JP4895574B2 - Wavelength conversion member and light emitting device - Google Patents

Description

  The present invention relates to a wavelength conversion member containing phosphor particles and a light emitting device in which the phosphor is combined with a semiconductor light emitting element such as an LED or a semiconductor laser.

  A light-emitting device that converts light emitted from a semiconductor light-emitting element such as a light-emitting diode (LED) with a phosphor is small in size and consumes less power than an incandescent bulb. Development of high efficiency or high reliability is being carried out.

  Patent Document 1 discloses a light-emitting device that emits white light using a semiconductor light-emitting element that emits light with a wavelength of 390 nm to 420 nm and a phosphor that is excited by light emitted from the semiconductor light-emitting element. Various phosphors of oxides and sulfides are used as phosphors that emit light by excitation light having a wavelength of 390 to 420 nm.

  However, depending on the phosphor, for example, a phosphor containing sulfide may react with moisture in the air and hydrolyze. Due to such deterioration of the phosphor, the service life of the light emitting device is reduced. As a countermeasure, Patent Document 2 discloses a phosphor having a coating.

  In recent years, examples of oxynitrides and nitride phosphors are disclosed in Patent Document 3 and Patent Document 4 in place of oxides and sulfide-based phosphors. These phosphors are excited by light with a wavelength of 390 nm to 420 nm to obtain high-efficiency light emission, have high stability and water resistance, and have excellent characteristics such as little change in light emission efficiency due to changes in use temperature. Many have.

Patent Document 5 discloses that a coating of a metal nitride-based or metal oxynitride-based material is provided to further increase the heat resistance of the nitride phosphor. According to this, (Sr _a , Ca _1-a ) _x Si _y O _z N _{{(2/3) x + (4/3) y− (2/3) z}} : Eu, Since it is easy to be baked when producing x = 2 and y = 5, this phosphor is covered with a coating containing N element. As the film containing N element, a metal nitride-based material containing nitrogen and metals such as aluminum, silicon, titanium, boron and zirconium, and an organic resin containing N element such as polyurethane and polyurea are used. The nitride-based phosphor in which the film containing N element is not formed has its luminous efficiency drastically lowered by heating to 200 to 300 ° C., whereas nitriding is achieved by providing a film containing N element. It is said that the heat resistance is improved by reducing nitrogen decomposition of the physical fluorescent material by supplying nitrogen.

Further, as a prior art corresponding to an embodiment of the present invention in Patent Document 6, the phosphors are arranged in the order of a light emitting element, a red phosphor, a green phosphor, and a blue phosphor. A light emitting device in which reabsorption of light emitted from a body is suppressed is disclosed.
JP 2002-171000 A JP 2002-223008 A JP 2002-363554 A JP 2003-206481 A JP 2004-161807 A JP 2004-71357 A

  As described above, the reason for providing a coating film on the phosphor in the past has been to improve the chemical stability and heat resistance of the phosphor. However, it is considered that the coating also affects the incident efficiency of the excitation light to the phosphor particles and the extraction efficiency of the fluorescence from the phosphor particles. Here, when a nitride film is provided as in Patent Document 5, considering the combination with an oxynitride or a nitride phosphor, both are the same type of material based on nitride or nitride. Furthermore, the refractive index is similar, and when the difference from the refractive index of a medium made of resin or glass for holding the phosphor in a dispersed state becomes large, the incident efficiency of the excitation light on the phosphor particles and the fluorescence It is not sufficient in terms of the efficiency of extracting fluorescence from body particles.

  The present invention improves the wavelength conversion efficiency of the wavelength conversion member by providing a suitable film on the oxynitride or nitride phosphor particles in consideration of the medium such as resin or glass covering the periphery of the phosphor. With the goal. It is another object of the present invention to provide a light emitting device with favorable light emission efficiency.

  Hereinafter, means for solving the problems according to the present invention will be described. In addition, in order to explain the reason for using the means, some actions associated with the means are also described. Note that the present invention may have a plurality of actions or effects incidentally, but these effects are not intended to solve the problem but are incidental, and thus do not limit the invention. Absent.

The present invention relates to a phosphor particle made of oxynitride or nitride and having a refractive index n ₁ , a film covering the particle and having a refractive index n ₂ , and a refraction in which the phosphor particles having the film are dispersed. consists medium having a rate _{n 3,} the refractive index _{n 2} of said coating, the square root of _{n 1} × _{n 3} as _{n 13,} n 13 -0.2 or _more, and wherein the n 13 +0.2 or less It is the wavelength conversion member to do.

