Wavelength conversion member and light emitting device

Abstract

A wavelength conversion member according to the present invention is provided with a phosphor plate including an inorganic base material and a phosphor dispersed in the inorganic base material, and a reflective multilayer film formed on the surface of one surface side of the phosphor plate and formed by laminating a plurality of inorganic films having different refractive indexes, the wavelength conversion member is configured such that, when measured in accordance with JIS Z 8781-4, in L * a * b * chromaticity coordinates of the surface of the reflective multilayer film formed on the one surface of the phosphor plate, the a * value satisfies-20 to 0 and / or the b * value satisfies 20 to 60.

Description

Technical Field

[0001] The invention relates to a wavelength conversion component and a light-emitting device. Background Art

[0002] Various developments have been made on light-emitting devices. As such a technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes a light-emitting device comprising: a semiconductor light-emitting element; a plate-shaped light wavelength conversion component (fluorescent ceramic) which is arranged opposite to the light-emitting surface of the semiconductor light-emitting element and converts the wavelength of light emitted by the semiconductor light-emitting element; and a filter layer formed on at least one of the surfaces of the plate-shaped light wavelength conversion component opposite to the semiconductor light-emitting element and the side surfaces, transmitting the light emitted from the semiconductor light-emitting element and reflecting the light whose wavelength is converted in the light wavelength conversion component (claim 1, paragraph 0037, etc. of Patent Document 1).

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-021582 Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] However, as a result of research conducted by the inventors of the present invention, it was found that the light wavelength conversion component having a filter layer on the irradiation surface side of the excitation light described in the above-mentioned Patent Document 1 still has room for improvement in terms of luminous intensity.

[0008] Means for solving technical problems

[0009] As a result of further research, the inventors of this case found that the luminous intensity of the phosphor plate can be improved by forming a reflective multilayer film on the excitation light irradiation side of the phosphor plate including an inorganic matrix and phosphors dispersed in the inorganic matrix and appropriately controlling the color tone of the surface of the laminated reflective multilayer film. Based on this understanding, further in-depth research found that by using L * a * b * Chromaticity coordinates are used as hue indicators, and a * Value and / or b * The reflective multilayer film having a value within a predetermined range can improve the emission intensity of the phosphor plate when the excitation light is irradiated through the reflective multilayer film, thereby completing the present invention.

[0010] According to one aspect of the present invention, the following wavelength conversion member and a light emitting device using the same can be provided.

[0011] 1. A wavelength conversion component, comprising:

[0012] A phosphor plate comprises an inorganic matrix and a phosphor dispersed in the inorganic matrix, and

[0013] A reflective multilayer film is formed on a surface of one side of the phosphor plate and is formed by laminating a plurality of inorganic films having different refractive indices;

[0014] The wavelength conversion component is composed of:

[0015] When measured according to JIS Z 8781-4, the L * a * b * In the chromaticity coordinates,

[0016] a * The value satisfies -20 or more and 0 or less, and / or

[0017] b * The value satisfies 20 or more and 60 or less.

[0018] 2. The wavelength conversion component according to 1, wherein:

[0019] In the diffuse reflection spectrum of one surface of the phosphor plate on which the reflective multilayer film is formed, the diffuse reflectance at 450 nm is 35% or less.

[0020] 3. The wavelength conversion component according to 1 or 2, wherein:

[0021] In the diffuse reflection spectrum of one surface side of the phosphor plate on which the reflective multilayer film is formed, the diffuse reflectance at 600 nm is 82% or more.

[0022] 4. The wavelength conversion component according to any one of 1 to 3, wherein:

[0023] When blue excitation light is irradiated from one side where the reflective multilayer film is formed, the peak wavelength of the emission spectrum detected from the other side of the phosphor plate located opposite to the reflective multilayer film is within the range of 580 nm to 620 nm.

[0024] 5. The wavelength conversion component according to any one of 1 to 4, wherein:

[0025] On the surface of one side of the phosphor plate, Rsm measured in accordance with JIS B 0031:1994 is 60 μm or less.

[0026] 6. The wavelength conversion component according to any one of 1 to 5, wherein:

[0027] The reflective multilayer film has a periodic stacked structure in which at least one of a high-refractive-index inorganic film and a low-refractive-index inorganic film is stacked with substantially the same thickness.

[0028] 7. The wavelength conversion component according to 6, wherein:

[0029] The reflective multilayer film includes an asymmetric stacked structure disposed adjacent to the periodic stacked structure and in which at least one of the high refractive index inorganic film and the low refractive index inorganic film is stacked with different thicknesses.

[0030] 8. The wavelength conversion component according to any one of 1 to 7, wherein:

[0031] The phosphor includes any one of an α-sialon phosphor, a (Ba, Sr, Ca) 2 Si 5 N 8 phosphor, a mixture of a YAG phosphor and a SCASN phosphor, and a SCASN phosphor.

[0032] 9. The wavelength conversion component according to any one of 1 to 7, wherein:

[0033] The inorganic base material contains alumina or a spinel compound.

[0034] 10. A light emitting device comprising the wavelength conversion component according to any one of 1 to 9 and a light source.

[0035] 11. The lighting device according to 10, which is a direction indicator.

[0036] Effects of the Invention

[0037] According to the present invention, a wavelength conversion member having excellent light emission intensity and a light emitting device using the wavelength conversion member can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a cross-sectional view schematically showing a structural example of a wavelength conversion member according to the present embodiment.

[0039] Figure 2 It is a cross-sectional view schematically showing a structural example of a light emitting device according to this embodiment.

