WO2017033288A1

WO2017033288A1 - Light-emitting device

Info

Publication number: WO2017033288A1
Application number: PCT/JP2015/073864
Authority: WO
Inventors: 仁室伏; 匡紀星野; 芳憲田中
Original assignee: サンケン電気株式会社
Priority date: 2015-08-25
Filing date: 2015-08-25
Publication date: 2017-03-02

Abstract

A light-emitting device is provided with: a first light-emitting diode which includes a first blue light emitting element emitting first emitted light having a relatively short peak wavelength and a first fluorescence material layer emitting first excited light by being excited by the first emitted light, and which outputs first mixed color light of first chromaticity in which the first emitted light and the first excited light are mixed; and a second light-emitting diode which includes a second blue light emitting element emitting second emitted light having a relatively long peak wavelength and a second fluorescence material layer emitting second excited light by being excited by the second emitted light, and which outputs second mixed color light of second chromaticity in which the second emitted light and the second excited light are mixed. The first chromaticity and the second chromaticity are located at symmetric positions with respect to a predetermined chromaticity along the color temperature characteristics of black-body radiation in an xy chromaticity diagram, and the first mixed color light and the second mixed color light are mixed to output output light of predetermined chromaticity.

Description

Light emitting device

The present invention relates to a light emitting device that excites a phosphor and outputs light.

A light emitting device using a light emitting diode (LED) composed of a light emitting element and a phosphor excited by the light emitting element has been put into practical use. In a lighting device having a color temperature of about 2000K to 8000K, it is possible to make the output light of the lighting device have a desired chromaticity by mixing and mixing light having different chromaticities emitted from a plurality of LEDs. . Here, “mixing” is to mix a plurality of lights having different characteristics such as chromaticity. According to this method, desired output light can be obtained by combining LEDs having different chromaticities. Therefore, it is possible to reduce the number of LEDs that cannot be used for the lighting fixture, and to reduce the waste of the LEDs. Further, the degree of freedom of chromaticity can be increased.

For this reason, various methods using a light emitting element and a phosphor have been studied. For example, there has been proposed a light-emitting device that excites a phosphor by two blue light-emitting elements selected from different wavelength ranges and mixes light emitted from the phosphor (for example, see Patent Document 1). When white light is generated by excitation by one light emitting element, chromaticity variation of white light occurs due to manufacturing variation of the light emitting element. In the light emitting device described in Patent Document 1, the manufacturing variation of the light emitting element is canceled by exciting the phosphor having a small characteristic variation with the two blue light emitting elements.

Japanese Patent No. 4932978

In the CIExy chromaticity diagram, when the emitted light of LEDs having the same product of chromaticity and luminous intensity is mixed, an additive law is established that the chromaticity of the mixed color light becomes the average value of the chromaticity of these LEDs. For this reason, the above-mentioned method of mixing a plurality of emitted lights and mixing them is effective for variations in chromaticity and luminous intensity.

On the other hand, lighting equipment also requires stable color rendering with little variation. For this reason, even when the light emitting element and the phosphor are used, it is necessary that the color rendering properties are not reduced or varied by mixing. However, in order to suppress the variation in color rendering properties, it is necessary to consider the overlap of spectra where the additive law is not satisfied. Until now, the method for reducing the variation in color rendering properties has not been sufficiently studied. An object of the present invention is to provide a light emitting device that excites a phosphor by a light emitting element and outputs output light in which variation in color rendering properties is suppressed.

According to one aspect of the present invention, (a) the first blue light emitting element that emits the first emitted light having a relatively short peak wavelength, and the first blue light emitting element excited by the first emitted light, A first light emitting diode having a first phosphor layer that emits excitation light, and that outputs first mixed color light having a first chromaticity obtained by mixing the first emitted light and the first excitation light; (A) a second blue light emitting element that emits second emitted light having a relatively long peak wavelength, and a second that emits second excited light when excited by the second emitted light. A second light emitting diode having a phosphor layer and outputting a second mixed light of a second chromaticity obtained by mixing the second outgoing light and the second excitation light, and the first chromaticity And the second chromaticity are in a symmetric position with respect to a predetermined chromaticity along the color temperature characteristic of the black body radiation in the xy chromaticity diagram, and the first mixed color light and the second mixed color light are Emitting device is provided by mixing outputs the output light of a predetermined chromaticity.

