Light emitting device

Abstract

To provide a light emitting device which emits light of high luminous flux.SOLUTION: The light-emitting device 100 includes the light-emitting elements 20 having peak emission wavelengths in the range of 380nm or more and 500nm or less and the wavelength-converting members 30 disposed on the light-emitting side of the light-emitting elements 20 and having light-emitting surfaces. And a light-transmissive thin film 32 disposed on the light emitting side of the ceramic composite 31 and having a refraction index smaller than the refraction index of the ceramic composite 31, wherein the light-transmissive thin film 32 is a single layer having a physical thickness in a range of 510nm or more and 570nm or less, and the light-transmissive thin film 32 is a single layer having a physical thickness in a range of 82nm or more and 140nm or less. The light-transmissive thin film 32 is made of a fluoride containing at least one element selected from the group consisting of an alkali metal element, an alkaline earth metal element, and a group 13 metal element.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light emitting device. [Background technology]

[0002] Light-emitting devices are known that include a light-emitting diode (LED) or a laser diode (LD) and a wavelength conversion member containing a phosphor that converts the wavelength of light emitted from the LED or LD light-emitting element. Such light-emitting devices are used, for example, as light sources for in-vehicle lighting, general lighting, backlights for liquid crystal display devices, projectors, etc.

[0003] For example, Patent Document 1 discloses a light-emitting device that has a phosphor made of bulk crystal and dissipates heat from the phosphor through a heat sink. Patent Document 1 also discloses that an anti-reflection layer that prevents reflection of excitation light is formed on the excitation light incident surface of the bulk crystal phosphor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-186882 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for light emitting devices using ceramic composites containing inorganic phosphors and inorganic oxides that emit light with even higher luminous flux. In view of the above, an object of one embodiment of the present invention is to provide a light-emitting device that emits light with a high luminous flux. [Means for solving the problem]

[0006] A first aspect is a light emitting device including: a light emitting element having an emission peak wavelength in the range of 380 nm or more and 500 nm or less; and a wavelength conversion member having a light emitting surface and arranged on the light emission side of the light emitting element, wherein the wavelength conversion member includes a ceramic composite containing an inorganic phosphor having an emission peak wavelength in the range of 510 nm or more and 570 nm or less and an inorganic oxide; and a translucent thin film arranged on the light emission side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, wherein the physical film thickness of the translucent thin film is a single layer in the range of 82 nm or more and 140 nm or less, and the translucent thin film is made of a fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements.

[0007] A second aspect is a light emitting device including: a light emitting element having an emission peak wavelength in the range of 380 nm to 500 nm; and a wavelength conversion member having a light emitting surface and disposed on the light emission side of the light emitting element, wherein the wavelength conversion member includes a ceramic composite containing an inorganic phosphor and an inorganic oxide; and a translucent thin film disposed on the light emission side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, wherein the translucent thin film is a single layer made of fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements, and wherein the L value derived from the following formula (2), which is the ratio of the physical thickness L1 of the translucent thin film to the optical thickness L0 derived from the following formula (1) of the translucent thin film, is in the range of 0.82 to 1.41. L0 = emission peak wavelength (λ) (nm) of inorganic phosphor ÷ (4 × refractive index of transparent thin film) (1) L=Physical thickness of transparent thin film L1 (nm) ÷ L0 (2)

[0008] A third aspect is a light emitting device including: a light emitting element having an emission peak wavelength in the range of 380 nm or more and 500 nm or less; and a wavelength conversion member having a light emitting surface and arranged on the light emission side of the light emitting element, wherein the wavelength conversion member includes a ceramic composite containing an inorganic phosphor having an emission peak wavelength in the range of 510 nm or more and 570 nm or less and an inorganic oxide; and a translucent thin film arranged on the light emission side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, wherein the physical film thickness of the translucent thin film is a single layer in the range of 250 nm or more and 330 nm or less, and the translucent thin film is made of silicon dioxide or fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements.

[0009] A fourth aspect is a light emitting device including: a light emitting element having an emission peak wavelength in the range of 380 nm to 500 nm; and a wavelength conversion member having a light emitting surface and disposed on the light emission side of the light emitting element, wherein the wavelength conversion member includes a ceramic composite containing an inorganic phosphor and an inorganic oxide; and a translucent thin film disposed on the light emission side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, wherein the translucent thin film is a single layer made of silicon dioxide or fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements, and wherein the value L derived from formula (2), which is the ratio of the physical film thickness L1 of the translucent thin film to the optical film thickness L0 derived from formula (1) of the translucent thin film, is in the range of 2.5 to 3.5.