[0040] Figure 3 These are the SEM images of Example 2 and the SEM images of Comparative Example 3. DETAILED DESCRIPTION

[0041] Hereinafter, the embodiments of the present invention will be described using the accompanying drawings. In addition, in all the drawings, the same components are marked with the same symbols, and the description is appropriately omitted. In addition, the drawings are schematic diagrams and are not consistent with the actual size ratios.

[0042] The outline of the wavelength conversion member according to the present embodiment will be described.

[0043] The wavelength conversion member of this embodiment includes: a phosphor plate including an inorganic matrix and phosphors dispersed in the inorganic matrix; and a reflective multilayer film formed on a surface of one side of the phosphor plate and formed by stacking a plurality of inorganic films having different refractive indices.

[0044] The reflective multilayer film functions as a dichroic filter layer, utilizing light interference to transmit light in a specific wavelength region (blue excitation light emitted from a light source) and reflect light in other wavelength regions (light emitted from a phosphor after wavelength conversion of the blue excitation light). This allows light emitted from the phosphor to be efficiently extracted from the other side of the phosphor plate.

[0045] The wavelength conversion member of this embodiment uses L * a * b * The chromaticity coordinates are used as an index of the color tone of the surface of the reflective multilayer film formed on one side of the phosphor plate, where a * Value and / or b * The value needs to be within the specified range.

[0046] L * a * b * The chromaticity coordinates can be measured in accordance with JIS Z 8781-4.

[0047] About L * a * b * The objects for measuring the chromaticity coordinates are, first, the surface of the reflective multilayer film formed on one side of the phosphor plate (i.e., the reflective multilayer film surface on one side of the phosphor plate), and second, the surface on the other side of the phosphor plate located on the opposite side to the reflective multilayer film (the exposed surface of the phosphor plate when no functional film such as a reflective film is formed).

[0048] The wavelength conversion member of this embodiment is configured to reflect the L of the multilayer film surface. * a * b * The chromaticity coordinates satisfy the following first condition, or are configured such that the L of the reflective multilayer film surface relative to the exposed surface * a * b * The chromaticity coordinate difference satisfies the following second condition. Thereby, the light emission intensity of the wavelength conversion member can be further improved.

[0049] Although the detailed mechanism is not yet clear, it is believed that since the stacked structure of the reflective multilayer film can be maintained in an appropriate state and formed on one surface of the phosphor plate in this state, the reduction in the dichroic filtering function of the reflective multilayer film can be fully suppressed, thereby improving the luminous intensity.

[0050] About L * a * b * The first condition of chromaticity coordinates, a * The value satisfies -20 or more and 0 or less, and / or b * The value satisfies 20 or more and 60 or less.

[0051] In the first condition above, a * The value is -20 or more and 0 or less, preferably -15 or more and 0 or less, and more preferably -10 or more and -1 or less. * The value is 20 or more and 60 or less, preferably 23 or more and 58 or less, and more preferably 25 or more and 55 or less. * The value is, for example, 80 or more and 100 or less, preferably 85 or more and 100 or less, and more preferably 90 or more and 99 or less.

[0052] The L of the reflective multilayer film surface * a * b * The values ​​are set to L1 * value, a1 * value, b2 * The L value of the surface on the other side of the phosphor plate opposite to the reflective multilayer film (the exposed surface of the phosphor plate when no other functional layer is formed) is calculated. * a * b * The values ​​are set to L2 * value, a2 * value, b2 * value.

[0053] About L * a * b * The second condition of chromaticity coordinates, (a1 * Value - a2 * value) satisfies -30 or more and -7 or less, and / or (b1 * Value-b2 * value) satisfies 0 or more and 50 or less.

[0054] In the above second condition, (a1 * Value - a2 *On the other hand, (b1 * Value-b2 * value) is 0 or more and 50 or less, preferably 5 or more and 45 or less, and more preferably 10 or more and 40 or less. * Value-L2 * The value) is, for example, 0 to 20, preferably 0 to 15, and more preferably 1 to 10.

[0055] In this embodiment, for example, the L of the reflective multilayer film can be controlled by appropriately selecting the type and amount of each component contained in the reflective multilayer film, the method for manufacturing the reflective multilayer film, etc. * a * b * Value. Among them, as L for making the above-mentioned reflective multilayer film * a * b * Factors for making the value fall within the desired numerical range include, for example, grinding / polishing one side of the phosphor plate (the surface on which the reflective multilayer film is formed) using a grindstone or abrasive grains of a specified particle size, and appropriately selecting the stacking structure of the reflective multilayer film.

[0056] The wavelength conversion component of this embodiment can be used in light-emitting devices for various purposes, for example, it can be used in vehicle lamps and lighting lamps other than vehicle lamps. Among vehicle lamps, it is preferably used for direction indicators (sometimes also called flashers (winkers), turn lamps (turn lamps), or warning lights (hazard lamps)). In addition, vehicles include automobiles, two-wheeled vehicles, railway vehicles, etc.

[0057] The structure of the wavelength conversion member of this embodiment will be described in detail.

[0058] Figure 1 It is a cross-sectional view schematically showing a structural example of the wavelength conversion member 10 .

[0059] The wavelength conversion member 10 includes a phosphor plate 20 and a reflective multilayer film 30 formed on one surface 21 of the phosphor plate 20. An excitation light source is disposed on the surface of the wavelength conversion member 10 on which the reflective multilayer film 30 is formed, and excitation light is irradiated.

[0060] (Phosphor Plate)

[0061] The phosphor plate 20 is composed of a plate-shaped composite body in which phosphors are dispersed in an inorganic matrix.