  In the present invention, the oxynitride phosphor particles are preferably phosphor particles containing Si, Al, O, N and one or more lanthanoid rare earth elements as composition elements. The material system composed of Si, Al, O, and N is a lanthanoid rare earth (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) that becomes the emission center. It becomes a wavelength conversion member excellent in wavelength conversion efficiency by mixing one sort or two sorts or more among them.

  In the present invention, the nitride phosphor particles are preferably phosphor particles containing Ca, Si, Al, N and one or more lanthanoid rare earth elements as composition elements. The material system composed of Ca, Si, Al, and N is a lanthanoid rare earth (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) that becomes the emission center. It becomes a wavelength conversion member excellent in wavelength conversion efficiency by mixing one sort or two sorts or more among them.

  In the present invention, the coating is preferably a metal oxide. Since metal oxides are generally transparent and stable, they are suitable as a coating of oxynitride phosphor particles or nitride phosphor particles.

  In the present invention, the coating is preferably magnesium oxide. Since the refractive index of magnesium oxide is, for example, about 1.74, the reflectance may be reduced by coating the particles of the oxynitride phosphor or the nitride phosphor.

  In the present invention, the coating film is preferably yttrium oxide. Since the refractive index of yttrium oxide is, for example, about 1.87, the reflectance may be reduced by coating the particles of the oxynitride phosphor or the nitride phosphor.

  In the present invention, the coating is preferably aluminum oxide. Since the refractive index of aluminum oxide is, for example, about 1.63, the reflectance may be reduced by coating the particles of the oxynitride phosphor or the nitride phosphor.

In the present invention, it is desirable that the film thickness is 5 nm or more and 3 μm or less.
In the present invention, the coating film may be formed by a sol-gel method.

  In the present invention, the coating film may be provided by attaching particles made of the coating material to the phosphor particles.

  In the present invention, the medium may be a silicone resin. Since the silicone resin has a siloxane bond (Si—O) as a skeleton, it is not easily deteriorated by blue to near ultraviolet light used as excitation light of the phosphor, and is suitable as a medium for a wavelength conversion member.

  In the present invention, the medium may be glass. Glass is suitable as a medium for a wavelength conversion member because it is hardly deteriorated by light from blue to near ultraviolet used as excitation light of a phosphor.

  The present invention includes particles of a first phosphor covered with the coating and having a fluorescence peak wavelength of 400 nm to 500 nm and a second phosphor covered with the coating and having a fluorescence peak wavelength of 500 nm to 600 nm. And a third phosphor particle covered with the coating and having a fluorescence peak wavelength of 600 nm to 700 nm may be dispersed in the medium. The coating of the first phosphor particles, the coating of the second phosphor particles, and the coating of the third phosphor particles may be made of different materials or the same kind of materials. There may be.

  The present invention includes a first wavelength conversion member covered with the coating and having fluorescent particles having a fluorescent peak wavelength of 400 nm to 500 nm and a fluorescent peak wavelength of 500 nm to 600 nm. A second wavelength conversion member having phosphor particles; and a third wavelength conversion member covered with the coating and having phosphor peak wavelengths of 600 nm to 700 nm dispersed in the medium. The wavelength conversion member characterized by the above may be used. The phosphor particle coating on the first wavelength conversion member, the phosphor particle coating on the second wavelength conversion member, and the phosphor particle coating on the third wavelength conversion member are made of different materials. It may be made of the same kind of material.

  The present invention is a light emitting device characterized in that the semiconductor light emitting element and the wavelength conversion member described above are arranged so that light emitted from the semiconductor light emitting element is incident thereon. Thereby, the light-emitting device excellent in wavelength conversion efficiency is obtained.

  The present invention includes a semiconductor light emitting element, and the light emitted from the semiconductor light emitting element is incident on the third wavelength conversion member, the second wavelength conversion member, and the first wavelength conversion member in this order. The light emitting device is characterized in that a wavelength conversion member is disposed.

  The present invention includes a semiconductor light emitting element, and the light emitted from the semiconductor light emitting element is incident on the second wavelength conversion member, the third wavelength conversion member, and the first wavelength conversion member in this order. The light emitting device is characterized in that a wavelength conversion member is disposed.

  In the present invention, the emission peak wavelength of the semiconductor light emitting device may be 370 nm or more and 480 nm or less.

  In the present invention, the emission peak wavelength of the semiconductor light emitting device may be 390 nm or more and 420 nm or less.

