Light source with light-emitting component

FIELD: devices built around diodes emitting blue and/or ultraviolet light.

SUBSTANCE: proposed light source emitting light in ultraviolet or blue light region (from 370 to 490 nm) and capable of producing high-efficiency white light affording control of luminance temperature within comprehensive range has light-emitting component that emits light in first spectral region and phosphor of group of optosilicate alkali-earth metals and that absorbs part of source light and emits light in other spectral region. Novelty is that phosphor used for the purpose is, essentially, europium activated bivalent optosilicate of alkali-earth metal of following composition: (2-x-y)SrO · x(Ba_u, Ca_v)O · (1-a-b-c-d)SiO₂ ·aP₂O₅bAl₂O₃cB₂O₃dGeO₂ : yEu²⁺ and/or (2-x-y)BaO · x(Sr_u, Ca_v)O · (1-a-b-c-d)SiO₂ ·aP₂O₅bAl₂O₃cB₂O₃dGeO₂ : yEu²⁺.

EFFECT: enhanced efficiency, enlarged luminance temperature control range.

14 cl, 10 dwg

The technical field

This invention relates to a light source to generate white light containing a light-emitting diode (LED) for emitting blue and/or ultraviolet radiation, at least one phosphor, which emits some of the blue and/or ultraviolet radiation, and even radiation in another spectral region.

Prior art

Inorganic LEDs are characterized, among other things, long service life, small footprint, insensitivity to vibration and radiation in a narrow band of the spectrum.

The LEDs using the inherent radiation of semiconductor material is almost impossible, although it is possible, but it is very inefficient to implement numerous color radiation in a wide range of radiation.

In WO 00/33390 described light-emitting device containing a light-emitting diode, emitting extremely blue light, or a laser diode, which interacts with a mixture of phosphors.

At the same time to create white light led emitting in the spectral range from 420 to 470 nm, is combined with a mixture of phosphors consisting of at least two phosphors. For this it is necessary that two phosphor radiated with different spectra. Used a mixture of phosphors always contains one red component is a green component. In this case, due to the mixing of these colors with a blue radiation emitted by the led, white light occurs.

The white light sources for General lighting have generally increased requirements to the quality of color reproduction lighting. Secondly, customers, primarily in Europe and North America, prefer warmer color light with color temperatures ranging from 2700 to 5000 K.

From WO 00/33389 also known application of Ba₂SiO₄:Eu²⁺as the phosphor, among others, to convert the light emitted by the blue LEDs. However, the maximum radiation of the phosphor Ba₂SiO₄:Eu²⁺approximately 505 nm, so that by using this combination cannot be reliably create white light.

In the work SHM of Porta (S.H.M. Poort) and others: "Optical properties of Eu²⁺-activated orthosilicates and orthophospates" (“Optical properties of orthosilicates and orthophosphate activated UOM²⁺”, journal of Alloys and Compounds”, 260 (1997), pp. 93-97) we investigate the properties of Ba₂SIO, SIS₄activated Unit, and phosphates such as Quero₄and KSrPO₄. It also States that the emission of Ba₂SiO₄approximately 505 nm.

The invention

The objective of the present invention consists, therefore, is to produce an improved source for the light, where as the radiation source applies light emitting diode (LED), and the radiation source can emit in the ultraviolet region or in the region of blue (from 370 to 490 nm), and which is able to create white light with high efficiency by using improved phosphor, thus allowing the use of this source of white light for lighting purposes.

Simultaneously, the aim is to avoid the disadvantages known from prior art. In this case, furthermore, the application of one or more phosphors is necessary to provide the possibility of adjustment in a wide range of color temperatures to meet the diverse needs of users and, in particular, to adjust the color in those places that are within the tolerance ellipses established for General lighting International Commission on illumination (CIE).