[0062] In the composite body constituting the phosphor plate, the phosphor and the matrix composed of an inorganic substance are mixed. Specifically, the phosphor may be dispersed in the sintered product of the compound constituting the inorganic matrix. The phosphor may be uniformly dispersed in the inorganic matrix in the form of particles.

[0063] The inorganic matrix material may be a main component of the composite. In this case, the content of the matrix material in the composite may be, for example, 50 vol% or more, preferably 60 vol% or more, in terms of volume.

[0064] The inorganic matrix may be composed of a sintered product of a metal oxide, wherein the sintered product of the metal oxide includes a sintered product of Al2O3, a sintered product of SiO2, and a spinel compound M 2x Al 4-4x O 6-4x At least one of the sintered products (wherein M is at least any one of Mg, Mn, and Zn, and 0.2<x<0.6). These can be used alone or in combination of two or more. From the viewpoint of thermal properties and transparency, the base material can be composed of alumina or a sintered product containing a spinel compound.

[0065] The sintered Al2O3 has less absorption of visible light, so it can improve the luminous intensity of the phosphor plate. In addition, the sintered Al2O3 has high thermal conductivity, so it can improve the heat resistance of the phosphor plate. In addition, the sintered Al2O3 has excellent mechanical strength, so it can improve the durability of the phosphor plate.

[0066] The sintered product of SiO2 can be composed of a glass matrix. As the glass matrix, silica glass or the like can be used.

[0067] The sintered product containing the spinel-based compound is generally obtained by mixing a powder of a metal oxide represented by the general formula MO (M is at least one of Mg, Mn, and Zn) and a powder of Al 2 O 3 , followed by sintering.

[0068] Spinel refers to a composition stoichiometrically represented by x=0.5 (ie, general formula MAl2O4).

[0069] Among them, depending on the ratio of the amount of MO to the amount of Al2O3 in the raw materials, it will become a spinel compound with a non-stoichiometric composition in which MO or Al2O3 is excessively dissolved.

[0070] The sintered body containing the spinel compound represented by the above general formula will be relatively transparent. Therefore, excessive scattering of light in the phosphor plate will be suppressed. In addition, from the viewpoint of transparency, it is preferred to use a spinel compound in which M in the above general formula is Mg.

[0071] The phosphor may be any of various known phosphors depending on the intended use, and may include, for example, at least one of an α-sialon phosphor, a (Ba, Sr, Ca) 2 Si 5 N 8 phosphor, a mixture of a YAG phosphor and a SCASN phosphor, and a SCASN phosphor.

[0072] For example, when blue excitation light with a wavelength of 450 nm is irradiated from one surface 21 on which the reflective multilayer film 30 is formed, the emission spectrum detected from the other surface 22 of the phosphor plate 20 located on the opposite side of the reflective multilayer film 30 is measured. By using the phosphor plate 20 containing the phosphor exemplified above, it is possible to configure the emission spectrum so that the peak wavelength is within the range of 580 nm or more and 620 nm.

[0073] Furthermore, from the perspective of controlling the above-mentioned peak wavelength within the range of 585nm to 605nm, an α-type Sialon phosphor can be used, from the perspective of controlling the peak wavelength within the range of 605nm to 620nm, a (Ba,Sr,Ca)2Si5N8 phosphor can be used, from the perspective of controlling the peak wavelength within the range of 580nm to 620nm, a mixture of a YAG phosphor and a SCASN phosphor can be used, and from the perspective of controlling the peak wavelength near 620nm, a SCASN phosphor can be used.

[0074] When a single body of YAG phosphor is used as the phosphor, the peak wavelength is approximately 540 to 570 nm.

[0075] As the α-sialon phosphor, an α-sialon phosphor containing the Eu element represented by the following general formula (1) can be used.

[0076] (M) m(1-x) / p (Eu) mx / 2 (Si) 12-(m+n) (Al) m+n (O) n (N) 16-n ……General formula (1)

[0077] In the above general formula (1), M represents one or more elements selected from the group consisting of Li, Mg, Ca, Y and lanthanide elements (excluding La and Ce), p represents the valence of the M element, 0<x<0.5, 1.5≤m≤4.0, 0≤n≤2.0. For example, n can be 2.0 or less, 1.0 or less, or 0.8 or less. Generally speaking, a phosphor in which M is Ca is called a Ca-α type sialon phosphor.

[0078] Regarding the solid solution composition of α-sialon, the unit cell of α-silicon nitride (Si 12 N 16) is replaced by Al-N bonds, and n Si-N bonds are replaced by Al-O bonds. In order to maintain electrical neutrality, m / p cations (M, Eu) penetrate and dissolve in the lattice, as shown in the above general formula. In particular, if Ca is used as M, α-sialon is stabilized in a wide range of compositions, and by replacing a part of it with Eu that becomes the luminescence center, a phosphor that is excited by light in a wide wavelength range from ultraviolet to blue and emits visible light from yellow to orange can be obtained.

[0079] The solid solution composition of α-Sialon cannot be strictly defined due to the second crystalline phase different from α-Sialon and the inevitable presence of an amorphous phase. α-Sialon may contain β-Sialon, aluminum nitride or its polytype, Ca2Si5N8, CaAlSiN3, etc. as other crystalline phases.

[0080] As a method for manufacturing an α-sialon phosphor, there is a method of heating a mixed powder composed of silicon nitride, aluminum nitride and a compound of an intrusive solid solution element in a high-temperature nitrogen environment to react it. During the heating process, a part of the constituent components will form a liquid phase, and the substance will move into the liquid phase, thereby generating an α-sialon solid solution. Regarding the synthesized α-sialon phosphor, a plurality of equiaxed primary particles are sintered to form blocky secondary particles. The primary particle in this embodiment refers to the smallest particle that has the same crystal orientation within the particle and can exist alone.

