JP4017015B2 - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device in which a generation of chromaticity deviation due to ambient temperature change is suppressed. <P>SOLUTION: In the light emitting device including a light source and a plurality of phosphors which absorbs at least part of light emitted from the light source and emits light having a different wavelength, the phosphor includes at least one first phosphor located on the light source, and at least one or more kinds of second phosphors in which at least part of the emitting light is absorbed by the first phosphor while the first phosphor is located nearer to the light source side than the second phosphor. Furthermore, the second phosphor is located on at least one light source and/or at least one light source which is different from the at least one light source. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention is a fluorescent display tube, display, PDP, CRT, FL, FED, projection tube, etc., in particular, a blue light emitting diode or an ultraviolet light emitting diode, and a combination of a blue light emitting diode or an ultraviolet light emitting diode and a predetermined phosphor. The present invention relates to a phosphor used in a white light emitting device and the like that is extremely excellent in light emission characteristics using a light source as an excitation light source. In addition, the light emitting device having the phosphor according to the present invention can be used for fluorescent lamps for store front lighting, medical spot lighting, etc., as well as backlight light sources for liquid crystal displays, light sources for projectors, and light emission. It can also be applied to the field of diodes (LEDs).

  As a light-emitting device using LEDs, color mixing light emitted from a light-emitting element (LED chip) (hereinafter referred to as “LED light”) and light obtained by wavelength-converting part of the LED light with a phosphor Thus, there is a light emitting device that obtains a desired emission color. For example, an LED that emits white light (hereinafter referred to as “white LED”) is an LED that emits blue light having an emission spectrum peak wavelength of about 460 nm, and an yttrium / aluminum / garnet system having an excitation absorption spectrum peak wavelength of around 460 nm. A light emitting diode that obtains white light by mixing yellow light generated by wavelength conversion of blue light by a phosphor (hereinafter referred to as “YAG phosphor”). In such a white LED, a phosphor that emits light having a peak wavelength of an emission spectrum in a red region (hereinafter referred to as “red”) for the purpose of improving the color rendering property of mixed color light obtained by additive color mixture of blue and yellow. May be used by mixing with YAG phosphor. For example, in a light emitting device disclosed in Japanese Patent Laid-Open No. 2000-244021 (Patent Document 1), a fluorescent layer in which a red phosphor and a YAG phosphor are mixed is provided on an LED. In such a light emitting device, the light from the YAG phosphor that absorbs the LED light and emits light, the light from the red phosphor that emits the light by absorbing the LED light, and the LED light are mixed, A red light component is added to the conventional white LED to improve the color rendering.

JP 2000-244021 A

  However, YAG phosphors whose emission spectrum wavelength is in the range of 500 nm to 750 nm and red phosphors whose excitation absorption spectrum peak wavelength is in the range of 350 nm to 600 nm, that is, reflection with respect to light having a wavelength of 500 nm or more. When the red phosphor that absorbs light of 500 nm or more is mixed and formed as a phosphor layer because the rate is low, the red phosphor absorbs part of the light emission of the YAG phosphor. Therefore, as shown in FIG. 7, the peak wavelength of the emission spectrum by the YAG phosphor is hardly observed in the wavelength range of 500 nm to 550 nm, and the color rendering property of the mixed color light output from the light emitting device is sufficiently improved. I could not. Further, when the light-emitting device is used as an illumination light source that continuously emits strong light, for example, the excitation efficiency of various phosphors is reduced due to heat generation of the light-emitting elements, and thus the luminous flux [lm] of the entire light-emitting device is reduced. Problems arise. Furthermore, when a light emitting device is formed by combining a plurality of phosphors whose excitation efficiencies are reduced at different rates due to heat generation, the difference in the light emission output of each phosphor changes as the ambient temperature rises, so that light is emitted from the light emitting device. There was a color shift observed at a position where the chromaticity of light deviated from the desired chromaticity. Even when such color misregistration is slight, when the light emitting device is used as a light source of a liquid crystal projector, for example, it has a large influence on the color tone of a color image projected and projected on a screen. Occurs.

  Therefore, the present invention provides a light-emitting device that improves color rendering properties as compared to the prior art and can suppress the decrease in luminous flux [lm] and the occurrence of chromaticity deviation even when the ambient temperature changes. Objective.

To achieve the above object, the present invention provides a light source, a plurality of phosphor layers that absorb at least part of light from the light source and emit light having different wavelengths, and a package in which the light source is disposed. The light source has a first light source and a second light source, the package has a step, and a second recess in which the second light source is placed. And a first recess that is in the second recess and is recessed from the bottom surface of the second recess in a direction opposite to the emission observation surface, and on which the first light source is placed. The phosphor layer includes a first phosphor layer and a second phosphor layer, and the first phosphor layer is disposed in the first recess, release the first light also longer wavelength than the light from the at least part absorbs the first light source of the light from the first light source And, the second phosphor layer, the light from the second light source, and the first at least a portion of light of the light from the light source, than the light from the absorber to the second light source The second light having a long wavelength is emitted, the peak wavelength of the first light is longer than the peak wavelength of the second light, and the first light from the first phosphor is The present invention relates to a light emitting device that is diffused without being absorbed by the second phosphor.

The present invention relates to a light emitting device comprising: a light source; a plurality of phosphor layers that absorb at least part of light from the light source and emit light having different wavelengths; and a package in which the light source is disposed. Each of the light sources has a first light source and a second light source capable of emitting light in a blue region, and the package is provided with a step, and a second light source on which the second light source is placed. A first recess that is in the second recess and is recessed from the bottom surface of the second recess in a direction opposite to the emission observation surface, and on which the first light source is placed The phosphor layer includes a first phosphor layer and a second phosphor layer, and the first phosphor layer is disposed in the first recess, Absorbs at least part of the light from the first light source and has a peak wavelength of the emission spectrum in the red region The first phosphor emits light, and the second phosphor layer absorbs light from the second light source and at least part of light from the first light source, and absorbs yellow light from a green region. The present invention relates to a light emitting device that emits second light having a peak wavelength of an emission spectrum and diffuses the first light from the first phosphor without being absorbed by the second phosphor.

  According to the present invention, it is possible to form a light-emitting device with improved color rendering as compared with the prior art.

  In a light-emitting device comprising a light source and a plurality of phosphors that absorb at least part of light from the light source and emit light having different wavelengths, the phosphor is a first fluorescence on at least one light source. And at least one or more types of second phosphors that are absorbed by the first phosphor, wherein the first phosphor is more than the second phosphor. A light emitting device on the light source side;

  With such a structure, a light-emitting device with improved color rendering can be obtained as compared with the related art.

  The second phosphor may be on the at least one light source and / or on at least one light source different from the at least one light source.

  In this way, by using a plurality of LED chips and directly exciting the phosphors covering the LED chips, the color rendering property is improved as compared with the prior art, and a light emitting device capable of emitting high luminance can be obtained. .

  The light emitting device includes a first recess for mounting the first phosphor and at least one light source, and the first recess, and mounts the second phosphor and at least one light source. And a second recess.

  With such a structure, a light emitting device with further improved color rendering can be obtained.

  The first phosphor includes N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, Zr, and A nitride-based phosphor containing at least one element selected from Hf and activated by at least one element selected from rare earth elements may also be included.

  With such a structure, a light-emitting device with further improved color rendering can be obtained.

  The second phosphor includes Y and Al, and at least one element selected from Lu, Sc, La, Gd, Tb, Eu, and Sm, and one element selected from Ga and In And an yttrium-aluminum-garnet phosphor activated with at least one element selected from rare earth elements.

  With such a structure, a light-emitting device with further improved color rendering can be obtained.

  In addition, the second phosphor may have a configuration in which a light emission output reduction rate with respect to a temperature rise is substantially equal to that of the first phosphor.

  By adopting such a configuration, the color rendering property is improved as compared with the conventional technology, and a light emitting device that suppresses the decrease in luminous flux [lm] and the occurrence of chromaticity deviation even when the ambient temperature changes can be obtained. Is possible.

  The light source may be a semiconductor light emitting element.

  With such a structure, color rendering can be improved as compared with the conventional technology, and a light-emitting device with low power consumption and a small size can be obtained.

  The light source may be a light source that combines a semiconductor light emitting element and a phosphor that emits light having different wavelengths by absorbing at least part of the light from the semiconductor light emitting element.

  With such a structure, color rendering can be improved as compared with the conventional technology, and a light-emitting device with low power consumption and a small size can be obtained.

  The light source may have an emission spectrum peak wavelength of 350 nm to 530 nm.

  With such a structure, a light-emitting device with further improved color rendering can be obtained.

  The light-emitting device can also be used as a backlight light source for a liquid crystal display or an illumination light source.

  By adopting such a configuration, it is possible to improve the color rendering and to form a liquid crystal display or an illumination light source in which color misregistration is less likely to occur due to changes in ambient temperature as compared with the prior art.

  The light emission outputs of the light source that emits the light that excites the first phosphor and the light source that emits the light that excites the second phosphor can be independently controlled.

  With such a configuration, a light emitting device capable of freely adjusting the color temperature of the mixed color light can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device to the following. Further, the size and positional relationship of the members shown in the drawings are exaggerated for clarity of explanation.