[0010] A fifth aspect is a light emitting device including: a light emitting element having an emission peak wavelength in the range of 380 nm to 500 nm; and a wavelength conversion member having a light emitting surface and disposed on the light emission side of the light emitting element, wherein the wavelength conversion member includes a ceramic composite containing an inorganic phosphor having an emission peak wavelength in the range of 510 nm to 570 nm and an inorganic oxide; and a translucent thin film disposed on the light emission side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, wherein the translucent thin film is made of silicon dioxide or fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements, and the light emitting device emits light that satisfies at least one of the following: a first transmittance difference T1 calculated based on the following formula (3) is in the range of 0% to 25%; and a second transmittance difference T2 calculated based on the following formula (4) is in the range of -3% to 10%. T1=T C-60 -T P-60 -(T C-0 -T P-0 ) (3) T2=T C-30 -T P-30 -(T C-0 -T P-0 ) (4) (In the above formula (3), T C-60 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element at a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees, and T P-60 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees. C-30 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element at a directivity angle of plus 30 degrees and a directivity angle of minus 30 degrees, and T P-30 is the average value of the transmittance of light transmitted through the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of plus 30 degrees and a directivity angle of minus 30 degrees. C-0is the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element with a directivity angle of 0 degrees, and T P-0 is the transmittance of light transmitted from the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of 0 degrees. Here, the directivity angle of 0 degrees is the angle perpendicular to the light-emitting surface, the directivity angle of +60 degrees and the directivity angle of -60 degrees are angles of +60 degrees and -60 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center, and the directivity angle of +30 degrees and the directivity angle of -30 degrees are angles of +30 degrees and -30 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center.)

[0011] A sixth aspect is a light emitting device including a light emitting element having an emission peak wavelength in the range of 380 nm to 500 nm, and a wavelength converting member having a light emitting surface and disposed on the light emitting side of the light emitting element, wherein the wavelength converting member includes a ceramic composite containing an inorganic phosphor having an emission peak wavelength in the range of 510 nm to 570 nm and an inorganic oxide, and a translucent thin film disposed on the light emitting side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, and the translucent thin film is an alkali metal The light emitting device includes at least two layers: a first layer made of silicon dioxide or fluoride containing at least one element selected from the group consisting of elements, alkaline earth metal elements, and Group 13 metal elements; and a second layer made of an oxide containing at least one element selected from the group consisting of aluminum, niobium, tantalum, titanium, and zirconium; and when there are two or more layers, the first and second layers are alternately stacked, and the light emitting device emits light that satisfies the following requirement: a third transmittance difference T3 calculated based on the following formula (5) is within the range of 0% or more and 20% or less. T3=T C-45 -T P-45 -(T C-0 -T P-0 ) (5) (In the above formula (5), T C-45 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element at a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees, and TP-45 is the average value of the transmittance of light transmitted through the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees. C-0 is the transmittance of light transmitted through the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the light-emitting element with a directivity angle of 0 degrees, and T P-0 is the transmittance of light transmitted from the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of 0 degrees. Here, the directivity angle of 0 degrees is the angle perpendicular to the light-emitting surface, and the directivity angle of +45 degrees and the directivity angle of -45 degrees are angles of +45 degrees and -45 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center.)

[0012] A seventh aspect is a light emitting device including a light emitting element having an emission peak wavelength in the range of 380 nm to 500 nm, and a wavelength converting member having a light emitting surface and disposed on the light emission side of the light emitting element, wherein the wavelength converting member includes a ceramic composite containing an inorganic phosphor having an emission peak wavelength in the range of 510 nm to 570 nm and an inorganic oxide, and a light transmissive thin film disposed on the light emission side of the ceramic composite and having a refractive index smaller than that of the ceramic composite, wherein the light transmissive thin film is a single layer made of silicon dioxide or fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements, and wherein the chromaticity coordinates in the CIE 1931 chromaticity diagram are: x-coordinate x0 of the emission color of the light emitting device at a directivity angle of 0 degrees; and x-coordinate x1 which is an average value of the x-coordinates of the emission color of the light emitting device at directivity angles of +60 degrees and -60 degrees, which are angles from a perpendicular to the light emitting surface toward the light emitting surface at a directivity angle of 0 degrees. 60 The absolute value of the difference Δx between the light emitting element and the light emitting element is 0.012 or less. [Effects of the Invention]