According to the present invention, it is possible to provide a light emitting device that excites a phosphor with a light emitting element and outputs output light in which variation in color rendering is suppressed.

It is a schematic diagram which shows the structure of the light-emitting device which concerns on the 1st Embodiment of this invention. It is a chromaticity diagram for demonstrating the chromaticity of the output light of the light emitting diode with which the light-emitting device which concerns on the 1st Embodiment of this invention is provided. It is a chromaticity diagram for demonstrating the range of chromaticity of the output light of the light emitting diode with which the light-emitting device which concerns on the 1st Embodiment of this invention is provided. It is a graph which shows the spectrum of black body radiation. It is another chromaticity diagram for demonstrating the chromaticity of the output light of the light emitting diode with which the light-emitting device which concerns on the 1st Embodiment of this invention is provided. It is a graph which shows the spectrum of the output light obtained by the simulation about the light emitting diode using a blue light emitting element and fluorescent substance. It is the graph which expanded a part of FIG. It is a table | surface which shows the color rendering index of the output light obtained by the simulation about the light emitting diode using a blue light emitting element and fluorescent substance. It is a graph which shows the example of distribution of the peak wavelength of a blue light emitting element. It is a graph which shows the other example of distribution of the peak wavelength of a blue light emitting element. It is a schematic diagram which shows the structure of the light-emitting device which concerns on the 2nd Embodiment of this invention.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes the shape, structure, arrangement, etc. of components. It is not specified to the following. The embodiment of the present invention can be variously modified within the scope of the claims.

(First embodiment)
As shown in FIG. 1, the light emitting device 1 according to the first embodiment of the present invention includes a first light emitting diode 10 that outputs a first color mixture light L1 having a first chromaticity, and a second chromaticity. And the second light emitting diode 20 that outputs the second mixed color light L2. The light emitting device 1 outputs output light L0 having a predetermined chromaticity obtained by mixing the first mixed color light L1 and the second mixed color light L2. The chromaticities of the first mixed color light L1 and the second mixed color light L2 are adjusted so that the output light L0 has a predetermined chromaticity. Details of these chromaticities will be described later.

The first light-emitting diode 10 includes a first blue light-emitting element 11 that emits first emitted light having a relatively short wavelength (peak wavelength) of a peak value of relative intensity in an emission spectrum, The first phosphor layer 12 is excited by the emitted light and emits the first excitation light. The first color mixture light L1 is light obtained by mixing the first emission light and the first excitation light.

The second light emitting diode 20 is excited by the second blue light emitting element 21 that emits the second emitted light whose peak wavelength is relatively longer than that of the first emitted light, and the second emitted light. And a second phosphor layer 22 that emits second excitation light. The second color mixture light L2 is light in which the second emitted light and the second excitation light are mixed.

The first light emitting diode 10 shown in FIG. 1 has a structure in which the first blue light emitting element 11 is arranged on the bottom surface of the concave portion of the first package 13 having the concave portion. The concave portion of the first package 13 is filled with the first phosphor layer 12. The second light emitting diode 20 has a structure in which the second blue light emitting element 21 is disposed on the bottom surface of the concave portion of the second package 23 having the concave portion. The concave portion of the second package 23 is filled with the second phosphor layer 22. The first phosphor layer 12 and the second phosphor layer 22 contain a green phosphor 201 and a red phosphor 202. Silicon resin or the like can be used for the first phosphor layer 12 and the second phosphor layer 22.

As shown in FIG. 1, the first light emitting diode 10 and the second light emitting diode 20 are mounted on the substrate 40 in the lamp 50. The first mixed color light L1 and the second mixed color light L2 are mixed in the lamp 50, and output light L0 having a predetermined chromaticity C0 is output from the lamp 50. For the lamp 50, for example, a translucent resin cover or the like can be used.