[0081] As the (Ba, Sr, Ca) 2 Si 5 N 8 phosphor, a phosphor containing the Eu element can be used.

[0082] As the SCASN phosphor, for example, a phosphor activated with the Eu element in a mother crystal of alkaline earth silicon nitride represented by (Sr, Ca)AlSiN 3 can be used.

[0083] The lower limit of the average particle size of the phosphor is, for example, preferably 1 μm or more, more preferably 2 μm or more. This can increase the luminous intensity. In addition, the upper limit of the average particle size of the phosphor is preferably 30 μm or less, more preferably 20 μm or less. The average particle size of the phosphor is the size of the secondary particles described above. By setting the average particle size to 5 μm or more, the transparency of the composite can be further improved. On the other hand, by setting the average particle size of the phosphor to 30 μm or less, it is possible to suppress fragmentation when the phosphor plate is cut using a cutting machine or the like.

[0084] Here, the average particle size of the phosphor refers to the particle size D50 at which the cumulative amount (cumulative pass rate) from the smaller particle size side reaches 50% in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measurement method (manufactured by Beckman Coulter, Inc., LS13-320).

[0085] The lower limit of the content of the phosphor in 100 vol% of the composite constituting the phosphor plate 20 is, for example, 5 vol% or more, preferably 10 vol% or more, and more preferably 15 vol% or more. This can increase the luminous intensity of the thin phosphor plate and improve the light conversion efficiency of the phosphor plate.

[0086] On the other hand, the upper limit of the content of the phosphor in 100 vol% of the composite is, for example, 60 vol% or less, preferably 50 vol% or less, and more preferably 40 vol% or less. This can suppress a decrease in thermal conductivity of the phosphor plate.

[0087] The thickness of the phosphor plate 20 can be appropriately set according to the application.

[0088] The lower limit of the thickness of the phosphor plate 20 is, for example, 50 μm or more, preferably 80 μm or more, and more preferably 100 μm or more.

[0089] The upper limit of the thickness of the phosphor plate 20 is, for example, 1 mm or less, preferably 500 μm or less, and more preferably 300 μm or less. By setting the thickness within such a range, light extraction efficiency can be improved, and emission intensity can be increased.

[0090] The plane shape when viewed from the perpendicular direction with respect to one side 21 of the phosphor plate 20 may be a circular shape or a quadrilateral shape. In addition, by setting the plane shape of the phosphor plate 20 during transportation to a circular shape, it is possible to suppress corner defects or cracks, and improve durability or transportation performance, compared with the case of a quadrilateral shape.

[0091] The surface of one surface 21 of the phosphor plate 20 may be configured such that the upper limit of Rsm measured in accordance with JIS B 0031: 1994 is, for example, 60 μm or less, preferably 55 μm or less, and more preferably 50 μm or less. On the other hand, the lower limit of Rsm is not particularly limited and may be 1 μm or more.

[0092] Here, Rsm refers to the average length from a convex portion to an adjacent concave portion on the surface.

[0093] The surface on the other surface 22 side of the phosphor plate 20 may be configured so that Rsm satisfies the above numerical range, but does not necessarily have to do so.

[0094] (Reflective multilayer film)

[0095] The reflective multilayer film 30 is composed of a dielectric multilayer film in which a plurality of inorganic films having different refractive indices are stacked, that is, the reflective multilayer film 30 is composed of a stacked film in which high-refractive-index inorganic films and low-refractive-index inorganic films are alternately stacked.

[0096] Examples of the material of the high refractive index inorganic film include titanium oxide, niobium oxide, lanthanum oxide, tantalum oxide, yttrium oxide, gadolinium oxide, tungsten oxide, hafnium oxide, aluminum oxide, and silicon nitride.

[0097] Examples of the material of the low-refractive-index inorganic film include silicon oxide and the like.

[0098] The number of layers of the inorganic film in the reflective multilayer film 30 is not particularly limited, and may be, for example, 2 to 100 layers, and preferably 10 to 60 layers.

[0099] The thickness of the reflective multilayer film 30 is not particularly limited, and may be, for example, 0.1 to 20 μm, preferably 0.5 to 5 μm.

[0100] The reflective multilayer film 30 may include a periodic stacked structure in which at least one or both of a high-refractive-index inorganic film and a low-refractive-index inorganic film are stacked with substantially the same thickness.

[0101] In the periodic stacked structure, the thicknesses of the high refractive index inorganic film and the low refractive index inorganic film do not need to be substantially the same, and may be different. Substantially the same means that the thicknesses are within a range of ±10%.

[0102] The periodic stacking structure may exist near the center of the reflective multilayer film 30 .

[0103] Furthermore, the total number of stacked layers of the high-refractive-index inorganic film and the low-refractive-index inorganic film in the periodic stacked structure may be, for example, 4 to 30 layers, or 6 to 20 layers.

[0104] The thickness of each inorganic layer can be measured from a map created by plotting the brightness using a STEM cross-sectional image of the reflective multilayer film 30 .

[0105] Furthermore, the reflective multilayer film 30 may include an asymmetric stacked structure disposed adjacent to one or both sides of the periodic stacked structure. In the asymmetric stacked structure, at least one or both of the high refractive index inorganic film and the low refractive index inorganic film are stacked with different thicknesses.

[0106] In the asymmetric stacked structure, the thicknesses of the high-refractive-index inorganic film and the low-refractive-index inorganic film do not need to be substantially the same, and may be different.