This problem is solved by creating a light source mentioned above, in which

the phosphor is a activated by divalent europium of orthosilicate alkaline-earth metal of one of the following compounds or a mixture of these compounds:

a) (2-x-y)SrO· x(BA_u, CA_vO· (1-a-b-c-d)SiO₂·aP₂O₅bl 2About₃St₂About₃dG₂: EIM²⁺

where

0≤ x≤ 1,6 0,005<y<0.5 x+y≤ 1,6

0≤ a,b,c,d<0.5 u+v=1;

b) (2-x-y)BaO· x(Sr_uCa_vO· (1-a-b-c-d)SiO₂·ar₂About₅bAl₂O₃St₂About₃dGe₂:y Eu²⁺

where

of 0.01<x<1,6 0,005<<0,5

0≤ a,b,C,d<0.5 u+v=1 x· u>0,4;

radiation of the phosphor is emitted yellow-green, yellow or orange region of the spectrum;

- at the same time by selecting options in these areas, you can adjust the color temperature and color index is created of white light.

In a preferred embodiment, the at least one of the values a, b, c and d are larger than 0.01. In addition, the previously mentioned the phosphor fraction of silicon may be replaced by gallium.

It was established that white light with good colour reproduction and a significant light output can be implemented by combining a blue led with phosphor selected from the above group activated by divalent europium of orthosilicates alkaline-earth metals. In contrast to the phosphors, which are based on orthosilicate pure barium and emit green with a bluish tinge to light, it is with mixed crystals of orthosilicate barium-strontium can create fluorescent light in the area from yellow-green, yellow to orange-yellow color, and the inclusion of calcium in the crystal lattice of orthosilicate - even a very orange color, and mixing the captured light of the blue led and emits fluorescent light of a selected phosphor is possible to generate white light with good colour reproduction and high efficiency. The color shift of the radiation by the substitution of barium (BA) strontium (Sr) orthosilicate for excitation of hard ultraviolet radiation (excitation at 254 nm) has so far been known only from the work of Porta etc. But the fact that this effect is unexpectedly pronounced upon irradiation with blue light in the range 440-475 nm, still not documented. Mixed crystals of orthosilicate Ba-Sr-Ca and their strong emissivity at excitation wavelength ultraviolet radiation or blue light still were completely unknown.

The selected phosphor can also be used in mixtures with other phosphors of this group and/or with additional luminous paints that do not belong to this group. To the above-mentioned fluorescent dyes include, for example, emitting blue light aluminate alkaline-earth metal activated by divalent europium and/or manganese, and emitting red light, the phosphor from the group of Y (V, P, Si)₄: Eu, Bi, Y₂O₂S: Eu, Bi or activated by europium and manganese disilicate alkaline-earth magnesium: EU²⁺, Mn²⁺with the formula

Me_(3-x-y)MgSi₂About₈:xEu, yMn,

where

of 0.005<x<0,5

of 0.005<<0,5

and Me = BA and/or Sr and/or CA.

As shown in the following examples of the invention, the proportion of Sr in the phosphors mixed crystals according to this invention, should not be too small so as to enable the generation of white light.

Further, it was also found that the additional inclusion of P₂O₅, Al₂About₃and/or In₂About₃in the crystal lattice of orthosilicate, as well as the replacement of part of the silicon germanium, therefore, have a significant impact on the emission spectrum of the corresponding phosphor, so that this range can be modified favorably on for the purposes of the application. While ions are smaller than Si (IV)contribute to the shift of the maximum radiation in the longwave region, while larger ions displace the center of radiation at shorter wavelengths. In addition, it was found that the crystallinity, emissivity and especially for the stability of the phosphors according to this invention may preferably further include the crystal lattice of the phosphor small amounts of monovalent ions, as, for example, halides and/or alkali metals.

According to another preferred variant implementation of the invention, the light source has at least two different phosphor, and at least one of them is glowing-based paint orthosilicate alkaline-earth metal. In this way it is possible to accurately set the shade of white that is required for the corresponding application, and, in particular, it is possible to obtain values of Ra is greater than 80. Another preferred variant of the invention consists in the combination of LEDs emitting in the ultraviolet region of the spectrum, for example, in the range from 370 to 390 nm, at least three luminous paints, of which at least one is a luminous paint on the basis of orthosilicate alkaline-earth metal according to this invention. As an additional luminous paints in the respective mixtures of fluorescent paints can be used for emitting blue light of the alkali earth metal aluminate activated by europium and/or manganese and/or emitting red light, the phosphor from the group of Y (V, P, Si)₄: Eu, Bi, Y₂O₂S: Eu, Bi or activated by europium and manganese disilicate alkaline-earth magnesium.