  In the present invention, the semiconductor light emitting element may be a semiconductor light emitting element made of a GaN-based semiconductor.

  The present invention relates to a wavelength conversion member in which oxynitride or nitride phosphor particles are dispersed in a medium such as a resin or glass, and the refraction near a square root of the product of the refractive index of the phosphor particles and the refractive index of the medium. By using a metal oxide material having a refractive index such as magnesium oxide, yttrium oxide or aluminum oxide to form a coating on the phosphor particles, the incident efficiency of excitation light on the phosphor particles and the fluorescence from the phosphor particles As a result, the wavelength conversion efficiency is improved.

  Moreover, this invention can improve luminous efficiency by setting it as the light-emitting device which combined said wavelength conversion member and the semiconductor light-emitting element.

The present invention relates to a phosphor particle made of oxynitride or nitride and having a refractive index n ₁ , a film covering the particle and having a refractive index n ₂ , and a refraction in which the phosphor particles having the film are dispersed. consists medium having a rate _{n 3,} the refractive index _{n 2} of said coating, the square root of _{n 1} × _{n 3} as _{n 13,} n 13 -0.2 or _more, and wherein the n 13 +0.2 or less It is the wavelength conversion member to do. As a specific example for the values of the refractive index, the phosphor refractive index n ₁ of 2.0 of the particles of oxynitride or nitride, when a refractive index n ₃ is 1.4 for the assumed medium a silicone resin _, the _{order n 13} is about 1.67, it is desirable refractive index _{n 2} of the film is 1.47 or more 1.87 or less.

In order to explain the relationship between the range of the refractive index n ₂ and the reflectance of a suitable coating, first, the reflectance when there is no coating will be described. A phosphor without a coating (refractive index = 2.0) is in the medium (refracted In the case of dispersion at a rate = 1.4), the reflectance at the phosphor interface is 3.11% ((2.0−1.4) ² /(2.0+1.4) ² ).

Next, the range of the refractive index n ₂ of the preferred coating will be described with reference to FIG. FIG. 1 is a graph in which the horizontal axis represents the refractive index n ₂ of the coating, and the vertical axis represents the reflectance R (calculated value) of the phosphor particles having the coating. However, considering that the film thickness and the incident angle of light on the film are random, the reflectance R obtained by averaging the light interference is used as the reflectance. Even in a phosphor with a film, when the refractive index n _{2 of the} film is 1.4, which is the same as the refractive index n _{3 of the} medium, and 2.0, which is the same as the refractive index n _{1 of the} phosphor, Same reflectivity. When the refractive index of the film is the square root (refractive index 1.67) of the product of the medium (refractive index 1.4) and the phosphor (refractive index 2.0), the reflectance is minimized (1.58%). Become. When this refractive index n _13, in which case, along with the reflectivity when the incident excitation light is incident efficiency of excitation light can be improved by reducing the fluorescence emission efficiency of the reduction in reflectance at the emission of fluorescence Will improve. As a result, the wavelength conversion efficiency increases by about 3.1%.

As the range of the refractive index _{n 2} of the film to obtain such an effect, the refractive index _{n 2} is 1.47 of the film (= 1.67-0.2) or 1.87 (= 1.67 + 0. 2) In the case of the following, the reflectance R is about 2.2% or less, which is about 0.9% lower than that in the case of 3.1% without the coating. Therefore, the incident efficiency of the excitation light and the emission of the fluorescence It can be estimated that the wavelength conversion efficiency increases by 1.8% in combination with the efficiency.

Further, when the refractive index n _{2 of the} coating is 1.52 (= 1.67−0.15) or more and 1.82 (= 1.67 + 0.15) or less, the reflectance R is about 1.9% or less. Therefore, it is estimated that the wavelength conversion efficiency is increased by 2.4% by combining the incident efficiency of the excitation light and the emission efficiency of the fluorescence because it is decreased by 1.2% compared to the case of 3.1% without the coating. it can.

Further, when the refractive index n _{2 of the} coating is 1.57 (= 1.67−0.1) or more and 1.77 (= 1.67 + 0.1) or less, the reflectance R is about 1.74% or less. Therefore, it is estimated that the wavelength conversion efficiency increases by 2.7% by combining the incident efficiency of the excitation light and the emission efficiency of the fluorescence because it decreases by 1.36% compared to the case of 3.1% without the coating. it can.

  Thus, by setting the refractive index of the coating within a suitable range, the reflectance of the phosphor particles is reduced, and the incident efficiency of excitation light and the emission efficiency of fluorescence are improved, so that the wavelength conversion efficiency is improved.