[0013] According to one embodiment of the present invention, a light-emitting device that emits light with a high luminous flux can be provided. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic plan view of a light emitting device. [Figure 2] FIG. 2 is a schematic cross-sectional view of the light emitting device. [Figure 3] FIG. 3 is an enlarged schematic view of a part of the wavelength conversion member. [Figure 4] FIG. 4 is an image diagram showing the directivity angle of a light emitting device. [Figure 5] FIG. 5 is a diagram showing the relationship between the wavelength of light transmitted through a light-emitting device having a light-transmitting thin film and the transmittance for a directivity angle of 0 degrees, a directivity angle of plus 60 degrees, and a directivity angle of minus 60 degrees. [Figure 6] FIG. 6 is an image diagram showing a schematic enlarged view of a part of the wavelength conversion member. [Figure 7] FIG. 7 is a graph showing the relationship between the physical film thickness of the light-transmitting thin film and the relative luminous flux. [Figure 8] FIG. 8 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example A-4 and the light emitting device according to Comparative Example a'-1. [Figure 9] FIG. 9 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example B-6 and the light emitting device according to Comparative Example b'-1. [Figure 10] FIG. 10 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example C-8 and the light emitting device according to Comparative Example c′-1. [Figure 11] FIG. 11 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example D-2 and the light emitting device according to Comparative Example d′-1. [Figure 12] FIG. 12 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example C-6 and the light emitting device according to Comparative Example c′-1. [Figure 13]FIG. 13 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example C-7 and the light emitting device according to Comparative Example c′-1. [Figure 14] FIG. 14 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity of light emitted by the light emitting device according to Example C-9 and the light emitting device according to Comparative Example c′-1. [Figure 15] FIG. 15 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Example C-11 and the light emitting device according to Comparative Example c′-1. [Figure 16] FIG. 16 is a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity between the light emitted by the light emitting device according to Comparative Example c′-1 and the light emitting device according to Comparative Example c′-4. DETAILED DESCRIPTION OF THE INVENTION

[0015] The light emitting device will be described below based on an embodiment. However, the embodiment shown below is an example for embodying the technical concept of the present invention, and the present invention is not limited to the light emitting device described below. The relationship between color names and chromaticity coordinates, and the relationship between light wavelength ranges and color names of monochromatic light, conforms to JIS Z8110.

[0016] Light-emitting device The light emitting device includes a light emitting element having an emission peak wavelength in the range of 380 nm to 500 nm, and a wavelength converting member having a light emitting surface and arranged on the light emitting side of the light emitting element, the wavelength converting member including a ceramic composite containing an inorganic phosphor and an inorganic oxide, and a light-transmitting thin film arranged on the light emitting side of the ceramic composite and having a refractive index smaller than that of the ceramic composite. An example of the light emitting device will be described below.

[0017] FIG. 1 shows an example of a light-emitting device. It is a schematic plan view of the light-emitting device 100, and FIG. 2 is a schematic cross-sectional view of the light-emitting device 100 taken along line II-II' in FIG. 1. The light-emitting device 100 includes a light-emitting element 20 formed of an LED or LD, a ceramic composite 31 that emits light upon excitation by light from the light-emitting element 20, and a wavelength conversion member 30 including a translucent thin film 32 disposed on the light-emitting side of the ceramic composite 31. The light-emitting element 20 is flip-chip mounted on a substrate 10 via bumps that are conductive members 60. The wavelength conversion member 30 includes the ceramic composite 31 disposed on the light-emitting surface of the light-emitting element 20 via an adhesive layer 40. The ceramic composite 31 serves as an incident surface 31a through which light enters from the light-emitting element 20, and the translucent thin film 32 serves as a light-emitting surface 31b. The translucent thin film 32 is disposed on the emission side of the ceramic composite 31. The light-emitting element 20 and the wavelength conversion member 30 have their side surfaces covered with a light-reflecting covering member 50. The light emitting element 20 receives a supply of power from outside the light emitting device 100 via wiring and a conductive member 60 formed on the substrate 10, causing the light emitting device 100 to emit light. The light emitting device 100 may include a semiconductor element 70, such as a protective element, for protecting the light emitting element 20 from damage due to application of excessive voltage. The covering member 50 is provided, for example, to cover the semiconductor element 70. The covering member 50 may include a resin 51 and at least one additive 52 selected from the group consisting of a colorant, a phosphor, and a filler. Each component used in the light emitting device will be described below. For details, see, for example, the disclosure of JP 2014-112635 A.

[0018] Light-emitting element The light emitting element may be, for example, an LED chip or an LD chip, which is a semiconductor light emitting element using a nitride semiconductor.