There are several options mechanical implementation of the light source soglasovannom invention. According to one variant embodiment of the invention is provided for mounting one or more led crystal on the circuit Board inside of the reflector and the dispersion of the phosphor in the light disk located above the reflector. Alternatively, you can mount one or more led crystal on the circuit Board inside of the reflector and cause the phosphor to the reflector.

It is preferable to fill led crystal clear casting mass, having a domed shape. This casting mass forms, on the one hand, mechanical protection; on the other hand, it also improves the optical properties (increasing the light output of the led crystal).

The phosphor may be dispersed in the casting mass, which connects the world of led crystals on a printed circuit Board and a polymer lens, if possible, without gas inclusions, and polymeric lens and casting weight have refractive indices that differ by no more than 0.1. This casting mass can directly turn on the led chip, but it can also pour the clear casting mass (hence, in this case, there is a transparent casting weight and casting weight with phosphor). Due to the similar refractive indices at the interfaces almost no losses and the recording.

Preferably, the polymer lens has a hollow spherical or ellipsoidal shape, filled with the filling mass so that the led array is fixed at a slight distance from the polymer lens. Thus it is possible to reduce the height of the mechanical Assembly. In order to achieve uniform distribution of the phosphor, it is advisable phosphor preferably suspended in an inorganic matrix. When using at least two phosphors, it is advisable to separately suspended in the matrix, at least two luminescent material, arranged one behind the other in the direction of light propagation. This makes it possible to reduce the concentration of phosphors compared to the homogeneous dispersion of the different phosphors.

Below are the important stages in the preparation of phosphors in a preferred embodiment of the invention.

For the manufacture of phosphors based orthosilicate alkaline-earth metals according to the selected composition is thoroughly mixed in stoichiometric quantities initial substance is a carbonate of alkaline-earth metal, silicon dioxide, and oxides of europium, which during solid-phase reaction, conventional for the manufacture of fluorescent paints, in a reducing atmosphere at temperatures in the range from 1100° 1400° To make the camping in the desired phosphor. However, crystallinity is advantageous to add to the reaction mixture a small proportion, preferably less than 0.2 mol, ammonium chloride or other halides. In the claimed invention can also replace part of silicon germanium, boron, aluminum, phosphorus, by adding compounds of these elements in appropriate amounts, which can be subjected to thermal decomposition in the oxides. In this way it is possible to achieve embedding small amounts of ions of alkaline-earth metals in the corresponding lattice.

The obtained phosphors based orthosilicate according to this invention emit at wavelengths of from about 510 nm to 600 nm and has a peak width of 110 mm

Thanks to the respective parameters of the reaction and due to certain additives, for example, monovalent ions halide and/or alkaline-earth metals, particle size of the phosphors according to this invention can be optimally adapted to the requirements of the respective application without using causing damage to the processes of mechanical grinding. This way you can install all narrow and broadband granulometric composition with an average grain size d₅₀from about 2 microns to 20 microns.

Brief description of drawings

Further advantages of the image is the shadow explained below by means of embodiments of the invention and drawings.

In Fig. 1-6 shows the spectra (relative intensity I according to the wavelength) different led light sources according to this invention, and Fig. 7-10 shows the different embodiments of led light sources according to this invention.

The best ways of carrying out the invention

In Fig. 1 shows the emission spectrum of a white led with a color temperature of 2700 K, which arose as a result of combination of a blue led emitting in a first spectral range with a Central wavelength of 464 nm, and the phosphor according to this invention, having the composition of (Sr_1,4Ca_{for 0.6}SIO, SIS₄:Eu²⁺), emitting in the second spectral region with a maximum 596 nm.

Other examples of combinations of LEDs, emitting at a wavelength of 464 nm, with a single phosphor-based orthosilicate according to this invention is shown in Fig. 2 and 3. If color conversion is applied to the phosphor emitting yellow light, a composition of Sr_1,90Ba_0,08Ca₀,₀₂SiO₄: Eu²⁺you can set the color of white light with a color temperature of 4100 K, while when applying the phosphor with the composition of Sr_1,84Ba_0,16SIO, SIS₄:Eu²⁺it is possible to make a white light source with a color temperature of 6500 K.