The film thickness is such that the interference effect is maximum (λ / n ₂ ) × (1/4 + M / 2), where λ is the wavelength of light and M is an integer. . For example, when the refractive index n _{2 of the} film is n ₁₃ above, the wavelength λ is 405 nm which is the wavelength of the excitation light in the embodiment, and M is zero, the film thickness of the film that maximizes the interference effect is 61 nm. It becomes. Since the effect of interference has a cosine relationship with the film thickness, if the value is about 1/4 (for example, 15 nm) or more of this value, the effect of reducing the reflectivity due to interference occurs. If it is / 3 or less (for example, 30 nm or more and 90 nm or less), it is considered that the reflectance reduction effect is sufficiently produced. The same can be said basically when M is an integer equal to or greater than 1, but when the film thickness is large, the dispersion of the film thickness distribution and the dispersion of the incident angle of light are averaged. Since the amplitude of the cosine-shaped reflectivity in the graph of thickness vs. reflectivity is attenuated, it is considered that a substantially constant interference effect occurs at a layer thickness of a certain level or more. In addition, the above-mentioned argument holds similarly by making wavelength (lambda) into the value of fluorescence with respect to fluorescence.

  In addition to the increase in wavelength conversion efficiency, the following effects can be obtained. By forming a film, non-emission process on the phosphor surface (excited electrons do not become non-excited by a transition accompanied by light emission, but become non-excited by a non-emission transition through a surface level). It is possible to reduce the surface level that is a factor of the above. Further, due to the surface modification effect, phosphor particles can be prevented from agglomerating and can be favorably dispersed in a medium made of resin or glass. Moreover, since the coating serves as a protective film for the phosphor particles by forming the coating, it is excellent in luminous efficiency and long-term stability of chromaticity. Experimentally, as shown in the embodiment, an increase in wavelength conversion efficiency is recognized when the film thickness is 5 nm or more and 3 μm or less, and it can be interpreted that there is an effect other than the interference effect.

  Therefore, the light emitting device using the phosphor on which the coating film of the present invention is formed can obtain good light emission efficiency and is excellent in light emission efficiency and long-term stability of chromaticity.

In the following, embodiments of the present invention will be described more specifically.
(Embodiment 1)
A phosphor 21 having a coating film according to Embodiment 1 of the present invention and a wavelength conversion member 31 using the same will be described.

As shown in FIG. 2A, Ce-activated α sialon (composition formula Ca _0.25 Ce _0.25 (Si, Al) ₁₂ (O, N) having an indefinite shape (sometimes close to a spherical shape). ₁₆ ) The coating film 10 is formed by adhering the child particles of magnesium oxide (refractive index 1.74) to the blue phosphor particles 11 having a refractive index of 2.0. The thickness of the phosphor coating 10 was an average of 80 nm (about 40 to 200 nm depending on the location) when the weight ratio of the magnesium oxide powder 46 was 0.1. As shown in FIG. 2B, the coating 10 may adhere while maintaining the shape of the child particles to some extent.

  Next, the wavelength conversion member 31 shown in FIG. 3 is produced as follows. The phosphor 21 having a coating is added to the liquid silicone resin raw material and mixed uniformly, and then a 0.5 mm thick sheet is cured by heating at 120 ° C. for 60 minutes to be converted into the wavelength conversion member 31. Is made. Since the refractive index of the silicone resin 24 that is the medium of the wavelength conversion member 31 is 1.4, the refractive index of the phosphor 11 is about 2.0, and the refractive index of the coating 10 is 1.74, the phosphor particles 11 It is possible to improve the incident efficiency of excitation light to the light and the extraction efficiency of fluorescence from the blue phosphor particles 11. In addition, by using the silicone resin 24 having a refractive index of about 1.3 to 1.6 as a medium of the wavelength conversion member 31, the incident efficiency of excitation light to the phosphor 21 having a coating and the phosphor 21 having the coating The wavelength conversion efficiency is improved because the fluorescence extraction efficiency is improved. As the medium, glass instead of resin may be used.

  As a comparative example, a wavelength conversion member (not shown) in which blue phosphor particles (not shown) on which a film made of silicon nitride (refractive index = 2.0) is formed is manufactured by the above method and dispersed in a silicone resin. ) Was produced. When the wavelength conversion efficiency was measured by irradiating the wavelength conversion member 31 according to the embodiment with excitation light having a wavelength of 405 nm, the wavelength conversion efficiency was higher than that of the wavelength conversion member of the comparative example by forming the magnesium oxide film 10. Improved by 5.2%. The reason why it is larger than the 3% improvement obtained in the estimation of the reflectance is that the surface level that causes the non-light-emitting process on the phosphor surface can be reduced by forming a film. Conceivable.