[0107] The reflective multilayer film 30 having a stacked structure of a periodic stacking structure or a periodic stacking structure and an asymmetric stacking structure as described above has a high transmittance to blue excitation light, and a high reflectivity to the luminescence of the phosphor with a peak wavelength above 580nm and in the range of 620nm, thereby being able to further improve the luminescence extraction efficiency of the wavelength conversion component 10.

[0108] In the diffuse reflection spectrum of one surface 21 of the phosphor plate 20 having the reflective multilayer film 30 formed thereon, the diffuse reflectance at 450 nm is, for example, 35% or less, preferably 30% or less, and more preferably 25% or less. This can increase the transmittance of blue excitation light.

[0109] In the diffuse reflection spectrum of one surface 21 of the phosphor plate 20 formed with the reflective multilayer film 30, the diffuse reflectance at 600 nm is, for example, 82% or more, preferably 85% or more, and more preferably 90% or more. Thus, the reflectance of the luminescence of the phosphor having a peak wavelength of 580 nm or more and 620 nm can be increased.

[0110] An example of a process for producing the wavelength conversion member 10 according to the present embodiment will be described.

[0111] The method for manufacturing the wavelength conversion member 10 of the present embodiment includes: a step of forming the phosphor plate 20 ; and a step of forming the reflective multilayer film 30 on one surface 21 of the phosphor plate 20 .

[0112] An example of the process of forming the phosphor plate 20 may include: a step (1) of obtaining a mixture containing a metal oxide and a phosphor; and a step (2) of firing the obtained mixture.

[0113] The present invention is not limited to the above steps (1) and (2). For example, the phosphor plate may be formed by melting a metal oxide and mixing phosphor particles with the obtained melt.

[0114] In step (1), the powder of the phosphor or metal oxide used as a raw material is preferably of as high purity as possible, and the impurity content of elements other than the constituent elements is preferably 0.1% or less, and more preferably 0.01% or less.

[0115] The raw material powders can be mixed by various methods, such as dry method and wet method. However, a method is preferred in which the phosphor particles used as the raw material are not crushed as much as possible and impurities from the device are not mixed as much as possible during mixing.

[0116] As the metal oxide of the phosphor raw material, a metal oxide containing at least one of Al2O3 powder, SiO2 powder and spinel raw material powder can be used. These can be used alone or in combination of two or more.

[0117] The metal oxide may be in the form of fine powder, and its average particle size may be, for example, 1 μm or less.

[0118] As the raw material metal oxide, alumina powder (Al2O3) can be used.

[0119] The upper limit of the BET specific surface area of ​​the alumina powder is, for example, 10.0 m 2 / g or less, preferably 9.0m 2 / g or less, more preferably 8.0m 2 / g or less, more preferably 6.0m 2 / g or less. This can suppress the blackening of the phosphor plate. On the other hand, the lower limit of the BET specific surface area of ​​the alumina powder is, for example, 0.1 m 2 / g or more, preferably 0.5m 2 / g or more, more preferably 1.0 m 2 / g or more, more preferably 2.0m 2 This can improve the sinterability of the alumina powder and form a dense composite.

[0120] In step (2), the mixture of alumina powder and phosphor powder can be sintered at a temperature of, for example, 1300° C. to 1650° C. The heating temperature in the sintering step is more preferably 1500° C. to 1600° C. In order to densify the composite, the sintering temperature is preferably higher, but if the sintering temperature is too high, the phosphor reacts with alumina and the luminous intensity of the phosphor plate decreases, so it is preferably within the above range.

[0121] When the firing temperature is in the high temperature range of about 1600° C. to 1650° C., the holding time of the temperature is, for example, 20 minutes or less, preferably 15 minutes or less. This can increase the light emission intensity of the phosphor plate.

[0122] As the raw material metal oxide, glass powder (powder containing SiO2) can be used.

[0123] As the glass powder, SiO2 powder (silicon dioxide powder) or general glass raw materials can be used. These can be used alone or in combination of two or more.

[0124] As the raw material metal oxide, spinel raw material powder can be used.

[0125] Here, the "spinel raw material powder" is, for example, (i) containing the above-mentioned general formula M 2x Al 4-4x O 6-4x A mixture of a powder of a spinel compound represented by and / or (ii) a powder of a metal oxide represented by the general formula MO (M is at least one of Mg, Mn, and Zn) and a powder of Al2O3.

[0126] In step (2), the spinel raw material powder may be sintered at a temperature of, for example, 1300° C. to 1650° C. The heating temperature in the sintering step is more preferably 1500° C. to 1600° C. In order to densify the composite, the sintering temperature is preferably higher, but if the sintering temperature is too high, the luminous intensity of the phosphor plate will decrease, so it is preferably within the above range.

[0127] When the firing temperature is in the high temperature range of about 1600° C. to 1650° C., the holding time of the temperature is, for example, 20 minutes or less, preferably 15 minutes or less. This can increase the light emission intensity of the phosphor plate.

[0128] In the above-mentioned production method, the firing method may be pressureless sintering or pressured sintering. In order to suppress the degradation of the characteristics of the phosphor and obtain a dense composite, pressured sintering is preferred because it is easier to densify than pressureless sintering.

[0129] Examples of the pressure sintering method include hot pressing, spark plasma sintering (SPS), hot isostatic pressing (HIP), etc. In the case of hot pressing or SPS, the pressure is 10 MPa or more, preferably 30 MPa or more, and 100 MPa or less, preferably 80 MPa or less.

[0130] In order to prevent oxidation of the phosphor, the firing environment is preferably a non-oxidizing inert gas such as nitrogen or argon, or a vacuum environment.

[0131] Through the above operations, the phosphor plate 20 can be obtained.