  The phosphor used in the present invention includes a first phosphor on at least one light emitting element, and at least one kind of second fluorescence in which a part of the emitted light is absorbed by the first phosphor. And the first phosphor is on the side of at least one light emitting element with respect to the second phosphor. In particular, the phosphor layer in this embodiment emits the first phosphor layer 103 that emits light having a peak wavelength of the emission spectrum in the red region and the light having the peak wavelength of the emission spectrum in the yellow to green region. The second phosphor layer 106. The first phosphor layer 103 includes N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, Zr, and Hf. And a nitride-based phosphor activated with at least one element selected from rare earth elements. The second phosphor layer 106 includes Y and Al, and includes at least one element selected from Lu, Sc, La, Gd, Tb, Eu, and Sm, and one selected from Ga and In. And a YAG phosphor activated by at least one element selected from rare earth elements.

  A light-emitting device according to the present invention includes a first recess for mounting a first phosphor and at least one light-emitting element, and the first recess and includes the second phosphor and at least one light-emitting element. And a second recess to be placed. FIG. 1 is a schematic cross-sectional view of a surface-mounted light emitting diode according to the present embodiment. The package 108 is provided with a first recess 101 and a second recess on the light emission observation surface side. Here, the first recess 101 is provided in the second recess 105.

  The second phosphor is on at least one light emitting element and / or on at least one light emitting element different from the at least one light emitting element. That is, as shown in FIG. 1, an LED chip 102 capable of emitting light in the blue region is placed in the first recess 101, and a first phosphor layer 103 is formed so as to cover the LED chip 102. The Further, an LED chip 104 that can emit light in the blue region is placed in the second recess 105, and the second phosphor layer 106 is formed to cover the LED chip 104 and the first phosphor layer 103. It is formed. When a mold member having a diffusing agent is used, the first phosphor layer 103 and the second phosphor layer 106 are covered to protect the conductive wire 110, the LED chip, and the phosphor layer from the external environment. In addition, the light emitted from the phosphor layer can be diffused and mixed in the direction of the emission observation surface. Here, the n-side electrode and the p-side electrode of the LED chip 102 and the LED chip 104 are respectively connected to the negative electrode and the positive electrode of the lead electrode 109 integrally formed in the package 108 using the conductive wire 110.

  In the light emitting diode configured as described above, part of the LED light excites the phosphor contained in the first phosphor layer 103 to generate light in the red region having a wavelength different from that of the LED light. In addition, the LED chip 104 and a part of the LED light from the LED chip 102 excite the phosphor contained in the second phosphor layer 106 to generate light in a green region from a yellow region having a wavelength different from that of the LED light. Let The fluorescence generated from the first phosphor layer 103 and the second phosphor layer 106 and the LED light output without contributing to the excitation of the phosphor are mixed and output from the light emission observation plane direction of the light emitting device. The In this way, a plurality of LED chips can be used, and a plurality of phosphors can be directly excited by each LED chip. Therefore, compared with a conventional light emitting device that excites several kinds of phosphors at a time with one LED chip. Thus, the present invention can provide a light emitting device capable of emitting light with high luminance in the original emission spectrum of each phosphor.

  Thus, when the first phosphor layer and the second phosphor layer are further divided into the third phosphor layer and sequentially laminated, each phosphor layer emits light in a different wavelength region. Can be provided as a light-emitting device with improved color rendering. That is, the peak wavelength of the emission spectrum of the red region emitted from the red phosphor contained in the first phosphor layer is in the range of 600 nm to 700 nm, and the YAG phosphor contained in the second phosphor layer. Since the excitation absorption spectrum has a peak wavelength in the range of 420 nm to 470 nm, light emitted from the red phosphor is hardly absorbed by the YAG phosphor and is efficiently mixed with light of other wavelengths. .

  In addition, the first recess 101 is formed in a portion recessed from the second recess 105. By forming in this way, light having a wavelength of 500 nm to 700 nm that is emitted from the second phosphor layer 106 and travels in the direction of the emission observation surface is reflected by the red phosphor having an excitation absorption spectrum in the wavelength range of 350 nm to 600 nm. Since it is not absorbed, a light emitting device with improved color rendering can be obtained.

  In addition, by forming the phosphor layer in two layers in this way, the light emitted from the first phosphor layer 103 and the LED light pass through the second phosphor layer 106 while phosphor particles Therefore, the light in the blue region, the light in the yellow to green region, and the light in the red region are efficiently mixed. Accordingly, it is possible to improve the color rendering properties of the light emitted from the light emitting device. Further, preferably, the second phosphor layer 106 may contain a diffusing agent or filler, or a mold member containing the diffusing agent or filler may be formed on the second phosphor layer 106. With such a configuration, it is possible to perform color mixing more efficiently.

In general, since the excitation efficiency of a phosphor decreases with increasing ambient temperature, the output of light emitted from the phosphor also decreases. In the present embodiment, when the ambient temperature is changed by 1 ° C. with a phosphor applied to a light emitting element that emits light in the blue region having a peak wavelength λp of about 460 nm, the ratio of decrease in relative light output is emitted. The output reduction rate is assumed. The light emission output decrease rate with respect to the temperature increase of both the red phosphor and the YAG phosphor is 4.0 × 10 ⁻³ [a. u. / ° C.] or less, more preferably 2.0 × 10 ⁻³ [a. u. / ° C.] or less, and a configuration capable of further suppressing the decrease in the luminous flux [lm] of the entire light emitting device that generates heat as compared with the related art. In addition, the red light phosphor and the YAG phosphor can have substantially the same emission output reduction rate with respect to temperature rise. That is, the difference in emission output reduction rate between the red phosphor and the YAG phosphor is 2.0 × 10 ⁻³ [a. u. / ° C.] or less, more preferably 2.0 × 10 ⁻⁴ [a. u. / ° C] or less, the light emission output reduction rate can be made substantially equal. By doing so, the temperature characteristics of the phosphors whose excitation efficiency decreases due to heat generation are substantially the same, and a light emitting device capable of suppressing the occurrence of color misregistration even when the ambient temperature changes can be formed.

Hereafter, each structure of embodiment of this invention is explained in full detail.
[Phosphor]
As the phosphor used in the present invention, various phosphors that are excited by light in the ultraviolet to visible light region and emit light in different wavelength regions can be used in combination. At that time, each of the phosphors in which part of the light emitted from the first phosphor is not absorbed by the second phosphor is selected. In this embodiment, a phosphor that is excited by ultraviolet light and generates light of a predetermined color can be used as a phosphor. As a specific example, for example,
(1) Ca ₁₀ (PO ₄ ) ₆ FCl: Sb, Mn
(2) M ₅ (PO ₄ ) ₃ Cl: Eu (where M is at least one selected from Sr, Ca, Ba, Mg)
(3) BaMg ₂ Al ₁₆ O ₂₇ : Eu
(4) BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn
(5) 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn
(6) Y ₂ O ₂ S: Eu
(7) Mg ₆ As ₂ O ₁₁ : Mn
(8) Sr ₄ Al ₁₄ O ₂₅ : Eu
(9) (Zn, Cd) S: Cu
(10) SrAl ₂ O ₄ : Eu
(11) Ca ₁₀ (PO ₄ ) ₆ ClBr: Mn, Eu
(12) Zn ₂ GeO ₄ : Mn
(13) Gd ₂ O ₂ S: Eu, (14) La ₂ O ₂ S: Eu, and the like.

In particular, the phosphor used in the present embodiment includes an yttrium, aluminum, garnet (garnet type) phosphor, and a red phosphor capable of emitting red light, particularly a nitride phosphor. Combinations can be used. These YAG phosphor and nitride phosphor are separately contained in a phosphor layer composed of a plurality of layers. Hereinafter, each phosphor will be described in detail. Here, in the present invention, the particle size of the phosphor is a value obtained by a volume-based particle size distribution curve, and the volume-based particle size distribution curve can be obtained by measuring the particle size distribution of the phosphor by a laser diffraction / scattering method. Is. Specifically, in an environment where the temperature is 25 ° C. and the humidity is 70%, the phosphor is dispersed in a sodium hexametaphosphate aqueous solution having a concentration of 0.05%, and a laser diffraction particle size distribution analyzer (SALD-2000A) It was obtained by measuring in a particle size range of 0.03 μm to 700 μm.
(Yttrium / Aluminum / Garnet phosphor)
The yttrium / aluminum / garnet-based phosphor (YAG-based phosphor) used in the present embodiment contains Y and Al and is at least one selected from Lu, Sc, La, Gd, Tb, Eu, and Sm. A phosphor that includes one element and one element selected from Ga and In, and is activated by at least one element selected from rare earth elements. It is a phosphor that emits light when excited. In particular, in the present embodiment, two or more kinds of yttrium / aluminum oxide phosphors activated by Ce or Pr and having different compositions are also used. Blue light emitted from a light emitting element using a nitride compound semiconductor in the light emitting layer and green light and red light emitted from a phosphor whose body color is yellow to absorb blue light, or When yellow light and green light and red light are mixedly displayed, a desired white light emission color display can be performed. In order to cause this color mixture, the light-emitting device may contain phosphor powder or bulk in various resins such as epoxy resin, acrylic resin or silicone resin, and translucent inorganic materials such as silicon oxide, aluminum oxide, and silica sol. preferable. Thus, the thing containing the fluorescent substance can be variously used according to uses, such as a dot-like thing and a layer-like thing formed so thinly that the light from the LED chip is transmitted. Arbitrary color tones such as a light bulb color including white can be provided by variously adjusting the ratio, coating, and filling amount of the phosphor and the resin, and selecting the emission wavelength of the light emitting element.