[0019] The light-emitting element preferably has an emission peak wavelength within the range of 380 nm or more and 500 nm or less, more preferably within the range of 390 nm or more and 495 nm or less, still more preferably within the range of 400 nm or more and 490 nm or less, and particularly preferably within the range of 420 nm or more and 490 nm or less. The light-emitting element is provided with a p electrode and an n electrode. The p electrode and the n electrode of the light-emitting element may be formed on the same side surface of the light-emitting element, or may be provided on different side surfaces. The light-emitting element may be flip-chip mounted.

[0020] Wavelength conversion member Ceramic composite The ceramic composite includes an inorganic phosphor and an inorganic oxide. The inorganic phosphor emits fluorescence having an emission peak wavelength within the range of 510 nm or more and 570 nm or less by the light from a light-emitting element having an emission peak wavelength within the range of 380 nm or more and 500 nm or less.

[0021] Inorganic phosphor The inorganic phosphor only needs to emit fluorescence having an emission peak wavelength within the range of 510 nm or more and 570 nm or less, and preferably contains at least one phosphor selected from the group consisting of rare earth aluminate phosphors, silicate phosphors, and β-sialon phosphors, and more preferably contains a rare earth aluminate phosphor.

[0022] The rare earth aluminate phosphor preferably has a composition represented by the following formula (I). (Ln 1 1-a Ce a )3(Al c Ga b )5O 12 (I) (In the above formula (I), Ln 1 is at least one first rare earth element selected from the group consisting of Y, Gd, Lu, and Tb, and a, b, and c are numbers satisfying 0 < a ≤ 0.22, 0 ≤ b ≤ 0.4, 0 < c ≤ 1.1, and 0.9 ≤ b + c ≤ 1.1.)

[0023] The first rare earth element Ln contained in the rare earth aluminate phosphor 1 may contain two or more elements selected from the group consisting of Y, Lu, Gd, and Tb. The first rare earth element Ln 1 may be at least one selected from the group consisting of Y, Lu, and Gd. The first rare earth element Ln 1 may be Y and Gd, or may be Y and Lu. In the rare earth aluminate phosphor, two or more of the first rare earth elements Ln 1 are contained. When the first rare earth element Ln 1 is Y and Gd, in the composition of the rare earth aluminate phosphor, the molar ratio of Y and Gd (Y:Gd) is preferably in the range of 99.5:0.5 to 70:30, may be within the range of 99:1 to 80:20, or may be within the range of 99:1 to 90:10.

[0024] The silicate phosphor preferably has a composition represented by the following formula (II). Ca d Eu e Mg f Si4O g Cl h (II) (In formula (II), d, e, f, g, and h are numbers that satisfy 7.0 ≦ d ≦ 7.94, 0.01 ≦ e ≦ 1.0, 7.70 ≦ d + e ≦ 7.95, 0.9 ≦ f ≦ 1.1, 15.6 ≦ g ≦ 16.1, and 1.90 < h ≦ 2.00, respectively.)

[0025] The β-sialon phosphor preferably has a composition represented by the following formula (III). Si 6-z Al z O z N 8-z :Eu (0 < z ≦ 4.2) (III)

[0026] Inorganic oxide The inorganic oxide contains at least Al and at least one second rare earth element Ln selected from the group consisting of Y, Gd, Tb, and Lu 2The inorganic oxides used as raw materials for forming the ceramic composite include aluminum oxide (Al2O3), yttrium oxide (YO3), gadolinium oxide (Gd2O3), terbium oxide (Tb4O7), and lutetium oxide (Lu2O3). At least one second rare earth element Ln selected from the group consisting of Y, Gd, Tb, and Lu may be included. 2 and the second rare earth element Ln 2 The composite oxide may contain other elements. Examples of the composite oxide include yttrium aluminum perovskite (YAlO3:YAP) and yttrium aluminum garnet (Y3Al5O 12 :YAG).

[0027] The content of the inorganic phosphor in the ceramic composite may be, for example, in the range of 5% by mass to 98% by mass, or in the range of 10% by mass to 95% by mass, based on the total mass of the ceramic composite. The content of the inorganic phosphor contained in the ceramic composite may be any content that allows light having the desired emission peak wavelength to be obtained.

[0028] The thickness of the ceramic composite may be in the range of 50 μm to 500 μm, in the range of 60 μm to 450 μm, or in the range of 70 μm to 400 μm. The size of the ceramic composite used as the wavelength conversion member may be any size as long as it is large enough to cover the entire light extraction surface of the light emitting element.