[0132] Surface treatment is applied to at least one surface 21 (the surface on which the reflective multilayer film 30 is formed) or to both one surface 21 and the other surface 22 of the obtained phosphor plate 20 .

[0133] Examples of the surface treatment include grinding using a diamond grindstone or the like, polishing such as grinding, buffing, and polishing.

[0134] The other surface 22 of the wavelength conversion member 10 may be an exposed surface on which the reflective multilayer film 30 is not formed, or a known functional layer such as an antireflection layer may be formed.

[0135] Next, as an example of a process for forming the reflective multilayer film 30 , a method of alternately forming the above-mentioned high-refractive-index inorganic film material and low-refractive-index inorganic film material on one surface 21 of the phosphor plate 20 can be used.

[0136] For example, the reflective multilayer film 30 can be formed by alternately forming titanium oxide (a material for a high-refractive-index inorganic film) and silicon oxide (a material for a low-refractive-index inorganic film) and controlling the film thickness of each layer.

[0137] The film can be formed by a known method, and vacuum deposition such as heating deposition, ion-assisted deposition, and ion plating deposition, DC sputtering, ion beam sputtering, and magnetron sputtering can be used.

[0138] The light emitting device of this embodiment will be described.

[0139] Figure 2 It is a cross-sectional view schematically showing a structural example of the light emitting device 1 .

[0140] The light emitting device 1 includes the wavelength conversion member 10 and the light emitting element 3 (light source).

[0141] A blue LED emitting blue light such as a group III nitride semiconductor light emitting element can be used as the light emitting element 3. The group III nitride semiconductor light emitting element is composed of a group III nitride semiconductor such as AlGaN, GaN, or InAlGaN-based materials, and includes an n-layer, a light emitting layer, and a p-layer.

[0142] The light emitting element 3 mounted on the substrate 2 only needs to be disposed on the side of the wavelength conversion member 10 on which the reflective multilayer film 30 is formed, and the light emitting element 3 can be arranged in direct contact with the wavelength conversion member 10, or with a space therebetween. The space can be filled with a light-transmitting member or the like, or can be composed of a gap.

[0143] The substrate 2 may have various structures depending on the application, and may have, for example, a structure for housing the light emitting element 3. The wavelength conversion member 10 is disposed in the opening of the housing structure.

[0144] The material of the substrate 2 is not particularly limited, and ceramics can be used.

[0145] The electrical connection between the substrate 2 and the light emitting element 3 may be a flip chip type or a wire bonding type.

[0146] The embodiments of the present invention are described above, but these are examples of the present invention, and various structures other than the above can be adopted. In addition, the present invention is not limited to the above embodiments, and modifications and improvements within the scope of achieving the purpose of the present invention are included in the present invention.

[0147] Example

[0148] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited at all to the descriptions of these Examples.

[0149] <Production of spinel phosphor plate>

[0150] The phosphor plate was manufactured through the following process.

[0151] (1) A Ca-α-type sialon phosphor (ALONBRIGHT YL-600B, manufactured by Denka Company Limited, median diameter 15 μm) and spinel raw material powders of MgO (MgO: magnesium oxide manufactured by FUJIFILM Wako Pure Chemical Corporation, average particle size 0.2 μm, purity 99.9%) and Al2O3 (manufactured by Sumitomo Chemical Co., Ltd., AA-03, BET specific surface area: 5.2 m 2 / g), wet-mixed in an ethanol solvent for 30 minutes using a polyethylene pot and an alumina ball, and the obtained slurry was filtered to remove the solvent and then dried. Then, the mixed raw materials were passed through a nylon mesh sieve with a mesh size of 75 μm to decompose the agglomerates, and a raw material mixed powder was obtained.

[0152] When all the spinel raw material powders reacted to become spinel, the amount of the α-sialon phosphor was adjusted to be 30 volume % in the phosphor plate (the remainder was MgO and Al 2 O 3 ).

[0153] The ratio of MgO to Al 2 O 3 in the spinel raw material powder was set to MgO:Al 2 O 3 = 21:79 in terms of mass ratio (Mg:Al = 1:3 in terms of molar amount).

[0154] (2) Fill the raw material mixed powder into the hot press fixture. Specifically, about 10 g of the raw material mixed powder is filled into a carbon mold with an inner diameter of 30 mm and a carbon lower punch. Then, a carbon upper punch is set to clamp the raw material powder.

[0155] A carbon sheet (GRAFOIL, manufactured by GraTech) with a thickness of 0.127 mm was placed between the raw material mixed powder and the carbon jig to prevent adhesion.

[0156] (3) A hot pressing fixture filled with the raw material mixed powder was placed in a multi-purpose high temperature furnace (Himulti-5000 manufactured by FUJIDENPO KOGYO CO., LTD.) equipped with a carbon heater. The furnace was evacuated until it became less than 0.1 Pa, and the upper and lower punches were pressurized at a pressure of 55 MPa while maintaining the reduced pressure. While maintaining the pressurized state, the temperature was raised to 1600°C at a rate of 5°C per minute. After reaching 1600°C, the heating was stopped, and the mixture was gradually cooled to room temperature, and the pressure was removed.

[0157] Then, the fired product with an outer diameter of 30 mm was collected, and the surface, back surface, and side surfaces were ground using a surface grinder and a cylindrical grinder, thereby obtaining a disk-shaped spinel phosphor plate with a thickness of 2.5 to 3.0 mm and a diameter of 25 mm.

[0158] (Examples 1-2, Comparative Examples 1-2)

[0159] The obtained spinel phosphor plate was ground using a surface grinder until the thickness reached about 1.0 mm, and then ground using a grinder until the thickness reached about 0.2 mm while adjusting the grinding speed and grinding time.