The first blue light emitting element 11 and the second blue light emitting element 21 are blue LED light emitting elements that emit blue light. Electrical wiring (not shown) is disposed on the substrate 40, and the first blue light emitting element 11 and the second blue light emitting element 21 are connected to the electrical wiring, respectively. When a voltage is applied through the electric wiring, a driving current flows, and the first blue light emitting element 11 and the second blue light emitting element 21 emit light. As the first blue light emitting element 11 and the second blue light emitting element 21, for example, an indium gallium nitride (InGaN) blue LED light emitting element can be used.

The first blue light emitting element 11 and the second blue light emitting element 21 are respectively selected from two light emitting element groups whose peak wavelengths are in different wavelength ranges. That is, the first blue light-emitting element 11 is included in a group of blue light-emitting elements that emits blue light having a relatively short wavelength (hereinafter referred to as “short wavelength group”). The second blue light-emitting element 21 is included in a group of blue light-emitting elements that emits blue light having a longer wavelength than that of the short-wavelength group (hereinafter referred to as “long wavelength group”).

The green phosphor 201 is excited by the light emitted from the first blue light emitting element 11 or the second blue light emitting element 21 and emits green light. On the other hand, the red phosphor 202 is excited by the light emitted from the first blue light-emitting element 11 or the second blue light-emitting element 21 and emits red light. That is, the first light emitting diode 10 includes the blue light emitted from the first blue light emitting element 11 and the green light and the red phosphor emitted from the green phosphor 201 included in the first phosphor layer 12. The first mixed color light L1 in which the red light emitted from 202 is mixed is output. The second light emitting diode 20 includes blue light emitted from the second blue light emitting element 21, and green light emitted from the green phosphor 201 included in the second phosphor layer 22 and the red phosphor 202. The second mixed color light L2 in which the emitted red light is mixed is output.

Accordingly, in consideration of the peak wavelength of the first blue light-emitting element 11, the first color mixture light is adjusted by adjusting the blending ratio of the green phosphor 201 and the red phosphor 202 included in the first phosphor layer 12. The first chromaticity of L1 is set. Similarly, by considering the peak wavelength of the second blue light emitting element 21 and adjusting the blending ratio of the green phosphor 201 and the red phosphor 202 contained in the second phosphor layer 22, the second color mixture light is obtained. The second chromaticity of L2 is set.

An example of the relationship among the first chromaticity C1 of the first mixed color light L1, the second chromaticity C2 of the second mixed color light L2, and the predetermined chromaticity C0 of the output light L0 is shown in FIG. Shown in the figure. The first chromaticity C1 and the second chromaticity C2 are in symmetrical positions with respect to the chromaticity C0. As a result, an additive law is established for the chromaticity, so that variation in chromaticity with respect to the output light L0 is suppressed. Further, as shown in FIG. 2, the first chromaticity C1 and the second chromaticity C2 are set so as to be positioned along the color temperature characteristic T of black body radiation in the xy chromaticity diagram. The color temperature characteristic T is a characteristic of the color temperature of light that is approximately expressed by the output light L0 of the light emitting device 1.

The first chromaticity C1 and the second chromaticity C2 are preferably closer to the characteristic line of the color temperature characteristic T. At least, in the xy chromaticity diagram, when the chromaticity C0 is the origin, the first quadrant is the same as the color temperature characteristic T, and the x coordinate and the y coordinate are within ± 0.05 from the chromaticity C0. The chromaticity C1 and the second chromaticity C2 are located. FIG. 3 shows a position where the first chromaticity C1 can be taken as a range A1 and a position where the second chromaticity C2 can be taken as a range A2 in the xy chromaticity diagram. Range A1 and range A2 are rectangular ranges with one side of 0.01.

Thus, by setting the first chromaticity C1 and the second chromaticity C2 to the chromaticity along the color temperature characteristic T of the black body radiation, the color temperature of the light for expressing the chromaticity of the output light L0 is obtained. You can get closer. According to the study by the present inventors, it is preferable that the first chromaticity C1 and the second chromaticity C2 are in the range of chromaticity C0 to 0.05.