[0029] The refractive index r1 of the ceramic composite is preferably in the range of 1.76 to 1.85, and may be in the range of 1.77 to 1.83. If the refractive index r1 of the ceramic composite is within this range, by placing a translucent thin film having a refractive index smaller than that of the ceramic composite on the light output side, it is possible to reduce reflection at the wavelength conversion member and increase the luminous flux of the light emitting device. When the inorganic phosphor contained in the ceramic composite is a rare earth aluminate phosphor, the refractive index r1 of the ceramic composite can be in the range of 1.76 to 1.85.

[0030] The refractive index r1 of the ceramic composite can be calculated by the sum of the product of the content of the inorganic phosphor in the ceramic composite and the refractive index of the inorganic phosphor, and the product of the content of the inorganic oxide in the ceramic composite and the refractive index of the inorganic oxide. Specifically, it can be calculated based on the following formula (6). When the ceramic composite contains two or more inorganic oxides, the refractive index of the ceramic composite can be calculated from the content of each inorganic oxide and the refractive index of that inorganic oxide.

[0031]

number

[0032] The volume percentage of the inorganic phosphor in the ceramic composite can be calculated based on the following formulas (7) and (8). The volume percentage of the inorganic oxide in the ceramic composite can be calculated based on the following formula (9).

[0033]

number

[0034]

number

[0035]

number

[0036] Manufacturing method of ceramic composite The ceramic composite can be produced by molding a raw material mixture containing an inorganic phosphor and an inorganic oxide using a press molding method such as die pressing and / or cold isostatic pressing (CIP), subjecting the resulting molded body to primary firing to obtain a sintered body, and then, if necessary, subjecting the sintered body to secondary firing using a method such as hot isostatic pressing (HIP). Annealing may be performed after secondary firing. The temperature for primary firing of the molded body may be in the range of 1550°C to 2000°C. The temperature for secondary firing of the sintered body may be in the range of 1500°C to 2000°C. The annealing temperature is lower than the firing temperatures for primary and secondary firings and may be in the range of 1000°C to 1500°C. For details of the method for producing the ceramic composite, please refer to the disclosure of Japanese Patent Application No. 2020-113289.

[0037] Translucent thin film The light-transmitting thin film is disposed on the light-emitting side of the ceramic composite, and has a refractive index smaller than that of the ceramic composite.

[0038] The light-emitting device of the first embodiment includes a wavelength conversion member including a single-layer translucent thin film with a physical thickness L1 in the range of 82 nm to 140 nm. When the wavelength conversion member includes a single-layer translucent thin film with a physical thickness L1 in the range of 82 nm to 140 nm on the light-emitting side of the ceramic composite, the reflection of light at the interface between the ceramic composite and the translucent thin film is canceled by the reflection of light at the interface between the translucent thin film and air, reducing reflection at each interface, resulting in a light-emitting device with a high luminous flux. The physical thickness L1 of the translucent thin film may be in the range of 83 nm to 130 nm, 84 nm to 125 nm, or 85 nm to 123 nm. The light-emitting device of the first embodiment may also include a translucent thin film with an L value (described later) in the range of 0.82 to 1.41.

[0039] The light-transmitting thin film is made of a fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and metal elements of Group 13. The fluoride is MgF2, CaF2, SrF2, AlF3, Na3AlF6, Na5Al3F14 , LiF, NaF, and KF. Fluorides include MgF2, CaF2, SrF2, AlF3, Na3AlF6, Na5Al3F 14 It is preferable that the transparent thin film contains at least one selected from the group consisting of NaF and LiF. The transparent thin film may be made of silicon dioxide (SiO2).

[0040] The reflection of light emitted from a light-emitting device will be described with reference to FIG. 3. FIG. 3 is a schematic enlarged view of a portion of a wavelength conversion member of a light-emitting device. The wavelength conversion member 30 includes a ceramic composite 31 and a light-transmitting thin film 32. The light emitted from the light-emitting device undergoes a first reflection at a first interface If1 between the ceramic composite 31 and the light-transmitting thin film 32, resulting in a first reflected wave Rw1, which is a sine wave having a first period. The light emitted from the light-emitting device undergoes a second reflection at a second interface If2 between the light-transmitting thin film 32 and air A, resulting in a second reflected wave Rw2, which is a sine wave having a second period. Because the refractive index r2 of the light-transmitting thin film 32 is smaller than the refractive index r1 of the ceramic composite 31, the phase of the second reflected wave Rw2 is reversed to the phase of the first reflected wave Rw1. When the first reflected wave Rw1 and the second reflected wave Rw2, which have opposite phases, are combined, the first reflected wave Rw1 and the second reflected wave Rw2 cancel each other out, reducing reflection within the wavelength conversion member 30 and allowing light with a higher luminous flux to be emitted from the light emitting device. In Fig. 3, z represents the optical axis.