[0160] As the polishing conditions using the grinder, polishing using a finer-size abrasive grains or prolonging the polishing time or both were additionally performed in the order of Comparative Example 2, Comparative Example 1, Example 2, and Example 1.

[0161] [Comparative Example 3]

[0162] The obtained spinel-based phosphor plate was ground to a thickness of about 0.2 mm using a surface grinder and used.

[0163] <Production of Alumina-based Phosphor Plate>

[0164] 7.857 g of alumina powder (manufactured by Sumitomo Chemical Co., Ltd., AA-03, BET specific surface area: 5.2 m 2 / g) and 2.833g of Ca-α type sialon phosphor powder (Alon Bright YL-600B, manufactured by Denka Company Limited, with a median particle size of 15μm) were dry mixed using an agate mortar. The mixed raw materials were passed through a nylon mesh sieve with a mesh size of 75μm to decompose the agglomerates and obtain a raw material mixed powder. In addition, based on the true density of the raw materials (alumina: 3.97g / cm 3 , Ca-α-sialon phosphor: 3.34 g / cm 3 ) The calculated blending ratio is alumina: Ca-α type sialon phosphor = 70:30 vol%.

[0165] About 11 g of the raw material mixed powder was filled into a carbon mold with an inner diameter of 30 mm and a carbon lower punch, and a carbon upper punch was set to clamp the raw material powder. In addition, a carbon sheet (GRAFOIL manufactured by GraTech) with a thickness of 0.127 mm was set to prevent the raw material mixed powder from sticking to the carbon fixture.

[0166] The hot pressing fixture filled with the raw material mixed powder is set in a multifunctional high-temperature furnace (manufactured by FUJIDENPO KOGYO CO., LTD., Himulti-5000) with a carbon heater. The furnace is evacuated until it becomes less than 0.1Pa, and the upper and lower punches are pressurized at a pressure of 55MPa while maintaining the reduced pressure. While maintaining the pressurized state, the temperature is raised to 1600℃ at a rate of 5℃ per minute. After reaching 1600℃, the heating is stopped immediately, and the mixture is gradually cooled to room temperature, and the pressure is removed (sintering process).

[0167] Then, the fired product with an outer diameter of 30 mm was collected, and the surface, back surface, and side surfaces were ground using a surface grinder and a cylindrical grinder, thereby obtaining a disk-shaped alumina-based phosphor plate with a thickness of 2.5 to 3.0 mm and a diameter of 25 mm.

[0168] (Example 3, Comparative Example 4)

[0169] The obtained spinel phosphor plate was ground using a surface grinder until the thickness reached about 1.0 mm, and then ground using a grinder to a thickness of about 0.2 mm while setting the grinding speed to a constant and adjusting the abrasive grain size or grinding time.

[0170] As the polishing conditions using the grinder, polishing using a finer-size abrasive grains or extending the polishing time or both were performed in the order of Comparative Example 4 and Example 3.

[0171] [Comparative Example 5]

[0172] The obtained spinel-based phosphor plate was ground to a thickness of about 0.2 mm using a surface grinder and used.

[0173] The Rsm of one side (the surface on which the reflective multilayer film was formed) of the phosphor plate obtained in each example and each comparative example was measured using a surface roughness measuring instrument (SJ-400 manufactured by Mitutoyo Corporation) in accordance with JIS B 0031: 1994. The results are shown in Table 1. In addition, "-" in Table 1 means that the measurement was not performed.

[0174] Table 1

[0175] Rsm(μm) Example 1 12.1 Example 2 47.2 Comparative Example 1 - Comparative Example 2 - Comparative Example 3 67.1 Example 3 47.2 Comparative Example 4 - Comparative Example 5 65.4

[0176] <Film formation of reflective multilayer film>

[0177] On one side of the phosphor plate in each of the obtained embodiments and comparative examples (the surface on which the reflective multilayer film is formed), titanium oxide (TiO2) and silicon oxide (SiO2) are alternately vacuum-deposited under the same film-forming conditions to form a reflective multilayer film with a total of 28 layers (total thickness of approximately 2.6 μm).

[0178] Through the above operations, a wavelength conversion member in which a reflective multilayer film is formed on one surface of a phosphor plate is manufactured.

[0179] Figure 3 (a) shows the SEM image of Example 2, Figure 3 (b) shows a SEM image of Comparative Example 3. Figure 3 In the figure, gray represents SiO2 and black represents TiO2.

[0180] In addition, a STEM cross-sectional image was obtained for the reflective multilayer film formed on the phosphor plate of Example 2, and the brightness was plotted using the image, and the thickness of each layer was measured based on the produced map.

[0181] From the results in Table 2, it can be seen that the reflective multilayer film of Example 2 has a stacked structure in which an asymmetric stacked structure, a periodic stacked structure, and an asymmetric stacked structure are arranged in sequence. The same stacked structure was also confirmed in the reflective multilayer films on the phosphor plates of Examples 1 and 3.

[0182]

[0183] <Color tone>

[0184] In the wavelength conversion components of each embodiment and each comparative example, the color tone of the surface of the reflective multilayer film on one side of the phosphor plate (reflective multilayer film surface) and the surface on the other side of the phosphor plate (exposed surface) were measured using an ultraviolet visible spectrophotometer (V-550) manufactured by JASCO Corporation equipped with an integrating sphere device (ISV-469). Background correction was performed using a standard white plate (Spectralon manufactured by Labsphere).