  In order to further examine the film thickness dependence, the ratio of the magnesium oxide powder 56 to the blue phosphor particles 11 is 0.006 (average film thickness 5 nm), 0.1 (average film thickness 80 nm, the above example), 1.0 ( Samples having an average film thickness of 650 nm and 10 (average film thickness of 3 μm) were prepared, and the wavelength conversion efficiency was compared by irradiating excitation light having a wavelength of 405 nm. The wavelength conversion efficiency is increased by 1.1%, 5.2%, 3.1%, and 1.3%, respectively, compared to the comparative example, and the improvement effect of the wavelength conversion efficiency within this film thickness range can be confirmed. It was.

  Moreover, since the surface modification effect is also produced by providing the coating, the phosphor particles can be favorably dispersed in a medium made of resin or glass without aggregating. In particular, since magnesium oxide has a strong tendency to be positively charged, it has an advantage that it is repelled by static electricity and hardly aggregates.

(Embodiment 2)
In Embodiment 2, a film of yttrium oxide was formed on the green phosphor particles 12 made of Eu-activated β sialon (Si, Al, O, N, and Eu as component elements) by a sol-gel method.

  A predetermined amount of ethanol 51, water 52, and yttrium alkoxide 53 (tributoxy yttrium) was added to the liquid container 50 shown in FIG. 4, and then hydrochloric acid 54 as a catalyst was added while stirring. Phosphor particles 12 (refractive index 2.0) are put into the mixture, and the mixture is stirred and heated to about 30 to 50 ° C. After 1 to 5 hours, the precipitate 56 in the liquid container 50 is taken out, heated to 100 ° C. to evaporate the solvent, and then baked in dry air at about 500 ° C. for several tens of minutes. In this manner, the phosphor 26 having the yttrium oxide film (refractive index 1.87) is produced. When the film thickness of the obtained phosphor film was measured, it was about 50 to 300 nm.

  Further, FIG. 5 shows a wavelength conversion member 36 using the phosphor 26 having this film and using glass 29 (refractive index 1.5) as a medium. The wavelength conversion member 36 was produced as follows. Water and ammonia for hydrolysis are added to an ethanol solution of tetraethoxysilane, which is a metal alkoxide, to form a glass sol. The phosphor 26 having a coating was added thereto, dipped on the glass substrate 39, and baked in dry air at 150 ° C. for 2 hours to produce the wavelength conversion member 36.

  Further, as a comparative example, a wavelength conversion member for comparison in which green phosphor particles 12 that do not form a film were dispersed in a resin by the above-described manufacturing method was prepared. Compared with the comparative wavelength conversion member, the wavelength conversion efficiency improved by 3.6%.

(Embodiment 3)
In Embodiment 3, an aluminum oxide film was formed on the red phosphor particles 13 made of CaAlSiN ₃ activated with Eu by a wet method.

  Pure water 52 and aluminum oxide fine powder 55 were placed in a liquid container 50 shown in FIG. 6 and stirred with a stirrer. Phosphor particles 13 (refractive index 2.0) were put in the mixture and stirred, and the resulting precipitate 57 was filtered. The filtered material was heated to about 110 ° C. to evaporate the water. As a result, a phosphor 27 having a coating film in which a coating film of aluminum oxide (refractive index of 1.63) was adhered to the phosphor particles was obtained.

  Further, FIG. 7 shows a wavelength conversion member 36 using the phosphor 27 having this film and using glass 29 (refractive index 1.5) as a medium. The wavelength conversion member 36 was produced as follows. Water and ammonia for hydrolysis were added to an ethanol solution of tetraethoxysilane, which is a metal alkoxide, to obtain a glass sol. A phosphor 27 having a coating was added thereto, dipped on a glass substrate 39, and baked in dry air at 150 ° C. for 2 hours to produce a wavelength conversion member 37.

(Embodiment 4)
Next, the light-emitting device 60 of Embodiment 4 is demonstrated using FIG.