[0041] A light-emitting device according to a second embodiment includes a wavelength conversion member including a single-layer light-transmitting thin film made of a fluoride, and the L value, which is the ratio of the physical thickness L1 of the light-transmitting thin film to the optical thickness L0 of the light-transmitting thin film calculated from the following formula (1), is in the range of 0.82 to 1.41. The light-emitting device according to the second embodiment may include a single-layer light-transmitting thin film made of a fluoride and having a physical thickness L1 of 82 to 140 nm. The thickness of a transparent thin film generally refers to its optical thickness (see page 21 of the revised and expanded first printing of "Fundamental Theory of Optics - Fresnel Coefficients, Characteristic Matrices" by Mitsunobu Kohiyama, published by Optronics Co., Ltd. on February 25, 2011). In this specification, the optical thickness L0 of the light-transmitting thin film refers to the value calculated from the following formula (1), and the physical thickness L1 of the light-transmitting thin film refers to the thickness measured from a cross-sectional SEM photograph or the like of the light-transmitting thin film. L0 = emission peak wavelength (λ) (nm) of inorganic phosphor ÷ (4 × refractive index of transparent thin film) (1) L=Physical thickness of transparent thin film L1 (nm) ÷ L0 (2)

[0042] The optical thickness L0 of the light-transmitting thin film is the value (nm) obtained by dividing the emission peak wavelength (λ) of the inorganic phosphor, which is the wavelength of light emitted from the light-transmitting thin film, by the product of 4, which is a numerical value that takes into account the phase at which the displacement (wave height) of the second reflected wave Rw2 reflected at the second interface between the light-transmitting thin film and air is highest (or lowest), and the refractive index of the light-transmitting thin film. In the above formula (1), the refractive index of the light-transmitting thin film is the refractive index of the material that makes up the light-transmitting thin film. For example, if the light-transmitting thin film is made of magnesium fluoride, the refractive index of the light-transmitting thin film is 1.38, which is the refractive index of magnesium fluoride. Also, for example, if the light-transmitting thin film is made of silicon dioxide, the refractive index of the light-transmitting thin film is 1.47, which is the refractive index of silicon dioxide.

[0043] The L value derived from the above formula (2) is the ratio (L1 / L0) of the physical film thickness L1 (nm) of the light-transmitting thin film to the optical film thickness L0 (nm) of the light-transmitting thin film derived from the above formula (1). When the L value derived from the above formula (2) approaches 1.0, as shown in Fig. 3, the second reflected wave Rw2 generated at the interface between the light-transmitting thin film and air and the first reflected wave Rw1 generated at the interface between the ceramic composite and the light-transmitting thin film approach a phase where they are in opposite phases, and the effect of the first reflected wave Rw1 and the second reflected wave Rw2 canceling each other out increases, reducing reflection within the wavelength conversion member and allowing light with a higher luminous flux to be emitted from the light-emitting device. In order to emit light with a high luminous flux, the light-transmitting thin film provided in the light-emitting device preferably has an L value in the range of 0.82 to 1.41, more preferably in the range of 0.82 to 1.4, even more preferably in the range of 0.85 to 1.3, and even more preferably in the range of 0.9 to 1.2.