A typical range for the combination of the led is and 464 nm with two phosphors based orthosilicate according to this invention is shown in Fig. 4. Applied luminous paints are compositions of Sr_1,4Ca_{for 0.6}SIO, SIS₄:Eu²⁺and Sr_1,00Ba_1,00SIO, SIS₄: Eu²⁺. For a particular spectrum, shown in Fig. 4, the obtained color temperature 5088 It and the color reproduction index Ra=82. Of course, depending on the selected quantitative ratios of the phosphors can implement any color temperature in the range from about 5500 K To 7500 K, and the big advantage of such mixtures of the two phosphors based orthosilicate alkaline-earth metals according to this invention is that it is possible simultaneously to obtain the values of Ra more than 80.

This is the example that is illustrated in Fig. 5. Presents range refers to the combination of the led at 464 nm with a mixture of two phosphors Sr_1,6Ca_{for 0.4}Si_0,98Ga_0,02°₄:Eu²⁺and Sr_1,10Ba_0,90SIO, SIS₄: Eu²⁺and when the color temperature of 5000 K ensures that the value of Ra=82.

If the element emitting radiation, is applied UV led emitting in the first spectral region with a maximum 370-390 nm, thanks to the combination of such a led with a mixture of fluorescent paints, which contains phosphors, see Fig. 4, according to this invention, and along with it a certain proportion of luminous paint on the basis of alumina is and barium-magnesium: Eu, MP, radiant blue-green color, you can implement the Ra-value greater than 90. In Fig. 6 shows the emission spectrum of the corresponding source of white light with a color temperature of 6500 K is Ra=91.

Other examples can be taken from the list below, which, along with the wavelength of the radiation used inorganic LEDs and the corresponding composition of the phosphors according to this invention, indicated the resulting color temperature and Ra values, and chromaticity coordinates of light sources:

T=2778 (464 nm + Sr_1,4Ca_{for 0.6}SiO₄: Eu²⁺); x=0,4619, y=0,4247, Ra=72;

T=2950 K (464 nm + Sr_1,4Ca_{for 0.6}SiO₄: Eu²⁺); x=0,4380, y=0,4004, Ra=73;

T=3497 K (464 nm + Sr_1,6Ba_{for 0.4}SiO₄: Eu²⁺); x=0,4086, y=0,3996, Ra=74;

T=4183 (464 nm + Sr_1,9Ba_0,08Ca_0,02SIO, SIS₄: Eu²⁺); x=0,3762, y=0,3873; Ra=75;

T=6624 (464 nm + Sr_1,9Ba_0,02Ca_0,08SIO, SIS₄: Eu²⁺); x=0,3101, y=0,3306; Ra=76;

T=6385 (464 nm + Sr_1,6Ca_{for 0.4}SIO, SIS₄: S²⁺+ Sr_{for 0.4}Ba_1,6SIO, SIS₄: Eu²⁺); x=0,3135, y=0,3397, Ra=82;

T=4216 (464 nm + Sr_1,9Ba_0,08Ca_0,02SIO, SIS₄: Eu²⁺); x=0,3710, y=0,3696; Ra=82;

T=3954 (464 nm + Sr_1,6Ba_{for 0.4}SIO, SIS₄: Eu²⁺+ Sr_{for 0.4}Ba_1,6SIO, SIS₄: S²⁺+ YV₄: Eu²⁺; x=0,3756, y=0,3816, Ra=84;

T=6489 (UV led + Sr_1,6Ca_{for 0.4}SIO, SIS₄: Eu²⁺+ Sr for 0.4Ba_1,6SIO, SIS₄: Eu²⁺+ aluminate, barium-magnesium: EU²⁺); x=0,3115, y=0,3390, Ra=86;

T=5097 (464 nm + Sr_1,6Ba_{for 0.4}(Si_0,98B_0,01) O₄: Eu²⁺+ Sr_{for 0.6}Ba_1,4SIO, SIS₄: Eu²⁺); x=0,3423, y=0,3485, Ra=82;