The light emitting device 60 seals the base 65, the electrodes 66 and 67 formed on the surface thereof, the semiconductor light emitting element 64 electrically connected to the electrodes 66 and 67, the mirror 68, and the semiconductor light emitting element 64. A wavelength conversion member 69 that converts the light emitted from the semiconductor light emitting element 64 into fluorescence. The wavelength conversion member 69 includes a phosphor 21, 22, and 23 having a silicone resin 24 (refractive index of 1.4) serving as a medium and a film dispersed in the resin. Here, phosphors 21, 22, and 23 having coatings are blue phosphor particles 11 made of α-sialon activated with Ce, green phosphor particles 12 made of β-sialon activated with Eu, and CaAlSiN ₃ activated with Eu. For the red phosphor particles 13 made of magnesium oxide, a magnesium oxide film is formed by the method shown in the first embodiment.

  When a GaN-based semiconductor light-emitting element is used as the semiconductor light-emitting element 64, it is desirable that the light-emission peak wavelength is 390 nm to 420 nm with good electrical / optical conversion efficiency. An LED made of a semiconductor (a semiconductor containing at least Ga and N and using Al, In, an n-type dopant, a p-type dopant, or the like as needed) was used.

  The emission peak wavelengths of the phosphors 21, 22, and 23 having the coating are 490 nm, 540 nm, and 660 nm, respectively.

  The wavelength conversion member 69 was produced as follows. Phosphors 21, 22, and 23 having a coating were added to a liquid silicone resin raw material, mixed uniformly, poured onto the substrate 65, and cured by heating at 120 ° C. for 60 minutes. Since the refractive index of the silicone resin 24 which is the main component of the wavelength conversion member 69 is 1.4, the refractive index of the phosphor is about 2.0, and the refractive index of the coating made of magnesium oxide is 1.74, the fluorescence The incident efficiency of the excitation light to the body particles and the fluorescence extraction efficiency from the phosphor particles can be improved. By blending the three types of phosphor particles, a light emitting device 60 that shines in the color of chromaticity coordinates x = 0.32 and chromaticity coordinates y = 0.35, which is almost white, was obtained. Further, since the three primary colors can be emitted, and the half width of the emission spectrum of each phosphor is as wide as, for example, 50 nm or more, the color rendering properties are good.

  Thus, by using the wavelength conversion member in which the particles of the oxynitride phosphor having the coating or the particles of the nitride phosphor are dispersed, and the semiconductor light emitting device made of the GaN-based semiconductor, a small and substantially white color can be obtained. An efficient light-emitting device was obtained.

(Embodiment 5)
Next, the phosphor 21 having the coating produced in the first embodiment, the phosphor 26 having the coating produced in the second embodiment, and the phosphor 27 having the coating produced in the third embodiment were used. The light emitting device 70 will be described with reference to FIG.

  The light emitting device 70 includes a base 75, electrodes 76 and 77 formed on the surface thereof, a semiconductor light emitting element 74 electrically connected to the electrodes 76 and 77, a mirror 78, a red phosphor layer 73, and green fluorescent light. It consists of a body layer 72 and a blue phosphor layer 71. The phosphor layers 73, 72, 71 function as wavelength conversion members.

  As the semiconductor light emitting element 74, an LED made of a GaN-based semiconductor having an emission peak wavelength of 405 nm was used.

  A red phosphor layer 73, a green phosphor layer 72, and a blue phosphor layer 71 are laminated in this order from the side close to the semiconductor light emitting element 74, and the excitation light emitted from the semiconductor light emitting element 74 is converted into each color.

As the phosphor 21 having a coating dispersed in the blue phosphor layer 71, a coating of magnesium oxide coated on α activated sialon activated with Ce is used as a coating dispersed in the green phosphor layer 72. The phosphor 26 having Eu-activated β sialon provided with a magnesium oxide film is used as the phosphor 27 having the film dispersed in the red phosphor layer 73. Eu-activated CaAlSiN ₃ A film provided with a magnesium oxide coating is used. The respective emission peak wavelengths are 660 nm, 540 nm and 490 nm.