Note that the first chromaticity C1 of the first mixed-color light L1 and the second chromaticity C2 of the second mixed-color light L2 are set according to the color temperature of light that is desired to be approximately expressed by the output light L0. Is preferred. As shown in FIG. 4, the slope of the relative intensity with respect to the wavelength of the spectrum of black body radiation varies depending on the color temperature. That is, when the color temperature is 5500 K or less, the relative intensity is smaller as the wavelength is shorter in the wavelength band of blue light. On the other hand, when the color temperature is higher than 5500 K, the shorter the wavelength in the blue light wavelength band, the greater the relative intensity.

For this reason, when the color temperature of blackbody radiation is 5500K or less, the first chromaticity C1 is higher than the predetermined chromaticity C0, and the second chromaticity C2 is lower than the predetermined chromaticity C0. As described above, the chromaticity of the first mixed color light L1 and the second mixed color light L2 is set. On the other hand, when the color temperature of the black body radiation is higher than 5500K, the first chromaticity C1 is lower than the predetermined chromaticity C0, and the second chromaticity C2 is higher than the predetermined chromaticity C0. As described above, the chromaticity of the first mixed color light L1 and the second mixed color light L2 is set. As already described, the chromaticity of the first mixed color light L1 and the second mixed color light L2 can be set by the blending ratio of the green phosphor 201 and the red phosphor 202.

The xy chromaticity diagram shown in FIG. 2 shows the first chromaticity C1 of the first mixed color light L1 and the second chromaticity of the second mixed color light L2 when the color temperature of the black body radiation is 5500K or less. It is an example of the relationship between C2 and predetermined chromaticity C0. Relationship between the first chromaticity C1 of the first mixed light L1, the second chromaticity C2 of the second mixed light L2, and the predetermined chromaticity C0 when the color temperature of the black body radiation is higher than 5500K. An example is shown in the xy chromaticity diagram of FIG.

According to the study by the present inventors, the following effects can be obtained by setting the first chromaticity C1 and the second chromaticity C2 as described above according to the color temperature of the black body radiation. It was.

First, the variation in color rendering in the output light L0 is suppressed. This is an effect obtained by mixing light emitted from a plurality of light emitting diodes. FIG. 6 shows a simulation result of a spectrum of mixed color light of a light emitting diode using a blue light emitting element and a phosphor. A characteristic P1 indicated by a solid line in FIG. 6 is a spectrum of mixed color light of the sample S1 using a plurality of blue light emitting elements having peak wavelengths in the range of 450 nm to 462.5 nm. Assuming that the color temperature of blackbody radiation is 5000K, sample S1 generates a mixed color light of high chromaticity with a blue light emitting element selected from the short wavelength group and emits blue light selected from the long wavelength group. The device produced mixed color light with low chromaticity. A characteristic P2 indicated by a broken line in FIG. 6 is a spectrum of mixed color light of the sample S2 using a single blue light emitting element having a peak wavelength in the range of 455 nm to 457.5 nm. In addition, YAG (Ga dope) and SCASN were used for the phosphor.

As shown in FIG. 6, the longer wavelength side of the blue wavelength region swells in the wavelength direction in the characteristic P1 than in the characteristic P2. Only the long wavelength side swells due to the absorption characteristics of the phosphor. FIG. 7 shows an enlarged view of the blue wavelength region of FIG. The sharper the peak of the spectrum, the greater the variation in color rendering. Therefore, the expansion of the spectrum as shown in FIGS. 6 and 7 indicates that the variation in color rendering properties is suppressed. The characteristic P1 does not have a plurality of peaks because a plurality of blue light emitting elements having continuous peak wavelengths are used.

Further, by setting the first chromaticity C1 and the second chromaticity C2 as described above, the average color rendering index Ra and the special color rendering index R9, which are main color rendering properties, are improved in the output light L0. The effect was obtained. FIG. 8 shows the color rendering index of the output light of sample S1 and the color rendering index of the output light of sample S2.

Note that according to the study by the present inventors, by increasing the number of blue light emitting elements whose wavelength peaks are located at both ends of the distribution, the expansion of the spectrum is increased and the color rendering index is further improved.

As described above, the light emitting device 1 can be configured by using blue light emitting elements whose peak wavelengths vary over a wide range. That is, a group of blue light emitting elements having a large peak wavelength distribution due to manufacturing variations can be used with little waste.