  In addition, by arranging two or more kinds of phosphors in order with respect to the incident light from the light emitting element, a light emitting device capable of efficiently emitting light can be obtained. That is, on the light emitting element having a reflective member, there is a color conversion member containing a phosphor having an absorption wavelength on the long wavelength side and capable of emitting light at the long wavelength side, and an absorption wavelength on the longer wavelength side than that. The reflected light can be effectively used by laminating a color conversion member capable of emitting light at a long wavelength.

When YAG phosphor is used, sufficient light resistance with high efficiency even when it is placed in contact with or close to an LED chip having an irradiance of (Ee) = 0.1 W · cm ^{−2 to} 1000 W · cm ⁻² The light emitting device can be made to have the property.

  The cerium-activated yttrium / aluminum oxide phosphor used in the present embodiment, which is a green-based YAG phosphor capable of emitting light, has a garnet structure and is resistant to heat, light and moisture, and is excited and absorbed. The peak wavelength of the spectrum can be in the vicinity of 420 nm to 470 nm. Also, the emission peak wavelength λp is near 510 nm, and has a broad emission spectrum that extends to the vicinity of 700 nm. On the other hand, the YAG phosphor that emits red light, which is an yttrium-aluminum oxide phosphor activated by cerium, has a garnet structure, is resistant to heat, light and moisture, and has a peak wavelength of 420 nm in the excitation absorption spectrum. To about 470 nm. Further, the emission peak wavelength λp is in the vicinity of 600 nm, and has a broad emission spectrum that extends to the vicinity of 750 nm.

  Of the composition of YAG phosphors with a garnet structure, the emission spectrum is shifted to the short wavelength side by substituting part of Al with Ga, and part of Y of the composition is replaced with Gd and / or La. By doing so, the emission spectrum shifts to the long wavelength side. If the substitution of Y is less than 20%, the green component is large and the red component is small. On the other hand, at 80% or more, although the reddish component increases, the luminance rapidly decreases. Similarly, the excitation absorption spectrum is shifted to the short wavelength side by substituting part of Al with Ga in the composition of the YAG phosphor having a garnet structure. By substituting a part of Gd and / or La, the excitation absorption spectrum is shifted to the longer wavelength side. The peak wavelength of the excitation absorption spectrum of the YAG phosphor is preferably on the shorter wavelength side than the peak wavelength of the emission spectrum of the light emitting element. With this configuration, when the current input to the light emitting element is increased, the peak wavelength of the excitation absorption spectrum substantially matches the peak wavelength of the emission spectrum of the light emitting element, so that the excitation efficiency of the phosphor is not reduced. Thus, a light emitting device in which the occurrence of chromaticity deviation is suppressed can be formed.

  Such phosphors use oxides or compounds that easily become oxides at high temperatures as raw materials for Y, Gd, Ce, La, Al, Sm and Ga, and mix them well in a stoichiometric ratio. And get the raw materials. Alternatively, a coprecipitated oxide obtained by co-precipitation of a solution obtained by coprecipitation of a solution obtained by dissolving a rare earth element of Y, Gd, Ce, La, and Sm in an acid at a stoichiometric ratio with oxalic acid, and aluminum oxide or gallium oxide. To obtain a mixed raw material. An appropriate amount of fluoride such as ammonium fluoride is mixed with this as a flux and packed in a crucible, fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a fired product, and then the fired product in water. It can be obtained by ball milling, washing, separating, drying and finally passing through a sieve. Further, in the method for manufacturing a phosphor according to another embodiment, a first firing step in which a mixture composed of a mixture of phosphor materials and a flux is mixed in the atmosphere or in a weak reducing atmosphere, and in a reducing atmosphere. It is preferable to perform the baking in two stages, which includes the second baking step performed in step (b). Here, the weak reducing atmosphere refers to a weak reducing atmosphere set to include at least the amount of oxygen necessary in the reaction process of forming a desired phosphor from the mixed raw material. By performing the first firing step until the formation of the phosphor structure is completed, blackening of the phosphor can be prevented and a decrease in light absorption efficiency can be prevented. In addition, the reducing atmosphere in the second firing step refers to a reducing atmosphere stronger than the weak reducing atmosphere. By firing in two stages in this way, a phosphor with high absorption efficiency at the excitation wavelength can be obtained. Therefore, when a light emitting device is formed with the phosphor thus formed, the amount of the phosphor necessary for obtaining a desired color tone can be reduced, and a light emitting device with high light extraction efficiency can be formed. Can do.

Yttrium / aluminum oxide phosphors activated with two or more types of cerium having different compositions may be used in combination, or may be arranged independently. When the phosphors are arranged independently, it is preferable to arrange the phosphors in the order of the phosphor that easily absorbs and emits light from the light emitting element on the shorter wavelength side and the phosphor that easily absorbs and emits light on the longer wavelength side. This makes it possible to efficiently absorb and emit light.
(Nitride phosphor)
The first phosphor used in the present invention contains N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, A nitride-based phosphor including at least one element selected from Zr and Hf and activated by at least one element selected from rare earth elements. The nitride-based phosphor used in this embodiment refers to a phosphor that emits light when excited by absorbing visible light and ultraviolet light emitted from an LED chip. In particular, the phosphor according to the present invention includes Mn-added Sr—Ca—Si—N: Eu, Ca—Si—N: Eu, Sr—Si—N: Eu, Sr—Ca—Si—O—N: Eu, Ca—Si—O—N: Eu, Sr—Si—O—N: Eu-based silicone nitride. The basic constituent elements of this phosphor are represented by the general formula L _X Si _Y N _{(2 / 3X + 4 / 3Y)} : Eu or L _X Si _Y O _Z N _{(2 / 3X + 4 / 3Y-2 / 3Z)} : Eu (L is Sr, Ca, or any one of Sr and Ca.) In the general formula, X and Y are preferably X = 2, Y = 5, or X = 1, Y = 7, but any can be used. Specifically, the basic constituent elements, Mn is added _{(Sr X Ca 1-X)} 2 Si 5 N 8: Eu, Sr 2 Si 5 N 8: Eu, Ca 2 Si 5 N 8: Eu, Sr _{X Ca 1-X Si 7 N} 10: Eu, SrSi 7 N 10: Eu, CaSi 7 N 10: it is preferable to use a phosphor represented by Eu, during the composition of the phosphor, Mg, At least one selected from the group consisting of Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr and Ni may be contained. However, the present invention is not limited to this embodiment and examples.
L is any one of Sr, Ca, Sr and Ca. The mixing ratio of Sr and Ca can be changed as desired.
By using Si for the composition of the phosphor, it is possible to provide an inexpensive phosphor with good crystallinity.

Europium Eu, which is a rare earth element, is used for the emission center. Europium mainly has bivalent and trivalent energy levels. The phosphor of the present invention uses Eu ²⁺ as an activator with respect to the base alkaline earth metal silicon nitride. Eu ²⁺ is easily oxidized and is commercially available with a trivalent Eu ₂ O ₃ composition. However, in commercially available Eu ₂ O ₃ , O is greatly involved and it is difficult to obtain a good phosphor. Therefore, it is preferable to use a material obtained by removing O from Eu ₂ O ₃ out of the system. For example, it is preferable to use europium alone or europium nitride. However, this is not the case when Mn is added.

Mn as an additive promotes diffusion of Eu ²⁺ and improves luminous efficiency such as luminous luminance, energy efficiency, and quantum efficiency. Mn is contained in the raw material, or Mn alone or a Mn compound is contained in the manufacturing process and fired together with the raw material. However, Mn is not contained in the basic constituent elements after firing, or even if contained, only a small amount remains compared to the initial content. This is probably because Mn was scattered in the firing step.
The phosphor has at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O and Ni in the basic constituent element or together with the basic constituent element. Contains the above. These elements have actions such as increasing the particle diameter and increasing the luminance of light emission. Further, B, Al, Mg, Cr and Ni have an effect that afterglow can be suppressed.

  Such a nitride-based phosphor absorbs part of the blue light emitted by the LED chip 102 and emits light in the yellow to red region. Using a nitride-based phosphor together with a YAG-based phosphor in the light-emitting device having the above configuration, the blue light emitted by the LED chips 102, 104, the light from the YAG-based phosphor, and the nitride-based phosphor By mixing yellow to red light, a light emitting device that emits warm color mixed light can be obtained. The yttrium / aluminum oxide phosphor activated with cerium absorbs part of the blue light emitted by the LED chip 104 and emits light in the yellow region. Here, the blue light emitted by the LED chip 104 and the yellow light of the yttrium / aluminum oxide fluorescent material emit light blue-white by mixing colors. Therefore, the blue light emitted from the LED chip 102 or the LED chip 104 by containing the phosphor emitting red light and the yttrium aluminum oxide phosphor in the first phosphor layer and the second phosphor layer, respectively. Can be combined to provide a light-emitting device that emits white mixed-color light. Particularly preferred is a white light emitting device whose chromaticity is located on the locus of black body radiation in the chromaticity diagram. However, in order to provide a light emitting device having a desired color temperature, the amount of phosphor of the yttrium / aluminum oxide phosphor and the amount of phosphor of red light emission can be appropriately changed. This light-emitting device that emits white-based mixed color light improves the special color rendering index R9. A conventional light emitting device that emits white light only with a combination of a blue light emitting element and a yttrium aluminum oxide phosphor activated with cerium has a special color rendering index R9 of nearly 0 at a color temperature of Tcp = 4600K, The red component was insufficient. Therefore, increasing the special color rendering index R9 has been a problem to be solved. However, in the present invention, the special color rendering index R9 can be increased by using a phosphor emitting red light together with the yttrium aluminum oxide phosphor.