  The red phosphor layer 73 is produced as follows. After the phosphor 27 having a coating is uniformly mixed with the liquid silicone resin raw material, the liquid is injected into the base 75 and the resin is cured. Next, the green phosphor layer 72 is uniformly mixed with the phosphor 26 having a coating to the liquid silicone resin raw material, and then injected so as to overlap the red phosphor layer 73 to cure the resin. Further, the phosphor 21 having a coating is uniformly mixed with the blue phosphor layer 71, and then injected so as to overlap the green phosphor layer 72, and the resin is cured. As a result, a three-layer phosphor layer (wavelength conversion member) that also functions as a sealing material for the light emitting element is formed. By forming the phosphor layers in this order, the light emitted from the red phosphor layer 73 is not easily absorbed by the green phosphor layer 72 and the blue phosphor layer 71 thereon. Further, the light emitted from the green phosphor layer 72 is difficult to be absorbed by the blue phosphor layer 71. This is due to the fact that the phosphor generally has a smaller light absorptance in the longer wavelength region than the wavelength of the fluorescence compared to the light absorptance at the wavelength at which the phosphor emits fluorescence (see Patent Document 6). Therefore, light absorption by each phosphor layer can be reduced, and visible light can be efficiently emitted. In the case of the phosphor having the coating in the present embodiment, the reflection of light on the surface of the phosphor particles is small, and as a result, the reabsorption of fluorescence increases. The merit to reduce increases. As a result, the three primary colors can be emitted, and the half-value width of the emission spectrum of each phosphor is wide, for example, 50 nm or more in the case of an oxynitride phosphor and a nitride phosphor. Met.

(Embodiment 6)
Next, a light emitting device 80 having a wavelength conversion member arrangement different from that of the fifth embodiment will be described with reference to FIG.

  The light emitting device 80 includes a base body 75, electrodes 76 and 77 formed on the surface thereof, a semiconductor light emitting element 74 electrically connected to the electrodes, a mirror 78, a green phosphor layer 82, and a red phosphor. It consists of a layer 83 and a blue phosphor layer 81. The red phosphor layer 83 is the red phosphor layer 73 of the fifth embodiment, the green phosphor layer 82 is the green phosphor layer 72 of the fifth embodiment, and the blue phosphor layer 81 is the blue phosphor layer 71 of the fifth embodiment. The order of formation is different. Even with this arrangement, the green phosphor layer 82 and the red phosphor layer are arranged by disposing the blue phosphor layer 71 having low visibility and slightly lower luminous efficiency than the other colors at a position away from the semiconductor light emitting element 74. The re-absorption of blue fluorescence in 83 can be suppressed.

  Also according to the present embodiment, by using the blue phosphor layer 81 that absorbs a lot of excitation light as the uppermost layer, it is possible to efficiently extract green and red, and a white light emitting device having excellent wavelength conversion efficiency as a whole. can get. Thereby, the three primary colors can be emitted, and the half-value width of the emission spectrum of each phosphor is as wide as, for example, 50 nm or more, so that the color rendering is good.

(Other possible embodiments)
In the first embodiment, a wavelength conversion member using a medium made of resin is manufactured, and in the second and third embodiments, a wavelength conversion member using a medium made of glass is manufactured. However, this is an example, and the combination is reversed. May be.

  In Embodiments 4 to 6, a light emitting device using purple to near ultraviolet (wavelength of 420 nm or less) as a light source is shown, but a blue light source (light emission peak wavelength of 420 nm to 480 nm, for example, about 460 nm) is used. May be. In that case, blue and white can be obtained without using a blue phosphor. At present, the efficiency of the blue phosphor is slightly inferior to the efficiency of the other phosphors, so that the overall luminous efficiency can be increased by obtaining blue from the LED.

  As the semiconductor light emitting device, it is possible to use a semiconductor light emitting device made of an organic semiconductor, a zinc oxide semiconductor, or the like in addition to a semiconductor light emitting device made of a GaN-based semiconductor, and a semiconductor laser other than an LED may be used.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is explanatory drawing which shows the relationship between the refractive index of a film, and the reflectance of the fluorescent substance which has a film for demonstrating the fluorescent substance which has a film in the best form for implementing invention. FIG. 3 is a cross-sectional view of phosphor particles having a film in the first embodiment. 2 is a cross-sectional view of a wavelength conversion member in Embodiment 1. FIG. FIG. 10 is an explanatory diagram of a film forming process in the second embodiment. 6 is a cross-sectional view of a wavelength conversion member in Embodiment 2. FIG. 10 is an explanatory diagram of a film forming process in Embodiment 3. FIG. 6 is a sectional view of a wavelength conversion member in Embodiment 3. FIG. 7 is a cross-sectional view of a light-emitting device in Embodiment 4. FIG. 7 is a cross-sectional view of a light-emitting device in Embodiment 5. FIG. FIG. 10 is a cross-sectional view of a light-emitting device in Embodiment 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Coating 11 Blue phosphor particle, 12 Green phosphor particle, 13 Red phosphor particle 21, 22, 23, 26, 27 Phosphor having coating 24 Silicone resin, 29 Glass, 31, 36, 37, 69 Wavelength conversion member 39 Glass substrate, 50 Liquid container 51 Ethanol, 52 Water, 53 Yttrium alkoxide 54 Hydrochloric acid 55 Fine powder of aluminum oxide, 56, 57 Precipitate 60, 70, 80 Light emitting device, 65, 75 Substrate 66, 67, 76, 77 Electrode, 64, 74 Semiconductor light emitting device 68, 78 Mirror 71, 81 Blue phosphor layer, 72, 82 Green phosphor layer 73, 83 Red phosphor layer