For example, it is assumed that the distribution of the peak wavelength of the prepared blue light emitting element is as shown in FIG. Here, the width from the shortest wavelength of the short wavelength group G1 to the longest wavelength of the long wavelength group G2 is, for example, about 40 nm. At this time, the blue light emitting elements on the short wavelength side are set as the short wavelength group G1 and the blue light emitting elements on the long wavelength side are set as the long wavelength group G2 around the center wavelength λc of the peak wavelength distribution. Then, the blending ratio of the green phosphor 201 and the red phosphor 202 included in the first phosphor layer 12 is adjusted in accordance with the wavelength of the short wavelength group G1, and the chromaticity of the first mixed color light L1 is set to the first. The chromaticity C1 is set. Similarly, the mixing ratio of the green phosphor 201 and the red phosphor 202 included in the second phosphor layer 22 is adjusted to correspond to the wavelength of the long wavelength group G2, and the chromaticity of the second mixed light L2 is changed to the first. 2 chromaticity C2.

When the color temperature of light desired to be expressed by the output light L0 is 5500K or less, the blending ratio of the respective phosphors in the first phosphor layer 12 and the second phosphor layer 22 is set as follows. That is, the first light-mixed light L1 emitted from the first light-emitting diode 10 is excited by the blue light-emitting elements included in the short wavelength group G1 so that the first chromaticity C1 of the first mixed color light L1 is higher than the chromaticity C0. The blending ratio of the phosphors in the first phosphor layer 12 is set. Further, the second light-emitting diode 20 is excited by the blue light-emitting elements included in the long wavelength group G2 such that the second chromaticity C2 of the second mixed light L2 emitted from the second light-emitting diode 20 is lower than the chromaticity C0. The mixing ratio of the phosphor in the second phosphor layer 22 is set.

On the other hand, when the color temperature of light desired to be expressed by the output light L0 is higher than 5500K, the short wavelength group G1 is set so that the first chromaticity C1 of the first mixed color light L1 is lower than the chromaticity C0. The blending ratio of the phosphor in the first phosphor layer 12 excited by the included blue light emitting element is set. In addition, the phosphor in the second phosphor layer 22 excited by the blue light emitting element included in the long wavelength group G2 so that the second chromaticity C2 of the second mixed color light L2 is higher than the chromaticity C0. Is set.

As described above, the blue light emitting element is divided into the short wavelength group G1 and the long wavelength group G2, and the first light emitting diode 10 and the second light emitting diode 20 are configured according to the respective chromaticities. Is completed. Thereby, the number of blue light emitting elements which cannot be used can be suppressed. In addition, it is possible to suppress generation of useless light-emitting diodes that cannot be used as compared with the case where a light-emitting device is configured by combining light-emitting diodes according to the characteristics of the completed light-emitting diodes.

The green phosphor 201 includes blue light such as cerium-activated yttrium aluminate phosphor (YAG), cerium-activated lutetium aluminum garnet phosphor (LuAG), and europium-activated alkaline earth silicate phosphor (BOSS). Common green phosphors that are excited can be used. For example, YAG-based Y ₃ Al ₅ O ₁₂ : Ce ⁺³ , Y ₃ (Al, Ga) ₅ O ₁₂ : Ce ⁺³ , (Y, Gd) ₃ Al ₅ O ₁₂ : Ce ⁺³ , LuAG-based Lu ₃ A ₁₅ O ₁₂ : Ce ⁺³ , BOSS-based (Ba, Sr, Ca) ₂ SiO ₄ : Eu ⁺² , LSN phosphor La ₃ Si ₆ N ₁₁ : Ce ⁺³ , CSS phosphor Ca ₃ ( Sc, Mg) ₂ Si ₃ O ₁₂ : Ce ⁺³ , scandate-based CaSc ₂ O ₄ : Ce ⁺³ and the like, scandium oxide-based Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ⁺³ and Those similar to the above can be used for the green phosphor 201.

As the red phosphor 202, aluminum nitride-based CaAlSiN ₃ : Eu ⁺² , (Sr, Ca) AlSiN ₃ : Eu ⁺² and the like can be used.