Next, the phosphor according to the present invention: is described a method of manufacturing the _{((Sr X Ca 1-X} ) 2 Si 5 N 8 Eu), but is not limited to this manufacturing method. The phosphor contains Mn and O.

Raw materials Sr and Ca are pulverized. The raw materials Sr and Ca are preferably used alone, but compounds such as imide compounds and amide compounds can also be used. The raw materials Sr and Ca may contain B, Al, Cu, Mg, Mn, Al ₂ O ₃ or the like. The raw materials Sr and Ca are pulverized in a glove box in an argon atmosphere. Sr and Ca obtained by pulverization preferably have an average particle diameter of about 0.1 μm to 15 μm, but are not limited to this range. The purity of Sr and Ca is preferably 2N or higher, but is not limited thereto. In order to improve the mixed state, at least one of the metal Ca, the metal Sr, and the metal Eu can be alloyed, nitrided, pulverized, and used as a raw material.

The raw material Si is pulverized. The raw material Si is preferably a simple substance, but a nitride compound, an imide compound, an amide compound, or the like can also be used. For example, Si ₃ N ₄ , Si (NH ₂ ) ₂ , Mg ₂ Si, or the like. The purity of the raw material Si is preferably 3N or more, but Al ₂ O ₃ , Mg, metal borides (Co ₃ B, Ni ₃ B, CrB), manganese oxide, H ₃ BO ₃ , B ₂ O ₃ , Compounds such as Cu ₂ O and CuO may be contained. Si is also pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere in the same manner as the raw materials Sr and Ca. The average particle size of the Si compound is preferably about 0.1 μm to 15 μm.

  Next, the raw materials Sr and Ca are nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 1 and formula 2, respectively.

3Sr + N ₂ → Sr ₃ N ₂ (Formula 1)
3Ca + N ₂ → Ca ₃ N ₂ (Formula 2)
Sr and Ca are nitrided in a nitrogen atmosphere at 600 to 900 ° C. for about 5 hours. Sr and Ca may be mixed and nitrided, or may be individually nitrided. Thereby, a nitride of Sr and Ca can be obtained. Sr and Ca nitrides are preferably of high purity, but commercially available ones can also be used.

  The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 3.

3Si + 2N ₂ → Si ₃ N ₄ (Formula 3)
Silicon Si is also nitrided in a nitrogen atmosphere at 800 to 1200 ° C. for about 5 hours. Thereby, silicon nitride is obtained. The silicon nitride used in the present invention is preferably highly pure, but commercially available ones can also be used.

Sr, Ca or Sr—Ca nitride is pulverized. Sr, Ca, and Sr—Ca nitrides are pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere.
Similarly, Si nitride is pulverized. Similarly, the Eu compound Eu ₂ O ₃ is pulverized. Europium oxide is used as the Eu compound, but metal europium, europium nitride, and the like can also be used. In addition, as the raw material Z, an imide compound or an amide compound can be used. Europium oxide is preferably highly purified, but commercially available products can also be used. The average particle size of the alkaline earth metal nitride, silicon nitride and europium oxide after pulverization is preferably about 0.1 μm to 15 μm.

The raw material may contain at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O, and Ni. In addition, the above elements such as Mg, Zn, and B can be mixed by adjusting the blending amount in the following mixing step. These compounds can be added alone to the raw material, but are usually added in the form of compounds. Such compounds include H ₃ BO ₃ , Cu ₂ O ₃ , MgCl ₂ , MgO · CaO, Al ₂ O ₃ , metal borides (CrB, Mg ₃ B ₂ , AlB ₂ , MnB), B ₂ O ₃ , Cu ₂ O, CuO, and the like.

After the pulverization, Sr, Ca, Sr—Ca nitride, Si nitride, and Eu compound Eu ₂ O ₃ are mixed, and Mn is added. Since these mixtures are easily oxidized, they are mixed in a glove box in an Ar atmosphere or a nitrogen atmosphere.

Finally, a mixture of Sr, Ca, Sr—Ca nitride, Si nitride, and Eu compound Eu ₂ O ₃ is fired in an ammonia atmosphere. A phosphor represented by (Sr _X Ca _1-X ) ₂ Si ₅ N ₈ : Eu to which Mn is added can be obtained by firing. The reaction formula of basic constituent elements by this firing is shown below.

ただし、各原料の配合比率を変更することにより、目的とする蛍光体の組成を変更することができる。

However, the composition of the target phosphor can be changed by changing the blending ratio of each raw material.

For firing, a tubular furnace, a small furnace, a high-frequency furnace, a metal furnace, or the like can be used. The firing temperature can be in the range of 1200 to 1700 ° C, but the firing temperature is preferably 1400 to 1700 ° C. It is preferable to use a one-step baking in which the temperature is gradually raised and the baking is performed at 1200 to 1500 ° C. for several hours, but the first baking is performed at 800 to 1000 ° C. and the heating is gradually started from 1200. Two-stage firing (multi-stage firing) in which the second stage firing is performed at 1500 ° C. can also be used. The phosphor material is preferably fired using a boron nitride (BN) crucible or boat. Besides the crucible made of boron nitride, a crucible made of alumina (Al ₂ O ₃ ) can also be used.

  By using the above manufacturing method, it is possible to obtain a target phosphor.

In the embodiment of the present invention, a nitride-based phosphor is used in particular as a phosphor that emits reddish light. In the present invention, a phosphor containing a red-based phosphor other than the nitride-based phosphor is used. The body layer 103 can also be used. Such a phosphor capable of emitting red light is a phosphor that emits light when excited by light having a wavelength of 400 to 600 nm. For example, Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu. CaS: Eu, SrS: Eu, ZnS: Mn, ZnCdS: Ag, Al, ZnCdS: Cu, Al and the like. As described above, the color rendering property of the light emitting device can be improved by combining the phosphor layer containing the YAG phosphor and the phosphor layer containing the phosphor capable of emitting red light.
[LED chips 102 and 104]
Various light sources capable of exciting the first phosphor and the second phosphor can be used as the phosphor excitation light source in the present invention. For example, a semiconductor light emitting device represented by an LED chip, a semiconductor laser device, and the like can be given. Particularly in the present embodiment, the light-emitting elements that are light sources for exciting the first phosphor and the second phosphor are the LED chip 102 and the LED chip 104. Alternatively, as another embodiment of the present invention, there is provided a light source formed by combining a light emitting element capable of emitting ultraviolet light and a phosphor that absorbs the ultraviolet light and emits light having a different wavelength. It does not matter as a light source for exciting the first phosphor and the second phosphor. For example, an LED chip that emits ultraviolet light and a phosphor that absorbs the ultraviolet light and emits light in the blue region are used as an excitation light source, and the first phosphor that emits light in the red region when the excitation light source is excited. In addition, a light emitting device in which the second phosphor that emits light in the green to yellow region when excited by the excitation light source is sequentially arranged from the excitation light source side may be formed. With this configuration, the light emitted from the second phosphor is not absorbed by the first phosphor, so that the light emitting device has improved color rendering using an LED chip that emits ultraviolet light. Can be formed.

As in this embodiment, the first phosphor, the second phosphor, and the light emitting element are combined, and a light emitting device that emits light by mixing the wavelengths of the light converted by exciting the phosphors is used. In this case, an LED chip that emits light having a wavelength capable of exciting the phosphor is used. In the LED chip, a semiconductor such as GaAs, InP, GaAlAs, InGaAlP, InN, AlN, GaN, InGaN, AlGaN, or InGaAlN is formed as a light emitting layer on a substrate by MOCVD or the like. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, a PN junction, etc., a heterostructure, or a double heterostructure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. In addition, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film in which a quantum effect is generated can be used. Preferably, a nitride compound semiconductor (general formula In _i Ga _j Al _k N, where 0 ≦ i, 0 ≦ j, 0 ≦ k, capable of efficiently exciting a phosphor and capable of efficiently emitting a relatively short wavelength) i + j + k = 1).