T=5084 (UV led + Sr_1,6Ca_{for 0.4}(Si_0,99B_0,01) SIO, SIS₄: Eu²⁺+ Sr_{for 0.6}Ba_1,4SIO, SIS₄: Eu²⁺+ aluminate strontium-magnesium: Eu²⁺); x=0,3430, y=0,3531, Ra=83;

T=3369 (464 nm + Sr_1,4Ca_{for 0.6}Si_{of 0.95}Ge_0,05°₄: Eu²⁺; x=0,4134, y=0,3959, Ra=74;

T=2787 (466 nm + Sr_1,4Ca_{for 0.6}Si_0,98P_0,02°₄: Eu²⁺); x=0,4630, y=0,4280, Ra=72;

T=2913 (464 nm + Sr_1,4Ca_{for 0.6}Si_0,98Al_0,02°₄: Eu²⁺); x=0,4425, y=0,4050, Ra=73;

T=4201

In a preferred embodiment of the invention the formation of color as follows:

On the circuit Board 2 are collected one or more led crystal 1 (see Fig. 7). Directly above the LEDs is placed a sealing means in the housing 3 in the form of a hemisphere or powelliphanta (on the one hand, to protect the led crystals and, on the other hand, to provide improved output light generated in the led). This sealing means in the housing 3, or may contain each chip individually, or can be a General form is for all crystals.

Mounted circuit Board 2 such is inserted into the reflector 4, or the reflector is superimposed over the led crystals 1.

The reflector 4 is mounted luminous disk 5. It serves, on the one hand, to protect the chip Assembly; on the other hand, in this light disc entered the phosphors 6. Blue light (or ultraviolet light), light passing through the disk 5, while passing the partially converted by the phosphor 6 in the second spectral region, so you get the depth of white. Losses due to effects of the waveguides, resulting in plane-parallel plates reduced owing to the properties of opacity and scattering disk. Further, the reflector 4 ensures that a light on the drive just pre-directional light, so the full effects of reflection immediately attenuated.

You can also apply the phosphor 6 on the reflector 4, as shown in Fig. 8. In this case, light washer is not needed.

Alternatively, this above each led crystal 1 (see Fig. 9) you can attach the reflector 4’ and pour it into the shape of a dome (the means of sealing in the housing 3’), and above each reflector 3’ or over the entire world to host luminous disk 5.

For the manufacture of light sources suitable instead of individual LEDs to apply the matrix St is todiode. In a preferred embodiment of the invention the formation of the color is performed on the matrix of LEDs 1’ (see Fig. 10), which led crystals 1 assembled on a printed circuit Board 2, as follows:

Matrix LEDs 1’ (see Fig. 10) is attached by means of the filling mass (3) (e.g., epoxy) to a transparent polymer lens 7, which consists of another material (for example, emission spectra obtained for pure (polymethyl methacrylate)). The polymeric materials of the lens 7 and the casting mass 3 are selected so that their refractive indices were close as possible, i.e. the coordinated phase. Casting weight 3 is located in the recess of the maximum spherical or ellipsoidal form a polymeric lens 7. The shape of the grooves is set as long as the casting mass 3 dispersed material for the conversion of color. Therefore, by means of giving form to ensure the creation of color, independent of the angle. Alternatively, this matrix can first pour the clear casting mass, and then glued to the plastic lens using a casting mass, which contains the material for the conversion of color.

For the manufacture of white LEDs with very good colour reproduction, which use at least two different phosphor, it is advisable dispergirovany the ü they are not together in the matrix, and is atomized and applied separately. This is especially true for combinations in which the final color of the light generated in the multistage process of forming the color. This means that the color of the long-wave radiation is generated in the process of radiation, which runs as follows: the absorption of radiation of the led, the first phosphor, the emission of the first phosphor, the radiation absorption of the first phosphor to the second phosphor and the emission of the second phosphor. Especially preferred for this kind of process to place different materials to each other in the direction of light propagation, since this makes it possible to reduce the concentration of materials in comparison with the homogeneous dispersion of various materials.