By the way, in FIG. 1, the case where the 1st light emitting diode 10 and the 2nd light emitting diode 20 which are contained in the light-emitting device 1 are one each was shown in illustration. However, any number of first light emitting diodes 10 and second light emitting diodes 20 may be used depending on the luminous intensity required for the light emitting device 1. For example, several tens to several hundreds of first light emitting diodes 10 and second light emitting diodes 20 are arranged in the lamp 50. The number of the first light emitting diodes 10 and the second light emitting diodes 20 is adjusted so that the output light L0 has a predetermined chromaticity C0 by mixing.

As described above, in the light emitting device 1 according to the first embodiment of the present invention, the blue light emitting elements selected from the groups having different peak wavelengths are used, and the color mixture is different from the predetermined chromaticity C0. A first light emitting diode 10 and a second light emitting diode 20 that output light are configured. Then, the first mixed color light L1 output from the first light emitting diode 10 and the second mixed color light L2 output from the second light emitting diode 20 are mixed, and output light L0 is output from the light emitting device 1. Is done. At this time, the first chromaticity C1 of the first mixed color light L1 and the second chromaticity C2 of the second mixed color light L2 are colored along the color temperature characteristic T of blackbody radiation in the xy chromaticity diagram. Set to a symmetrical position about degree C0. As a result, it is possible to provide the light emitting device 1 that outputs the output light L0 having the chromaticity C0 in which variations in chromaticity and color rendering are suppressed. In addition, the light emitting device 1 is economical because it can use blue light emitting elements whose peak wavelengths vary over a wide range.

(Second Embodiment)
FIG. 9 shows a case where blue light emitting elements are classified into two groups according to the distribution of peak wavelengths. However, the blue light emitting elements may be classified into three groups as shown in FIG. In the example shown in FIG. 10, a medium wavelength group G3 including a blue light emitting element having a peak wavelength in a wavelength band including the central wavelength λc of the distribution is set between the short wavelength group G1 and the long wavelength group G2. . For example, the width from the shortest wavelength of the short wavelength group G1 to the longest wavelength of the long wavelength group G2 is about 40 nm, and the distribution width of the medium wavelength group G3 is about 5 nm.

Light emitting device using first blue light emitting element 11 included in short wavelength group G1, second blue light emitting element 21 included in long wavelength group G2, and third blue light emitting element 31 included in medium wavelength group G3 An example in which 1 is configured is shown in FIG. The light-emitting device 1 shown in FIG. 11 includes a third blue light emission in addition to the first light-emitting diode 10 having the first blue light-emitting element 11 and the second light-emitting diode 20 having the second blue light-emitting element 21. The difference from the light emitting device 1 shown in FIG. 1 is that a third light emitting diode 30 having an element 31 is further provided. About another structure, it is the same as that of the light-emitting device 1 shown in FIG. That is, also in the light emitting device 1 shown in FIG. 11, the first chromaticity C1 of the first mixed color light L1 output from the first light emitting diode 10 and the second mixed color output from the second light emitting diode 20 are used. The second chromaticity C2 of the light L2 is in a symmetrical position with respect to a predetermined chromaticity C0 along the color temperature characteristic of black body radiation in the xy chromaticity diagram.

The third light emitting diode 30 includes a third blue light emitting element 31 and a third phosphor layer that is excited by the third emitted light emitted from the third blue light emitting element 31 and emits the third excitation light. 32. The peak wavelength of the third emitted light is the peak wavelength of the first emitted light emitted from the first blue light emitting element 11 and the peak wavelength of the second emitted light emitted from the second blue light emitting element 21. It is in the middle. As shown in FIG. 11, in the third light emitting diode 30, the third blue light emitting element 31 is disposed on the bottom surface of the concave portion of the third package 33 having the concave portion, and the concave portion of the third package 33 is the third fluorescent light. The structure is filled with the body layer 32.

The third light emitting diode 30 outputs the third mixed light L3 in which the third emitted light and the third excitation light are mixed. At this time, the blending ratio of the green phosphor 201 and the red phosphor 202 included in the third phosphor layer 32 so that the chromaticity of the third mixed color light L3 becomes a predetermined chromaticity C0 in the xy chromaticity diagram. Has been adjusted. Therefore, the first color mixture light L1 output from the first light emitting diode 10, the second color mixture light L2 output from the second light emitting diode 20, and the third color mixture light L3 output from the third light emitting diode 30. , The output light L0 having the chromaticity C0 in which variations in chromaticity and color rendering properties are suppressed can be output.