When a gallium nitride compound semiconductor is used, a material such as sapphire, spinel, SiC, Si, ZnO, or GaN is preferably used for the semiconductor substrate. In order to form gallium nitride with good crystallinity, it is more preferable to use a sapphire substrate. When a semiconductor film is grown on a sapphire substrate, it is preferable to form a gallium nitride semiconductor having a PN junction on a buffer layer made of GaN, AlN or the like. Further, a GaN single crystal itself selectively grown on a sapphire substrate using SiO ₂ as a mask can be used as the substrate. In this case, the light emitting element and the sapphire substrate can be separated by etching away SiO ₂ after forming each semiconductor layer. Gallium nitride-based compound semiconductors exhibit N-type conductivity without being doped with impurities. When forming a desired N-type gallium nitride semiconductor such as improving luminous efficiency, Si, Ge, Se, Te, C, etc. are preferably introduced as appropriate as N-type dopants. On the other hand, when a P-type gallium nitride semiconductor is formed, a P-type dopant such as Zn, Mg, Be, Ca, Sr, or Ba is doped.

  Since a gallium nitride compound semiconductor is difficult to be converted into a P-type simply by doping with a P-type dopant, it is preferable to make it P-type by annealing with heating in a furnace, low-energy electron beam irradiation, plasma irradiation, etc. after introduction of the P-type dopant. . Specific examples of the layer structure of the light-emitting element include an N-type contact layer, which is a gallium nitride semiconductor, and an aluminum nitride / gallium semiconductor on a sapphire substrate or silicon carbide having a buffer layer in which gallium nitride, aluminum nitride, or the like is formed at a low temperature. An N-type cladding layer, an active layer that is an indium gallium nitride semiconductor doped with Zn and Si, a P-type cladding layer that is an aluminum nitride-gallium semiconductor, and a P-type contact layer that is a gallium nitride semiconductor Are preferable. In order to form the LED chip 102, in the case of the LED chip 102 having a sapphire substrate, an exposed surface of a P-type semiconductor and an N-type semiconductor is formed by etching or the like, and then a sputtering method or a vacuum evaporation method is performed on the semiconductor layer. Each electrode is formed in a desired shape. In the case of a SiC substrate, a pair of electrodes can be formed using the conductivity of the substrate itself.

  Next, the formed semiconductor wafer or the like is directly fully cut by a dicing saw with a blade having a diamond cutting edge, or a groove having a width wider than the cutting edge width is cut (half cut), and then the semiconductor is applied by an external force. Break the wafer. Alternatively, after a very thin scribe line (meridian) is drawn on the semiconductor wafer by, for example, a grid shape by a scriber in which the diamond needle at the tip moves reciprocally linearly, the wafer is divided by an external force and cut into chips. In this way, the LED chip 102 which is a nitride compound semiconductor can be formed.

  In the light emitting device of the present invention that excites the phosphor to emit light, the emission peak wavelength of the LED chip can be 350 nm or more and 530 nm or less in consideration of the excitation absorption wavelength of the phosphor.

Further, it is possible to individually control the light emission outputs of the LED chip 102 and the LED chip 104, and to control the degree of color mixture of light emitted after wavelength conversion by the first phosphor and the second phosphor. Thus, a light emitting device capable of freely adjusting the color temperature of the mixed color light can be obtained.
[Conductive wire 110]
The conductive wire 110 is required to have good ohmic properties with the electrodes of the LED chip, mechanical connectivity, electrical conductivity, and thermal conductivity. Preferably ^{0.01cal / (s) (cm 2} ) (℃ / cm) or higher as heat conductivity, and more preferably ^{0.5cal / (s) (cm 2} ) (℃ / cm) or more. In consideration of workability and the like, the diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less. In particular, the conductive wire is likely to break at the interface between the coating portion containing the phosphor and the mold member not containing the phosphor. Even if the same material is used, it is considered that wire breakage easily occurs because the substantial amount of thermal expansion differs depending on the phosphor. Therefore, the diameter of the conductive wire is more preferably 25 μm or more, and more preferably 35 μm or less from the viewpoint of light emission area and ease of handling.

Specific examples of such conductive wires include conductive wires using metals such as gold, copper, platinum, and aluminum, and alloys thereof. Such a conductive wire can easily connect the electrode of each LED chip to the inner lead, the mount lead, and the like by a wire bonding device.
[Package 108]
The package 108 in the present embodiment includes a first recess 101 on which the LED chip 102 and the first phosphor layer 103 are placed, and the first recess, and the LED 104 and the second phosphor layer 106 are placed on the package 108. A second recess. In addition, a pair of positive and negative lead electrodes 109 for supplying power to the LED chip are integrally formed in a part of the package. As shown in FIG. 1, the first recess 101 is preferably formed so as to be recessed in the direction opposite to the emission observation surface from the bottom surface of the second recess 105 on which the LED chip 104 is placed. Alternatively, a cup-shaped first recess may be provided on the same bottom surface on which the LED chip 104 is placed in the second recess 105. In another embodiment, the LED chip 104 is mounted on the same surface on which the LED chip 102 is mounted via a spacer, and the LED chip 102 is recessed from the LED chip 104 by the thickness of the spacer. You may make it mount in the position near. In still another embodiment, the first phosphor layer 103 is formed on the light emission observation surface side surface of the LED chip 102 by a screen printing or coating method using spraying, and then placed on the bottom surface of the recess. It doesn't matter. By doing so, it is possible to reliably cover only the desired LED chip 102 with the phosphor layer forming material containing the red phosphor. In addition, light emitted from the phosphor included in the second phosphor layer 106 and traveling in the direction of the emission observation surface is not absorbed by the red phosphor included in the first phosphor layer, thereby improving color rendering. It is possible to obtain a light emitting device.

  Such a package 108 can be formed relatively easily by transfer molding, insert molding, or the like. Aromatic nylon resin, polyphthalamide resin (PPA), sulfone resin, polyamideimide resin (PAI), polyketone resin (PK), polycarbonate resin, polyphenylene sulfide (PPS), liquid crystal polymer (LCP) ), Thermoplastic resins such as ABS resin and PBT resin can be used. In addition, you may use what made these thermoplastic resins contain glass fiber as a thermoplastic material. By containing glass fibers in this way, it is possible to form a package having high rigidity and high strength. Here, the first concave portion and the second concave portion can be formed by integral molding at the time of package molding using a molding die.

  The package can also be formed using a metal material. In this case, the concave portion can be easily formed by applying a pressing process, and the lead electrode is formed on a part of the package via an insulating member. By using a metal material as a package material in this manner, a light emitting device with improved heat dissipation can be obtained.

Adhesion of the LED chip into the package recess can be performed by an insulating adhesive such as a thermosetting resin. Specifically, an epoxy resin, an acrylic resin, an imide resin, etc. are mentioned. Further, Ag paste, carbon paste, metal bumps, eutectic solder, etc. are used in order to achieve electrical continuity with the lead electrode from the face down which is a mounting method in which the electrode surface of the LED chip is connected to face the lead electrode. be able to. Further, in order to improve the light utilization efficiency of the light emitting diode, the surface of the mount lead on which the LED chip is arranged may be a mirror surface, and the surface may have a reflection function. In this case, the surface roughness is preferably 0.1 S or more and 0.8 S or less.
[Lead electrode 109]
The pair of positive and negative lead electrodes used in the present embodiment supplies power to the LED chip, and is formed on a part of the package 108 through an insulating member as necessary. As another embodiment, the first concave portion and the second concave portion may be provided directly on one of the positive and negative lead electrodes, and the LED chip may be placed via an insulating adhesive. The specific electric resistance of the lead electrode is preferably 300 μΩ-cm or less, more preferably 3 μΩ-cm or less. Further, when a plurality of LED chips are stacked on the lead electrode, it is required that the heat conductivity is good because the amount of heat generated from the LED chips increases. Specifically, more preferably preferably ^{0.01cal / (s) (cm 2} ) (℃ / cm) or more is ^{0.5cal / (s) (cm 2} ) (℃ / cm) or more. Examples of materials that satisfy these conditions include iron, copper, iron-containing copper, tin-containing copper, and ceramic with a metallized pattern.
[Mount lead 202]
As shown in FIG. 3, the mount lead 202 in the present embodiment includes the LED chip 102 and the first recess 101 and the second recess 105 in which the LED chip is disposed, and is mounted by a die bond device or the like. It should be large enough to do. As shown in FIG. 3, the first recess 101 is preferably formed so as to be recessed in the direction opposite to the emission observation surface from the bottom surface of the second recess 105 on which the LED chip 104 is placed. Alternatively, a cup-shaped first recess may be provided on the same bottom surface on which the LED chip 104 is placed in the second recess 105. In another embodiment, the LED chip 104 is placed on the same surface on which the LED chip 102 is placed via a spacer, and the LED chip 102 is recessed from the LED chip 104 by the thickness of the spacer. You may make it mount in the position near. In still another embodiment, the first phosphor layer 103 is formed on the light emission observation surface side surface of the LED chip 102 by a screen printing or coating method using spraying, and then placed on the bottom surface of the recess. It doesn't matter. By doing so, it is possible to reliably cover only the desired LED chip 102 with the phosphor layer forming material containing the red phosphor. In addition, when a plurality of LED chips are installed and the mount lead is used as a common electrode of the LED chip, sufficient electrical conductivity and connectivity with a bonding wire or the like are required.

