 20 nm and 120 nm. In particular, a spectral width of 60 nm to 120 nm is advantageous for white light production. To produce colored light, a spectral width particularly between 20 nm and 60 nm can be selected.

[0089] Figure 3C The relative improvement in CRI compared to RGB LEDs is shown. The improvement is at least 5%. Depending on FWHM, the improvement can be 20% or more.

[0090] exist Figure 4 Another embodiment of the LED package 1a is schematically shown in the diagram. (See also...) Figure 1 The components described in the embodiments are marked with the same reference numerals and will not be explained in detail. Components that are functionally corresponding but structurally different are marked with corresponding supplementary reference numerals "a".

[0091] LED unit La i The conversion element Ka i Designed as LED chip C i The coating. LED unit La i The integrated circuit 3 is encapsulated in a common transparent package 4. Package 4 gives the LED package 1a high structural integrity and stability.

[0092] exist Figure 5Another embodiment of the LED package 1b is schematically shown. Elements already described with reference to the previous embodiments carry the same reference numerals and will not be explained in detail. Elements that are functionally corresponding but structurally designed differently carry corresponding reference numerals supplemented by "b".

[0093] LED unit Lb i is embedded in the corresponding recess 5 of the substrate 2b. For this purpose, the LED chip C i is arranged at the bottom of the corresponding recess 5. The corresponding light conversion element Kb i serves as a package for filling the recess 5. By being arranged in the recess 5, the LED units Lb i shield each other, so that neither the primary radiation P i nor the secondary radiation S i directly enters from one of the LED units Lb i into another. Thereby, crosstalk is avoided. By correspondingly controlling the LED units Lb i , corresponding colors can be generated independently of each other without color mixing due to inadvertently exciting the light conversion elements Kb i of other LED units Lb i . The color rendering is particularly precise.

[0094] The conversion element K i of the LED unit L i can have a mixture of quantum dots with different diameters. The effect of the mixture of quantum dots with different diameters is elaborated in Figures 6A to 6C in more detail.

[0095] In Figure 6A the emission spectra of quantum dots with corresponding diameters D1 to D4 are schematically shown. Here, the intensity I is plotted as a function of the wavelength λ. The following applies to diameters D1 to D4: D1 < D2 < D3 < D4. It can be seen from Figure 6A that as the diameter increases, the emission spectra of the quantum dots shift towards longer wavelengths λ. It has been recognized that a mixture of quantum dots with different diameters can be used to adjust the spectral width of the conversion element K.

[0096] In Figure 6B for example, the emission spectrum (dashed line) of a conversion element K is shown, which has a mixture of quantum dots with different diameters D1 and D2.

[0097] In Figure 6C the emission spectrum (dashed line) of a conversion element K is示例性 shown, which has a mixture of quantum dots with different diameters D1, D2 and D3.

[0098] Depending on the mixing of quantum dots, the spectral width of the conversion element K can be precisely and flexibly adjusted, and thus the secondary spectrum of the corresponding LED unit L can be adjusted.

[0099] exist Figure 6B and 6C The conversion element K shown is, for example, a mixture of quantum dots with a mixing ratio of 1:1. It is also possible to use other mixing ratios of corresponding quantum dots with different diameters to more precisely adjust the spectral width, particularly the secondary spectrum, of the corresponding conversion element K to suit the specific application.

Claims

1. A light emitting device, in particular an LED package, having at least two LED units (L i ; La i ; Lb i ), each having: - at least one LED chip (C i ) for generating primary light (P i ) having a primary spectrum; and - a conversion element (K i ; Ka i ; Kb i ) for converting the primary light (P i ) into secondary light (S i ) having a secondary light spectrum with a greater spectral width than the primary light spectrum, wherein the secondary light spectrum of different LED units of the at least two LED units (L i ; La i ; Lb i ) is different.

2. The light emitting device according to claim 1, characterized in that The secondary light spectrum of the different LED units (L i ; La i ; Lb i ) have different color values.

3. The light emitting device according to any of the preceding claims, characterized in that The at least two LED units (L i ; La i ; Lb i ) are independently controllable from each other for adjusting the mixing of the secondary light spectrum of the at least two LED units (L i ; La i ; Lb i ), in particular by means of an integrated circuit (3) of the light emitting device (1; la; lb).

4. The light emitting device according to any of the preceding claims, characterized in that the at least two LED units (L i ) are configured to emit light of different colors. i ; Lb i ) are configured to emit light of different colors. i ) of the respective LED chips (C i ) of the at least two LED units (L i ) are selected such that the primary light spectrum is completely within the spectral range of the respective secondary light spectrum.

5. The light emitting device according to any of the preceding claims, characterized in that at least three LED units (L i ; La i ; Lb i ) whose secondary spectra have a color value corresponding to a basic color of the color system.

6. The light emitting device according to claim 5, characterized in that The LED chips (C i ) of the respective LED unit (L i ) emit a primary light (P i ) corresponding to the basic color of the respective color system. i ; Lb i ) of the respective LED unit (L i ) emit a primary light (P i ) corresponding to the basic color of the respective color system.

7. The light emitting device according to claim 5 or 6, characterized in that The color rendering index (CRI) of the emission spectrum obtained by superimposing the secondary spectra exceeds 70, in particular exceeds 75, in particular exceeds 80.

8. The light emitting device according to any of the preceding claims, characterized in that The spectral width of the secondary spectra is each between 15 nm and 120 nm.

9. The light emitting device according to any of the preceding claims, characterized in that The conversion element (K i ; La i ; Lb i ) of at least one LED unit (L i ; Ka i ; Kb i ) has quantum dots of different diameters.

10. The light emitting device according to any of the preceding claims, characterized in that At least one LED unit (L i ;La i ;Lb i It has multiple LED chips (C) i Their primary spectra are all different.

11. The light emitting device according to any of the preceding claims, characterized in that The LED units (L i ; La i ; Lb i ) shield each other in such a way that light of one LED unit (L i ; La i ; Lb i ) cannot directly impinge on the conversion medium (K i ; Ka i ; Kb i ) of another LED unit (L i ; La i ; Lb i ).

12. The light emitting device according to claim 11, characterized in that The LED units (L i ; La i ; Lb i ) are arranged in respective recesses (5) of the substrate (2b).

13. The light emitting device according to any of the preceding claims, characterized in that At least one of the conversion elements (K i ,Kb i ) constitutes a package for the respective LED chip (C i ) comprising a light conversion material.

14. The light emitting device according to any of the preceding claims, characterized in that At least one of the conversion elements (Ka i ) is applied as a coating to the respective LED chip (C i ).

15. A luminaire having at least one light emitting device (1; la; lb) according to any of the preceding claims.

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