[0185] A wavelength conversion component was set up, and the measurement surface (the surface of the reflective multilayer film or the exposed surface of the phosphor plate) was measured in the wavelength range of 300 to 850 nm, and the hue (L * 、a * 、b * ). The results are shown in Table 3.

[0186] Table 3

[0187]

[0188] The obtained wavelength conversion member was evaluated with respect to the following evaluation items.

[0189] <Diffuse reflectivity>

[0190] In the wavelength conversion components of each embodiment and each comparative example, the diffuse reflectance spectrum at a wavelength of 250 nm to 850 nm was measured for the formation surface of the reflective multilayer film using an ultraviolet-visible-infrared spectrophotometer (JASCO Corporation, V-550) and a standard white plate (Labsphere, Spectralon) after base correction. The diffuse reflectance (%) at each wavelength (450 nm and 600 nm) was calculated based on the obtained diffuse reflectance spectrum. The results are shown in Table 4.

[0191] Table 4

[0192]

[0193] <Evaluation of optical properties>

[0194] In the wavelength conversion member of each example and each comparative example, the emission intensity before the formation of the reflective multilayer film and the emission intensity after the formation of the reflective multilayer film were measured.

[0195] Specifically, a fixture is prepared to accommodate an excitation light source (blue LED: peak wavelength is 450nm) in an opening, and is configured so that one side of the phosphor plate (the exposed surface or the surface where the reflective multilayer film is formed) faces the excitation light source, and the phosphor plate is set in a manner to block the opening of the fixture.

[0196] Then, using a full-beam measurement system (Half Moon / φ1000mm integrating sphere system, manufactured by Otsuka Electronics Co., Ltd.), after applying current to the excitation light source and maintaining it for 90 seconds, the luminescence spectrum of light emitted from the other side of the phosphor plate (the side opposite to the irradiation surface of the excitation light) was measured.

[0197] Table 5 shows the peak intensity of the emission spectrum as a relative value when the emission intensity was normalized by setting the emission intensity before forming the reflective multilayer film of Comparative Example 3 to 1.0.

[0198] Table 5

[0199] PL intensity (relative value) Before the formation of reflective multilayer film After the reflective multilayer film is formed B / A Example 1 1.06 1.45 1.37 Example 2 1.03 1.21 1.18 Comparative Example 1 1.01 0.92 0.91 Comparative Example 2 1.01 0.87 0.86 Comparative Example 3 1.00 0.81 0.81 Example 3 1.03 1.25 1.21 Comparative Example 4 1.02 0.87 0.85 Comparative Example 5 1.02 0.81 0.79

[0200] The wavelength conversion members of Examples 1 to 3 showed results of excellent emission intensity because the fluorescence intensity (relative value) after the reflective multilayer film was formed on the phosphor plate was improved compared with Comparative Examples 1 to 5.

[0201] This application claims priority based on Japanese patent application No. 2022-149926, filed on September 21, 2022, and all the disclosed contents are incorporated into this specification.

[0202] Explanation of symbols

[0203] 1- Light emitting device,

[0204] 2- substrate,

[0205] 3- Light-emitting element,

[0206] 10- wavelength conversion component,

[0207] 20-Phosphor plate,

[0208] 21- one side,

[0209] 22- The other side,

[0210] 30-Reflective multilayer film.

Claims

1. A wavelength conversion component, comprising: A phosphor plate comprising an inorganic matrix and a phosphor dispersed in the inorganic matrix, and a reflective multilayer film formed on a surface of one side of the phosphor plate and formed by laminating a plurality of inorganic films having different refractive indices; The wavelength conversion component is composed of: When measured according to JIS Z 8781-4, the L * a * b * In the chromaticity coordinates, a * The value is greater than -20 and less than 0, and / or b * The value satisfies 20 or more and 60 or less.

2. The wavelength conversion component according to claim 1, wherein: In the diffuse reflection spectrum of one surface of the phosphor plate on which the reflective multilayer film is formed, the diffuse reflectance at 450 nm is 35% or less.

3. The wavelength conversion component according to claim 1 or 2, wherein: In the diffuse reflection spectrum of one surface side of the phosphor plate on which the reflective multilayer film is formed, the diffuse reflectance at 600 nm is 82% or more.

4. The wavelength conversion component according to claim 1 or 2, wherein: When blue excitation light is irradiated from one side where the reflective multilayer film is formed, the peak wavelength of the emission spectrum detected from the other side of the phosphor plate opposite to the reflective multilayer film is within the range of 580 nm to 620 nm.

5. The wavelength conversion component according to claim 1 or 2, wherein: On the surface of one side of the phosphor plate, Rsm measured in accordance with JIS B 0031:1994 is 60 μm or less.

6. The wavelength conversion component according to claim 1 or 2, wherein: The reflective multilayer film has a periodic stacked structure in which at least one of a high-refractive-index inorganic film and a low-refractive-index inorganic film is stacked with substantially the same thickness.

7. The wavelength conversion component according to claim 6, wherein: The reflective multilayer film includes an asymmetric stacked structure disposed adjacent to the periodic stacked structure and in which at least one of the high refractive index inorganic film and the low refractive index inorganic film is stacked with different thicknesses.

8. The wavelength conversion component according to claim 1 or 2, wherein: The phosphor includes any one of an α-sialon phosphor, a (Ba, Sr, Ca) 2 Si 5 N 8 phosphor, a mixture of a YAG phosphor and a SCASN phosphor, and a SCASN phosphor.

9. The wavelength conversion component according to claim 1 or 2, wherein: The inorganic base material contains alumina or a spinel compound. 10 . A light emitting device comprising the wavelength conversion member according to claim 1 or 2 and a light source. The lighting device according to claim 10 , which is a direction indicator.

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