In the light emitting device 1 shown in FIG. 11, the first light emitting diode 10, the second light emitting diode 20, and the third light emitting diode 30 are mounted on the substrate 40 in the lamp 50. The first mixed color light L 1, the second mixed color light L 2, and the third mixed color light L 3 are mixed in the lamp 50, and output light L 0 having a predetermined chromaticity C 0 is output from the lamp 50.

Others are substantially the same as those in the first embodiment, and redundant description is omitted. For example, a plurality of first light emitting diodes 10, second light emitting diodes 20, and third light emitting diodes 30 may be disposed in the lamp 50. At this time, the number of the first light emitting diode 10, the second light emitting diode 20, and the third light emitting diode 30 is adjusted so that the output light L0 has a predetermined chromaticity C0 by mixing.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

In the above description, the example in which the blue light emitting elements are classified into two to three groups according to the peak wavelength has been described. However, the blue light emitting elements may be classified into four or more groups. At this time, the chromaticities of the light emitting diodes using the blue light emitting elements of the group symmetrical to each other with respect to the center wavelength of the peak wavelength distribution are set so as to be symmetric with respect to the predetermined chromaticity C0.

Thus, it goes without saying that the present invention includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

The light-emitting device of the present invention can be used for a light-emitting device that emits light by exciting a phosphor with a light-emitting element.

Claims

A first blue light emitting element that emits first emitted light having a relatively short peak wavelength, and a first phosphor layer that is excited by the first emitted light and emits first excited light. A first light emitting diode that outputs a first mixed light of a first chromaticity obtained by mixing the first emitted light and the first excitation light;
A second blue light emitting element that emits second emitted light having a relatively long peak wavelength, and a second phosphor layer that is excited by the second emitted light and emits second excited light. A second light emitting diode that outputs a second mixed light of a second chromaticity obtained by mixing the second emitted light and the second excitation light, and
The first chromaticity and the second chromaticity are in a symmetrical position with respect to a predetermined chromaticity along a color temperature characteristic of black body radiation in the xy chromaticity diagram,
A light emitting device characterized in that the first mixed color light and the second mixed color light are mixed to output output light of the predetermined chromaticity.
In the xy chromaticity diagram, when the predetermined chromaticity is used as an origin, the x- and y-coordinates are ± 0.05 from the predetermined chromaticity in the same quadrant as the color temperature characteristic of the black body radiation. 2. The light emitting device according to claim 1, wherein the first chromaticity and the second chromaticity are located in a range.
When the color temperature of the black body radiation is 5500K or less, the first chromaticity is higher than the predetermined chromaticity, and the second chromaticity is lower than the predetermined chromaticity,
When the color temperature of the black body radiation is higher than 5500K, the first chromaticity is lower than the predetermined chromaticity and the second chromaticity is higher than the predetermined chromaticity. The light-emitting device according to claim 1.
The blending ratio of the green phosphor and the red phosphor in the first phosphor layer is set so that the first light mixture of the first chromaticity is output from the first light emitting diode,
The blending ratio of the green phosphor and the red phosphor in the second phosphor layer is set so that the second light mixture of the second chromaticity is output from the second light emitting diode. The light-emitting device according to claim 1.
A third blue light emitting element that emits third emitted light whose peak wavelength is intermediate between the first blue light emitting element and the second blue light emitting element, and the third wavelength emitted by the third emitted light are excited by the third emitted light. A third phosphor layer that emits the third excitation light and outputs a third color mixture light of the predetermined chromaticity obtained by mixing the third emission light and the third excitation light. The light emitting diode is further provided,
2. The light emitting device according to claim 1, wherein the output light is output by mixing the first mixed light, the second mixed light, and the third mixed light.
The blending ratio of the green phosphor and the red phosphor in the third phosphor layer is set so that the third light mixture of the predetermined chromaticity is output from the third light emitting diode. The light-emitting device according to claim 5.