This invention is not limited to the described examples. Phosphors can also be entered in the polymer lens (or other optics). You can also place the phosphor directly on top of the led chip on the surface of the transparent molding mass. The phosphor can also be entered in a matrix together with the scattering particles. Through this prevents the deposition of particles in the matrix and provides uniform light output.

1. The source of light to create white light containing a light-emitting diode (LED) for IP is Askania blue and/or ultraviolet radiation, and at least one phosphor, which emits some of the blue and/or ultraviolet radiation, and even radiation in another spectral region, characterized in that the phosphor is a activated by divalent europium of orthosilicate alkaline-earth metal of one of the following compounds or a mixture of these compounds:

a) (2-x-y)SrO· x(BA_uCa_v)O (1-a-b-C-d)SiO₂·ar₂About₅bl₂O₃St₂About₃dG₂:yEu²⁺

where

0≤ x<1,6 0,005<y<0.5 x+y≤ 1,6

0≤ a, b, C, d<0.5 u+v=1;

b) (2-x-y)BaO· x(Sr_uCa_vO· (1-a-b-C-d)SiO₂·ar₂About₅bl₂O₃St₂About₃dG₂:yEu²⁺

where

of 0.01<x<1,6 of 0.005<x<0,5

0≤ a, b, C, d<0.5 u+v=1 x· u≥ 0,4;

the radiation of the phosphor is emitted yellow-green, yellow or orange region of the spectrum, while by selecting options in these areas, you can adjust the color temperature and color index is created of white light.

2. The light source according to claim 1, characterized in that at least one of the values a, b, C and d is larger than 0.01.

3. The light source according to claim 1 or 2, characterized in that the phosphor fraction of silicon may be replaced by gallium.

4. The light source according to one of claims 1 to 3, the ex is different, however, it contains additional phosphor from the group of aluminates of alkaline-earth metals, activated by divalent europium and/or manganese and/or other additional phosphor emitting red light, from the group of Y(V,P,Si)₄: Eu,Bi,Y₂O₂S : Eu,Bi or disilicate alkaline-earth magnesium : Eu²⁺, MP²⁺with the formula

Me_(3-x-y)gSi₂O₈: xEu, yMn,

where

of 0.005<x<0,5 0,005<<0,5

and Me=BA and/or Sr and/or CA.

5. The light source according to one of claims 1 to 4, characterized in that the monovalent ions, in particular chlorides and/or alkali metals, incorporated into the crystal lattice of the phosphor.

6. The light source according to one of claims 1 to 5, characterized in that the led emits light in the spectral region from 300 to 500 nm, so that the phosphor emits light in the spectral range from 430 to 650 nm and the fact that the light source emits white light with a color reproduction index R_and>70.

7. The light source according to one of claims 1 to 6, characterized in that one or more led chips (1) placed on a printed circuit Board (2) inside the reflector (4) and the phosphor (6) dispersed on a light disk (5)above the reflector (4).

8. The light source according to one of claims 1 to 6, characterized in that one or more led chips (1) placed on a printed circuit Board (2) inside the reflector (4) and luminova the (6) applied to the reflector (4).

9. The light source according to claim 7 or 8, characterized in that the led chips (1) filled transparent molding mass (3, 3’)having a domed shape.

10. The light source according to one of claims 1 to 6, characterized in that the phosphor dispersed in the casting mass (3), which connects the world (1’) of the led chips (1) PCB (2) and a polymer lens (7) without gas inclusions, and polymer lens (7) and the casting mass (3) have refractive indices that differ by no more than 0.1.

11. The light source of claim 10, wherein the polymeric lens (7) is a hollow spherical or elliptical shape, filled with the filling mass (3), so led the world (1’) is fixed at a slight distance from the polymeric lens (7).

12. The light source according to one of claims 1 to 11, characterized in that the phosphor suspended in a predominantly inorganic matrix.

13. The light source according to one of claims 4 and 12, characterized in that the matrices separately suspended at least two phosphor, which are placed one behind the other in the direction of light propagation.

14. The light source according to one of claims 1 to 13, characterized in that the average grain size d₅₀for three-dimensional distribution of the phosphor is in the range from 2 to 20 microns.