[0044] A light-emitting device according to a third embodiment includes a wavelength conversion member including a translucent thin film, which is a single layer made of fluoride or silicon dioxide and has a physical film thickness L1 in the range of 250 nm to 330 nm. When the wavelength conversion member includes a translucent thin film, which is a single layer with a physical film thickness L1 in the range of 250 nm to 330 nm, on the light-emitting side of the ceramic composite, the change in chromaticity due to the directivity angle can be reduced, improving the orientation chromaticity characteristics. In this specification, when the light-emitting device is viewed from the normal direction, i.e., from a direction perpendicular to the light-emitting surface of the wavelength conversion member, which is the light-emitting surface of the light-emitting device, the directionality angle is referred to as 0 degrees. The direction of the directivity angle of 0 degrees is parallel to the optical axis of the light-emitting device. The angle inclined from the directivity angle of 0 degrees to the horizontal direction with respect to the light-emitting surface of the light-emitting device is referred to as the directivity angle θ degrees. The chromaticity of the emitted color for each directivity angle is sometimes referred to as "orientation chromaticity." Chromaticity refers to the x-coordinate value (sometimes written as "x value") and y-coordinate value (sometimes written as "y value") of the chromaticity coordinates on the CIE (International Commission on Illumination) 1931 chromaticity diagram. The difference in orientation chromaticity for each directivity angle is sometimes called "orientation chromaticity characteristics." The chromaticity coordinates (x0, y0) on the CIE chromaticity diagram at a directivity angle of 0 degrees are expressed, and the average values ​​of the x-coordinate and y-coordinate of the emitted color due to changes in the directivity angle plus θ degrees and the directivity angle minus θ degrees are expressed as the orientation chromaticity coordinates (x θ , y θ ) The plus θ degrees and minus θ degrees are specifically plus 30 degrees and minus 30 degrees, plus 45 degrees and minus 45 degrees, or plus 60 degrees and minus 60 degrees. "Good orientation chromaticity characteristics" means that the x-coordinate x0 at a directivity angle of 0 degrees and the light distribution chromaticity coordinate x at a directivity angle of θ degrees are θ This means that the difference Δx (absolute value) between the y coordinate y0 at a directivity angle of 0 degrees and the y coordinate y at a directivity angle of θ degrees is small, and the change in chromaticity is small even when the directivity angle is changed. θIt is also preferable that the difference Δy (absolute value) between the Δx and the Δy (hereinafter sometimes referred to as "orientation chromaticity difference Δy") is small. "Poor orientation chromaticity characteristics" means that the difference Δx in orientation chromaticity of the emitted color due to a change in the directivity angle is large, and a change in chromaticity occurs when the directivity angle changes. In order to improve the orientation chromaticity characteristics, the physical film thickness L1 of the translucent thin film may be in the range of 250 nm to 330 nm, or in the range of 250 nm to 320 nm, or in the range of 260 nm to 320 nm. The light-emitting device of the third embodiment may be provided with a translucent thin film having an L value (described later) in the range of 2.5 to 3.5.

[0045] 4 is an image diagram showing the directivity angle of the light emitting device 100. When the light emitting device 100 is viewed from the normal direction, i.e., when viewed from a directivity angle of 0° (θ=0° in FIG. 4), which is a direction parallel to the optical axis z, the light emitting surface of the light emitting device tends to easily emit light in the range of 380 nm to 500 nm, in which the emission peak wavelength of the light emitting element exists. On the other hand, the light emitting device 100 tends to easily emit light in the range of 510 nm to 570 nm, in which the emission peak wavelength of the inorganic phosphor exists, as the angle of inclination from the light emitting surface of the light emitting device to the horizontal direction increases, i.e., as the directivity angle approaches the directivity angle plus 90° (θ=+90° in FIG. 4) or the directivity angle minus 90° (θ=−90° in FIG. 4). Here, a directivity angle of plus θ degrees (+θ°) is an angle inclined by θ degrees horizontally from the light-emitting surface of the light-emitting device, with a directivity angle of 0 degrees (0°) as the center, and a directivity angle of minus θ degrees (-θ°) is an angle inclined by θ degrees horizontally from the light-emitting surface of the light-emitting device, on the opposite side of a line centered on a directivity angle of 0 degrees from a directivity angle of plus θ degrees (+θ°).