The adhesion between the LED chips 102 and 104 and the cup of the mount lead 202 can be performed by a thermosetting resin or the like. Specifically, an epoxy resin, an acrylic resin, an imide resin, etc. are mentioned. In addition, Ag paste, carbon paste, metal bumps, or the like can be used for bonding and electrical connection with the mount lead using a face-down LED chip or the like. Further, in order to improve the light utilization efficiency of the light emitting diode, the surface of the mount lead on which the LED chip is arranged may be a mirror surface, and the surface may have a reflection function. In this case, the surface roughness is preferably 0.1 S or more and 0.8 S or less. The specific electric resistance of the mount lead is preferably 300 μΩ-cm or less, more preferably 3 μΩ-cm or less. In addition, when a plurality of LED chips are stacked on the mount lead, the heat generation from the LED chip increases, so that the thermal conductivity is required to be good. Specifically, more preferably preferably ^{0.01cal / (s) (cm 2} ) (℃ / cm) or more is ^{0.5cal / (s) (cm 2} ) (℃ / cm) or more. Examples of materials that satisfy these conditions include iron, copper, iron-containing copper, tin-containing copper, and ceramic with a metallized pattern. When such a metal is used, the first recess and the second recess can be formed by processing using a molding die, pressing processing, or the like.
[Inner lead 201]
The inner lead 201 is intended to be connected to the conductive wire 110 connected to the LED chip 102 disposed on the mount lead 202. When a plurality of LED chips are provided on the mount lead, it is necessary to be able to arrange the conductive wires so that they are not in contact with each other. Specifically, as the distance from the mount lead increases, the area of the end surface of the inner lead that is wire-bonded increases to prevent contact of the conductive wire that is connected to the inner lead that is further away from the mount lead. it can. The roughness of the connecting end surface with the conductive wire is preferably 1.6 S or more and 10 S or less in consideration of adhesion. In order to form the tip of the inner lead in various shapes, the shape of the lead frame may be determined in advance by the mold, and it may be punched or formed, or after all the inner leads are formed, the upper part of the inner lead You may form by shaving a part of. Furthermore, after punching and forming the inner lead, it is possible to simultaneously form the desired end face area and end face height by applying pressure from the end face direction.

The inner lead is required to have good connectivity and electrical conductivity with a bonding wire or the like that is a conductive wire. The specific electric resistance is preferably 300 μΩ-cm or less, more preferably 3 μΩ-cm or less. Examples of materials that satisfy these conditions include iron, copper, iron-containing copper, tin-containing copper and copper, gold, silver plated aluminum, iron, copper, and the like.
[Phosphor layers 103 and 106]
The first phosphor layer 103 and the second phosphor layer 106 in the present embodiment cover the LED chip in a recess provided in the package and convert red light emission of the LED chip. And a YAG phosphor. As a specific material for forming the phosphor layer, a transparent resin having excellent weather resistance such as epoxy resin, urea resin, and silicone resin, and a light-transmitting inorganic material such as silica sol and glass having excellent light resistance are preferably used. It is done. Moreover, you may contain a diffusing agent with fluorescent substance. As specific diffusing agents, barium titanate, titanium oxide, aluminum oxide, silicon oxide, calcium carbonate, silicon dioxide and the like are preferably used.
[Mold member 107]
The mold member 107 can be provided to protect the LED chips 102 and 104, the conductive wire 110, the phosphor layer containing the phosphor, and the like from the external environment according to the use application of the light emitting diode. In general, the mold member 107 can be formed using a resin. Moreover, although a viewing angle can be increased by containing fluorescent substance, the directivity from an LED chip can be eased and the viewing angle can be further increased by adding a diffusing agent to the resin mold. Furthermore, by forming the mold member 107 in a desired shape, it is possible to provide a lens effect that focuses or diffuses light emitted from the LED chip. Accordingly, a plurality of mold members 107 may be stacked. Specifically, a convex lens shape, a concave lens shape, an elliptical shape as viewed from the light emission observation surface, or a combination of them. As a specific material of the mold member 107, a transparent resin having excellent weather resistance such as epoxy resin, urea resin, and silicone resin, and a light-transmitting inorganic material such as silica sol and glass having excellent light resistance are preferably used. . As the diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide, calcium carbonate, silicon dioxide, or the like is preferably used. In consideration of the refractive index, the mold member and the phosphor layer may be formed using the same member, for example, a silicone resin. In the present invention, adding a diffusing agent or a coloring agent to the mold member can hide the coloring of the phosphor viewed from the light emission observation surface side. In addition, the coloring of the phosphor means that the phosphor of the present invention emits light by absorbing the blue component of the strong external light. Therefore, it seems to be colored yellow. In particular, depending on the shape of the mold member such as a convex lens shape, the colored portion may appear enlarged. Such coloring may be undesirable in terms of design. The diffusing agent contained in the mold member can make the mold member invisible white by coloring the mold member milky white and the colorant in a desired color. Therefore, the color of the phosphor is not observed from such a light emission observation surface side.

  Moreover, when the main light emission wavelength of the light emitted from the LED chip is 430 nm or more, it is more preferable in terms of weather resistance to contain an ultraviolet absorber as a light stabilizer in the mold member.

Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.
Example 1
FIG. 1 shows a schematic diagram of a light emitting diode 100 formed in this embodiment. In this example, the nitride-based phosphor contained in the first phosphor layer 103 is (Sr _0.7 Ca _0.3 ) ₂ Si ₅ N ₈ : Eu (hereinafter referred to as “phosphor 1”). ). FIG. 11 shows an excitation absorption spectrum of the phosphor, and FIG. 12 shows an emission spectrum. The YAG-based phosphor contained in the second phosphor layer 106 is Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce (hereinafter referred to as “phosphor 2”). FIG. 9 shows an excitation absorption spectrum of the phosphor, and FIG. 10 shows an emission spectrum.

  As shown in FIG. 1, a package 108 having a first recess 101, a second recess 105, and a pair of positive and negative lead electrodes 109 is formed by injection molding using a thermoplastic resin as a material. The LED chips 102 and 104 capable of emitting light in the blue region are bonded and fixed in the first recess and the second recess, respectively, with an insulating adhesive. In this embodiment, one LED chip is placed in each recess, but a plurality of chips may be placed in each recess. By mounting a plurality of LED chips in this way, the phosphors in the respective recesses can be directly excited, so that a light emitting device capable of emitting light with high luminance can be formed. The positive and negative electrodes of the LED chips 102 and 104 are wire-bonded to the positive and negative electrodes of the lead electrode using the conductive wire 110, respectively.

  The material for forming the first phosphor layer 103 containing the phosphor 1 in the silicone resin is adjusted, and the prepared material is arranged so that the LED chip 102 placed in the first recess is covered. Harden. Here, the blending ratio of the silicone resin and the phosphor 1 is (silicone resin) :( phosphor 1) = 10: 3 (weight ratio).

  Subsequently, a material for forming the second phosphor layer 106 in which the phosphor 2 is contained in the silicone resin is prepared, and the LED chip 104 and the first phosphor layer 103 placed in the second recess. Place and cure the prepared material so that it is covered. Here, the compounding ratio of the silicone resin and the phosphor 2 is (silicone resin) :( phosphor 2) = 10: 1 (weight ratio).

  The conductive wire 109, the phosphor layer, and the LED chip are sealed with a mold member 107 containing a diffusing agent in a silicone resin.

  When a current is passed through the light emitting device formed as described above, mixed color light having an emission spectrum as shown in FIG. 6 can be obtained, and color rendering can be improved and high output light emission can be achieved as compared with the prior art. Here, the output of the LED chip 102 is preferably larger than the output of the LED chip 104. By doing so, color rendering properties can be further improved and high-output light emission can be achieved. Table 1 below shows the measurement results of the optical characteristics when the light emitting diode is formed in this example.

本発明に係る発光装置と、該発光装置から出光した光を発光観測面側に導く導光板とを組み合わせ、液晶ディスプレイの構成部材として使用可能なバックライト光源を形成した場合、周囲温度の変化によらず演色性を向上させ、かつ色度ズレが殆ど生じないバックライト光源とすることが可能である。
（実施例２）
図２に本実施例において形成される発光ダイオード２００の模式図を示す。本実施例においては、上記実施例のように第１の凹部および第２の凹部とすることなく設けられた凹部１０１に少なくとも一つのＬＥＤチップ１０２を載置し、実施例１と同様の方法により、ＬＥＤチップ１０２の上に第１の蛍光体層および第２の蛍光体層を順に積層させる。このように構成することにより従来技術と比較して演色性を向上させた発光装置とすることができる。
（実施例３）
本実施例において、第１の蛍光体層１０３および第２の蛍光体層１０６に含有される蛍光体は、上記実施例と同様に、それぞれ蛍光体１および蛍光体２である。ただし、蛍光体１および蛍光体２の含有量は、それぞれ上記実施例における含有量より多い。第１の蛍光体層および第２の蛍光体層は上記実施例と同様の方法により形成される。

When a light source according to the present invention and a light guide plate that guides light emitted from the light emitting device to the light emission observation surface are combined to form a backlight light source that can be used as a component of a liquid crystal display, the ambient temperature changes. Therefore, it is possible to provide a backlight light source that improves color rendering and hardly causes chromaticity deviation.
(Example 2)
FIG. 2 shows a schematic diagram of a light emitting diode 200 formed in this embodiment. In this embodiment, at least one LED chip 102 is placed in the recess 101 provided without the first recess and the second recess as in the above embodiment, and the same method as in the first embodiment is used. The first phosphor layer and the second phosphor layer are sequentially stacked on the LED chip 102. With this configuration, it is possible to obtain a light emitting device with improved color rendering as compared with the prior art.
(Example 3)
In the present embodiment, the phosphors contained in the first phosphor layer 103 and the second phosphor layer 106 are the phosphor 1 and the phosphor 2, respectively, as in the above embodiment. However, the contents of the phosphor 1 and the phosphor 2 are respectively greater than the contents in the above examples. The first phosphor layer and the second phosphor layer are formed by the same method as in the above embodiment.