Claims (16)

And phosphor particles having a refractive index n ₁ consisting of oxynitride or nitride, covering the particles, and a coating having a refractive index n ₂ of a metal oxide, are dispersed particles of a phosphor having a coating A medium having a refractive index n ₃ made of resin or glass ,
The refractive index n ₂ of the coating, the square root of n ₁ × n ₃ as n _13, n ₁₃ -0.2 or more, a Der Ru wavelength conversion member following n ₁₃ +0.2,
The phosphor particles having the coating are covered with the coating, and the first phosphor particles having a fluorescence peak wavelength of 400 nm or more and 500 nm or less are covered with the coating, and the fluorescence peak wavelength is 500 nm or more and 600 nm or less. A wavelength conversion member comprising: a second phosphor particle; and a third phosphor particle that is covered with the coating and has a fluorescence peak wavelength of 600 nm to 700 nm . And phosphor particles having a refractive index n ₁ consisting of oxynitride or nitride, covering the particles, and a coating having a refractive index n ₂ of a metal oxide, are dispersed particles of a phosphor having a coating A medium having a refractive index n ₃ made of resin or glass ,
The refractive index n ₂ of the coating, the square root of n ₁ × n ₃ as n _13, n ₁₃ -0.2 or more, a Der Ru wavelength conversion member following n ₁₃ +0.2,
A first wavelength conversion member covered with the coating and having fluorescent peak wavelengths of 400 nm or more and 500 nm or less dispersed in the medium, and a fluorescent peak wavelength of 500 nm or more and 600 nm covered with the coating. The second wavelength conversion member in which the following phosphor particles are dispersed in the medium, and the phosphor particles having a peak fluorescence wavelength of 600 nm to 700 nm are dispersed in the medium. A wavelength conversion member comprising a third wavelength conversion member . Particles of the oxynitride phosphor, Si, Al, O, to claim 1 or 2, characterized in that the particles of the phosphor containing as N and one or two or more lanthanoid rare earth element composition element The wavelength conversion member as described. Any the nitride phosphor particles, Ca, Si, Al, claim 1, wherein the N and one or two or more lanthanoid rare earth element is a phosphor particle comprising a composition element 3 The wavelength conversion member as described in any one .   The wavelength conversion member according to claim 1, wherein the coating is magnesium oxide. It said coating, the wavelength converting member according to claim 1, any one of 4, which is a yttrium oxide. It said coating, the wavelength converting member according to claim 1, any one of 4, wherein the aluminum oxide.   The film thickness of the said film is 5 nm or more and 3 micrometers or less, The wavelength conversion member as described in any one of Claim 1 to 7 characterized by the above-mentioned.   The wavelength conversion member according to claim 1, wherein the coating film is formed by a sol-gel method.   The wavelength conversion member according to claim 1, wherein the medium is a silicone resin. A semiconductor light emitting device, the light emitting device, wherein the semiconductor light emitting element emits light with a wavelength conversion member according to any one of claims 1 to 10 which is adapted to be incident. Comprising a semiconductor light-emitting device, the semiconductor light emitting element emits light, the third wavelength converting member, the second wavelength conversion member, so as to enter the order of the first wavelength conversion member, according to claim 2 A light emitting device characterized in that a wavelength conversion member is arranged. Comprising a semiconductor light-emitting device, the semiconductor light emitting element light emitted, the second wavelength conversion member, the third wavelength converting member, so as to enter the order of the first wavelength conversion member, according to claim 2 A light emitting device characterized in that a wavelength conversion member is arranged. The light emitting device according to any one of claims 11 to 13, the emission peak wavelength of the semiconductor light emitting element is characterized in that at 480nm or less than 370 nm. The light emitting device according to any one of claims 11 to 13 , wherein an emission peak wavelength of the semiconductor light emitting element is 390 nm or more and 420 nm or less. The semiconductor light emitting element, the light emitting device according to any one of claims 11 to 15 which is a semiconductor light emitting element made of a GaN-based semiconductor.

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