  FIG. 3 shows a schematic diagram of a light emitting diode 300 formed in this embodiment. The light emitting diode 300 is a lead type light emitting diode including a mount lead 202 and an inner lead 201, and a first recess 101 and a second recess 105 are provided in a cup portion of the mount lead 202. An LED chip 102 is provided on the bottom surface of the first recess, and a first phosphor layer 103 is formed so as to cover the LED chip 102. Further, the LED chip 104 is provided on the bottom surface of the second recess, and the second phosphor layer 106 is formed so as to cover the LED chip 104 and the first phosphor layer 103. Further, the phosphor layer, the lead electrode, and the conductive wire are resin molded by the mold member 107 and configured. Here, the n-side electrode and the p-side electrode of the LED chips 102 and 104 are connected to the mount lead 202 and the inner lead 201 using the wire 110, respectively.

  By passing an electric current through the formed light emitting device, a reddish mixed color light having an emission spectrum as shown in FIG. 6 was obtained, and the color rendering was improved as compared with the prior art. The measurement results of the optical characteristics when the light emitting diode is formed in this example are shown in Table 2 below.

（実施例４）
図４に本実施例において形成される発光ダイオード４００の模式図を示す。本実施例においては、実施例３と同様にマウント・リード電極に対して形成された凹部１０１に少なくとも一つのＬＥＤチップ１０２を載置する。上述した他の実施例と同様の方法により、ＬＥＤチップ１０２の上に第１の蛍光体層および第２の蛍光体層を順に積層させる。このように構成することにより従来技術と比較して演色性を向上させた発光装置とすることができる。
（実施例５）
図５に本実施例において形成される発光ダイオード５００の模式図を示す。他の実施例と同様に、第１の蛍光体層１０３により被覆されたＬＥＤチップ１０２が載置される第１の凹部１０１、および第２の蛍光体層１０６により被覆されたＬＥＤチップ１０４が載置される第２の凹部１０５を設ける。ただし、本実施例において形成される発光ダイオード５００は、正負一対のリード電極１０９をＬＥＤチップ１０２、１０４に対してそれぞれ一対設け、ＬＥＤチップ１０２、１０４のそれぞれについて電流を投入し、独立して発光出力の制御を可能としてある。

(Example 4)
FIG. 4 shows a schematic diagram of a light emitting diode 400 formed in this embodiment. In this embodiment, as in the third embodiment, at least one LED chip 102 is placed in the recess 101 formed on the mount / lead electrode. A first phosphor layer and a second phosphor layer are sequentially laminated on the LED chip 102 by the same method as in the other embodiments described above. With this configuration, it is possible to obtain a light emitting device with improved color rendering as compared with the prior art.
(Example 5)
FIG. 5 shows a schematic diagram of a light emitting diode 500 formed in this embodiment. Similar to the other embodiments, the first recess 101 on which the LED chip 102 covered with the first phosphor layer 103 is placed and the LED chip 104 covered with the second phosphor layer 106 are placed. A second recess 105 is provided. However, the light-emitting diode 500 formed in this embodiment is provided with a pair of positive and negative lead electrodes 109 for the LED chips 102 and 104, and a current is supplied to each of the LED chips 102 and 104 to independently emit light. The output can be controlled.

In this way, by controlling the degree of color mixing of light emitted after being wavelength-converted by the first phosphor and the second phosphor, a light emitting device capable of freely adjusting the color temperature of the mixed color light can be obtained. .
(Example 6)
FIG. 1 shows a schematic diagram of a light emitting diode 100 formed in this embodiment. In this example, the nitride-based phosphor contained in the first phosphor layer 103 is (Sr _0.7 Ca _0.3 ) ₂ Si ₅ N ₈ : Eu (hereinafter referred to as “phosphor 1”). ). The YAG-based phosphor contained in the second phosphor layer 106 is Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce (hereinafter referred to as “phosphor 2”).

  As shown in FIG. 1, a package 108 having a first recess 101, a second recess 105, and a pair of positive and negative lead electrodes 109 is formed by injection molding using a thermoplastic resin as a material. The LED chips 102 and 104 capable of emitting light in the blue region are bonded and fixed in the first recess and the second recess, respectively, with an insulating adhesive. In this embodiment, one LED chip is placed in each recess, but a plurality of chips may be placed in each recess. By mounting a plurality of LED chips in this way, the phosphors in the respective recesses can be directly excited, so that a light emitting device capable of emitting light with high luminance can be formed. The positive and negative electrodes of the LED chips 102 and 104 are wire-bonded to the positive and negative electrodes of the lead electrode using the conductive wire 110, respectively.

FIG. 9 shows the excitation absorption spectrum of the YAG phosphor used in this example. FIG. 10 shows an emission spectrum of the YAG phosphor used in this example. In this example, Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce (phosphor 2) and (Y _0.8 Gd _0.2 ) ₃ Al are used as YAG phosphors having different compositions. ₅ O ₁₂ : Ce (hereinafter referred to as “phosphor 3”) and Y ₃ Al ₅ O ₁₂ : Ce (hereinafter referred to as “phosphor 4”) were used. These phosphors are phosphors that are excited by absorbing blue light from the LED chip and emit yellow to green light, and are contained in the second phosphor layer.

FIG. 11 shows the excitation absorption spectrum of the nitride phosphor used in this example. FIG. 12 shows the emission spectrum of the nitride phosphor used in this example. In this example, as nitride phosphors having different compositions, (Sr _0.7 Ca _0.3 ) ₂ Si ₅ N ₈ : Eu (phosphor 1), Ca ₂ Si ₅ N ₈ : Eu (hereinafter “ Phosphor 5 ”) was used. These phosphors are phosphors that are excited by absorbing blue light from the LED chip and emit red light, and are contained in the first phosphor layer. The composition of the phosphor used in this example, the peak wavelength of the emission spectrum, and the color tone are shown below.

まず、蛍光体１から蛍光体５を１種類ずつ使用して発光ダイオードを形成した後、２０ｍＡのパルス電流を加えることによりＬＥＤチップ自体の発熱が無視できる条件下にて周囲温度を上昇させ、周囲温度に対する発光ダイオードの発光出力を測定した。次に、蛍光体１から蛍光体５のそれぞれについて、２５℃を基準とするＬＥＤ発光の相対出力を求め、周囲温度−相対光出力特性として図１４から図１８に示した。また、発光ダイオードの周囲温度を１℃変化させたときＬＥＤ発光相対出力の低下率を各蛍光体について求め、周囲温度の上昇に対する発光出力低下率として以下の表４に示す。

First, after forming a light emitting diode by using phosphors 1 to 5 one by one, a 20 mA pulse current is applied to raise the ambient temperature under conditions where the heat generation of the LED chip itself can be ignored, The light emission output of the light emitting diode with respect to temperature was measured. Next, with respect to each of the phosphors 1 to 5, the relative output of the LED light emission based on 25 ° C. was obtained, and the ambient temperature-relative light output characteristics are shown in FIG. 14 to FIG. Further, when the ambient temperature of the light emitting diode is changed by 1 ° C., the LED light emission relative output reduction rate is obtained for each phosphor, and the light emission output reduction rate with respect to the increase in ambient temperature is shown in Table 4 below.

本実施例において使用される蛍光体は、温度上昇に対する発光出力低下率がほぼ等しい蛍光体１と蛍光体２である。即ち、組み合わせる蛍光体の周囲温度に対する発光出力低下率が共に２．０×１０^−３［ａ．ｕ．／℃］以下と他の蛍光体の組み合わせと比較して小さく、かつ発光出力低下率の差が２．０×１０^−４［ａ．ｕ．／℃］と、他の蛍光体の組み合わせと比較して小さい組み合わせとしたものである。

The phosphors used in this example are phosphor 1 and phosphor 2 that have substantially the same emission output reduction rate with respect to temperature rise. That is, the emission output decrease rate with respect to the ambient temperature of the phosphors to be combined is 2.0 × 10 ⁻³ [a. u. / ° C.] and smaller than the combination of other phosphors, and the difference in the light output reduction rate is 2.0 × 10 ⁻⁴ [a. u. / ° C.] and a smaller combination than other phosphor combinations.

The LED chip 102 or 104 used for exciting the phosphor in this embodiment is a light emitting element in which an InGaAlN compound semiconductor is formed as a light emitting layer, and the peak wavelength of the emission spectrum is around 460 nm. Further, by increasing the current density between ³ to 300 A / cm ² , the chromaticity coordinates are shifted to the low color temperature side along the black body radiation locus. FIG. 8 is a diagram showing the current characteristics of the emission spectrum when the current flowing through the LED chips 102 and 104 is changed. As shown in FIG. 8, in the current characteristics of the emission spectrum, the peak wavelength shifts to the short wavelength side as the input current is increased.

  Therefore, as shown in FIG. 9, the peak of the excitation absorption spectrum of the three phosphors 2, 3, 4 is located at the position where the peak wavelength of the emission spectrum of the LED chip is shifted due to the increase of the current input to the LED chip. The positions of the wavelengths are almost matched. Here, the difference between the peak wavelength of the excitation absorption spectrum of the phosphors 2, 3, and 4 and the peak wavelength of the emission spectrum of the LED chip is preferably 40 nm or less. By using such a phosphor, the excitation efficiency of the phosphor is improved, and the amount of light emitted from the LED without being wavelength-converted is reduced, thereby preventing the chromaticity deviation of the light emitting device. Can do.

  Here, when the phosphor 2 is used, the emission spectrum of the phosphor 2 moves to a shorter wavelength side than the emission spectra of the other phosphors as shown in FIG. Therefore, although the chromaticity deviation of the light emitting device can be prevented by shifting the peak position of the excitation absorption spectrum of the YAG-based phosphor, the light emission of the light emitting device deviates from the black body radiation locus. Is added to the mixed color light to adjust the chromaticity coordinates near the black body radiation locus.

  As shown in Table 1, the color rendering property in this example is Ra = 91.9, which can improve the color rendering property as compared with the prior art.

FIG. 13 is a diagram illustrating changes in chromaticity when the light emitting device formed in this example is DC driven. When the current density is increased from 15 [A / cm ² ] to 180 [A / cm ² ], the change in the chromaticity of light due to the color mixture shows that the X coordinate is 0.339 to 0.3 on the chromaticity diagram. 351, the Y coordinate is in the range of 0.321 to 0.322. That is, the chromaticity of the light due to the color mixture moves at a position substantially along the black body radiation locus even when the current is increased, and the chromaticity hardly changes.

In the configuration of this example, the emission output decrease rate with respect to the ambient temperature of the phosphors to be combined is 2.0 × 10 ⁻³ [a. u. / ° C.] and less than the phosphors of the other examples, and the difference in the light output reduction rate is 2.0 × 10 ⁻⁴ [a. u. / ° C.] and a smaller combination than the other examples. That is, the light emission output reduction rate with respect to the temperature rise of the phosphor 1 and the phosphor 2 is substantially equal. With this configuration, even if the light emission outputs of the phosphor 1 and the phosphor 2 are decreased due to an increase in the ambient temperature due to heat generation of the light emitting element, the light emission output difference between the phosphor 1 and the phosphor 2. Are kept almost the same without being affected by the ambient temperature. That is, by adopting the configuration of this embodiment, it is possible to improve the color rendering property regardless of the change in the ambient temperature of the light emitting device and to obtain a light emitting device that hardly causes chromaticity deviation.

  In addition, when the light emitting device according to the present invention and a light guide plate that guides the light emitted from the light emitting device to the light emission observation surface side are combined to form a backlight light source that can be used as a constituent member of a liquid crystal display, It is possible to improve a color rendering property regardless of a change and to provide a backlight light source that hardly causes chromaticity deviation.

  The light emitting device of the present invention includes a fluorescent display tube, a display, a PDP, a CRT, FL, a FED, a projection tube, etc., in particular, a blue light emitting diode or an ultraviolet light emitting diode, and a blue light emitting diode or an ultraviolet light emitting diode and a predetermined phosphor. The present invention relates to a phosphor used in a white light-emitting device and the like that is extremely excellent in light emission characteristics using a light source formed in combination as an excitation light source. In addition, the light emitting device having the phosphor according to the present invention can be used for fluorescent lamps for store front lighting, medical spot lighting, etc., as well as backlight light sources for liquid crystal displays, light sources for projectors, and light emission. It can also be applied to the field of diodes (LEDs).

It is typical sectional drawing of the light emitting diode which concerns on this invention. It is typical sectional drawing of the light emitting diode which concerns on this invention. It is typical sectional drawing of the light emitting diode which concerns on this invention. It is typical sectional drawing of the light emitting diode which concerns on this invention. It is the typical front view (a) and sectional drawing (b) of the light emitting diode which concern on this invention. It is a figure which shows the emission spectrum characteristic of the light-emitting device in this invention. It is a figure which shows the emission spectrum characteristic of the light-emitting device of the prior art shown for a comparison with this invention. It is a figure which shows the emission spectrum characteristic of the LED chip in this invention. It is a figure which shows the excitation absorption spectrum of the YAG type fluorescent substance in this invention. It is a figure which shows the emission spectrum of the YAG type fluorescent substance in this invention. It is a figure which shows the excitation absorption spectrum of the nitride type fluorescent substance in this invention. It is a figure which shows the emission spectrum of the nitride type fluorescent substance in this invention. It is a figure which shows the current-chromaticity characteristic (measurement by DC drive) in this invention. It is a figure which shows the ambient temperature-relative light output characteristic of the light emitting diode which uses the fluorescent substance 1 in this invention. It is a figure which shows the ambient temperature-relative light output characteristic of the light emitting diode which uses the fluorescent substance 2 in this invention. It is a figure which shows the ambient temperature-relative light output characteristic of the light emitting diode which uses the fluorescent substance 3 in this invention. It is a figure which shows the ambient temperature-relative light output characteristic of the light emitting diode which uses the fluorescent substance 4 in this invention. It is a figure which shows the ambient temperature-relative light output characteristic of the light emitting diode which uses the fluorescent substance 5 in this invention.

Explanation of symbols

100, 200... Surface mount type light emitting diodes 300, 400... Light emitting diode 101... First recess 102, 104... LED chip 103. Two recesses 106 ... second phosphor layer 107 ... mold member 108 ... package 109 ... lead electrode 110 ... conductive wire 201 ... inner lead 202 ... mount Lead

Claims (8)

A light source;
A plurality of phosphor layers that absorb at least part of the light from the light source and emit light having different wavelengths; and
A light emitting device comprising: a package in which the light source is disposed;
The light source has a first light source and a second light source,
The package is provided with a step, has a second recess on which the second light source is placed, and is in the second recess, and is opposite to the emission observation surface from the bottom surface of the second recess. And a first recess in which the first light source is placed, and
The phosphor layer may include a first phosphor layer and second phosphor layer,
The first phosphor layer is disposed in the first recess, absorbs at least a part of light from the first light source, and has a first wavelength longer than that of the light from the first light source . Emit light,
The second phosphor layer absorbs light from the second light source and at least part of light from the first light source, and has a longer wavelength than the light from the second light source. A second light of
The peak wavelength of the first light is longer than the peak wavelength of the second light,
The light emitting device, wherein the first light from the first phosphor is diffused without being absorbed by the second phosphor. A light source;
A plurality of phosphor layers that absorb at least part of the light from the light source and emit light having different wavelengths; and
A light emitting device comprising: a package in which the light source is disposed;
Each of the light sources includes a first light source and a second light source capable of emitting light in a blue region,
The package is provided with a step, has a second recess on which the second light source is placed, and is in the second recess, and is opposite to the emission observation surface from the bottom surface of the second recess. And a first recess in which the first light source is placed, and
The phosphor layer includes a first phosphor layer and a second phosphor layer ,
The first phosphor layer is disposed in the first recess, absorbs at least a part of light from the first light source, and emits first light having a peak wavelength of an emission spectrum in a red region. And
The second phosphor layer absorbs light from the second light source and at least part of light from the first light source, and has a peak wavelength of an emission spectrum in a yellow to green region. Emits a second light,
The light emitting device, wherein the first light from the first phosphor is diffused without being absorbed by the second phosphor. The first phosphor layer includes N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn; and C, Si, Ge, Sn, Ti, Zr, and Hf 3. The light emitting device according to claim 1, further comprising a nitride-based phosphor activated by at least one element selected from rare earth elements. The second phosphor layer includes Y and Al, and at least one element selected from Lu, Sc, La, Gd, Tb, Eu and Sm, and one element selected from Ga and In. The light-emitting device according to claim 1, further comprising: an yttrium-aluminum-garnet-based phosphor activated by at least one element selected from rare earth elements. The light emitting device according to claim 1, wherein the light source is a semiconductor light emitting element. 3. The light source according to claim 1, wherein at least one of the light sources is formed by combining a light emitting element that emits ultraviolet rays and a phosphor that absorbs the ultraviolet rays and emits light having different wavelengths. The light emitting device described. The first phosphor layer includes N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn; and C, Si, Ge, Sn, Ti, Zr, and Hf A nitride-based phosphor activated with at least one element selected from rare earth elements, and at least one element selected from
The second phosphor layer includes Y and Al, and at least one element selected from Lu, Sc, La, Gd, Tb, Eu and Sm, and one element selected from Ga and In. An yttrium-aluminum-garnet phosphor activated by at least one element selected from rare earth elements,
The difference between the light emission output reduction rate of the nitride-based phosphor and the light emission output reduction rate of the yttrium / aluminum / garnet is 2.0 × 10 ⁻³ [a. u. The light emitting device according to claim 1, wherein the light emitting device is equal to or lower than / ° C.]. The first light source is covered by the first phosphor layer;
The light emitting device according to claim 1 or 2, wherein the first phosphor layer is covered with the second phosphor layer.

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