[0046] The light emitting device includes a wavelength conversion member including a single-layer translucent thin film made of fluoride or silicon dioxide. When the translucent thin film satisfies certain conditions, the transmittance of the light emitted by the inorganic phosphor (e.g., light emitted with a peak emission wavelength of around 550 nm) is higher than that of the light emitted by the light emitting element (e.g., light emitted with a peak emission wavelength of around 450 nm) in a direction parallel to the optical axis z, i.e., a direction at a directivity angle of 0 degrees (θ=0° in FIG. 4). Compared to when the wavelength conversion member does not include a translucent thin film, the transmittance of the wavelength conversion member is higher, and the light emitted by the inorganic phosphor contained in the wavelength conversion member is more likely to pass through the translucent thin film. Furthermore, when the wavelength conversion member includes a translucent thin film, the light emitted by the inorganic phosphor tends to be more easily emitted in a direction at a directivity angle of 0 degrees (θ=0° in FIG. 4) than when the wavelength conversion member does not include a translucent thin film. FIG. 5 is a diagram showing the transmittance when the wavelength conversion member includes a specific translucent thin film. As shown in FIG. 5, when the directivity angle is 0 degrees (0°), and the wavelength conversion member includes a specific translucent thin film, the transmittance of the wavelength conversion member including the translucent thin film is higher at wavelengths exceeding 470 nm than when the directivity angle is plus 60 degrees (+60°) or minus 60 degrees (-60°), and the emitted light from the inorganic phosphor is more likely to be emitted. "0°" in FIG. 5 means a directivity angle of 0 degrees (0°). "60°" in FIG. 5 means a directivity angle of plus 60 degrees or minus 60 degrees (+60° or -60°). The transmittance can be measured in the same manner as the transmittance described below. FIG. 5 shows a case where a translucent thin film made of magnesium fluoride with a physical film thickness of 300 nm is provided on the light-emitting side of the wavelength conversion member. Furthermore, the ceramic composite can be, for example, ceramic composite A described below. 5 shows an example of a wavelength conversion member including a light-transmitting thin film having a physical film thickness in the range of 250 nm to 330 nm. The physical film thickness of the light-transmitting thin film is not limited to 300 nm as shown in FIG. 5, and is not limited to the range of 250 nm to 330 nm. As mentioned above, when the wavelength conversion member does not include a light-transmitting thin film, at a directivity angle near 0 degrees (θ=0° in FIG. 4), light from the light-emitting element having an emission peak wavelength in the range of 380 nm to 500 nm tends to be more easily emitted. In a light-emitting device equipped with a wavelength conversion member including a translucent thin film, at a directivity angle of 0 degrees, the light emitted from the light-emitting element, which has an emission peak wavelength in the range of 380 nm to 500 nm and which is easily emitted, is mixed with the light emitted from the inorganic phosphor, which has an emission peak wavelength in the range of 510 nm to 570 nm and which is easily transmitted by the translucent thin film.Therefore, even in areas close to a directivity angle of 0 degrees, only the light emitted from the light-emitting element is strong, and no large change in chromaticity occurs.The balance between the light emitted from the light-emitting element and the light emitted from the inorganic phosphor is maintained, resulting in improved orientation chromaticity characteristics.

[0047] Next, a case where the angle of inclination from the light emitting surface of the light emitting device to the horizontal direction, that is, the directivity angle, changes from a directivity angle of 0 degrees (θ=0° in FIG. 4) parallel to the optical axis z will be described. At angles inclined from a directivity angle of 0 degrees, which is a direction parallel to the optical axis z, to a direction horizontal to the light-emitting surface of the light-emitting device, for example, at a directivity angle of +60 degrees and a directivity angle of -60 degrees (θ=+60° on the x-axis or y-axis, and -60° on the x-axis or y-axis in FIG. 4), the transmittance of the emission of the inorganic phosphor (e.g., emission with a peak emission wavelength of around 550 nm) is lower than that of the emission of the light-emitting element (e.g., emission with a peak emission wavelength of around 450 nm). That is, when the wavelength conversion member includes a translucent thin film, the emission of the inorganic phosphor contained in the wavelength conversion member is more difficult to transmit through the translucent thin film at a directivity angle of +60 degrees and a directivity angle of -60 degrees compared to when the wavelength conversion member does not include a translucent thin film. Furthermore, when the wavelength conversion member includes a translucent thin film, the emission of the inorganic phosphor tends to be more difficult to emit at a directivity angle of +60 degrees and a directivity angle of -60 degrees compared to when the wavelength conversion member does not include a translucent thin film. As shown in FIG. 5, when the directivity angle is plus 60 degrees or minus 60 degrees (+60° or −60°) and the wavelength conversion member is provided with a translucent thin film that satisfies specific conditions, the transmittance of the wavelength conversion member provided with the translucent thin film becomes lower at wavelengths exceeding 470 nm than when the directivity angle is 0 degrees (0°), and it becomes difficult for the light emitted by the inorganic phosphor to be emitted. As mentioned above, when the angle of inclination from the directivity angle of 0° to the horizontal direction increases, for example, when the directivity angle changes from 0° to plus 90° or minus 90° (in Figure 4, from θ=0° to θ=+90° on the x-axis or y-axis, and from θ=0° to −90° on the x-axis or y-axis), if the wavelength conversion member does not include a translucent thin film, the light emitted from the inorganic phosphor within the range of 510 nm or more and 570 nm or less tends to be more easily emitted. In a light emitting device equipped with a wavelength conversion member including a translucent thin film, when the directivity angle changes from 0 degrees to plus 90 degrees or minus 90 degrees, for example, when the directivity angle changes to plus 60 degrees or minus 60 degrees, the light from the light emitting element, which has an emission peak wavelength in the range of 380 nm to 500 nm, and the emission of the inorganic phosphor, which has an emission peak wavelength in the range of 510 nm to 570 nm and is made less transparent by the translucent thin film, are mixed together. Therefore, even when the directivity angle changes from 0 degrees to plus 60 degrees or minus 60 degrees, only the emission from the inorganic phosphor becomes stronger, and no large change in chromaticity occurs. The balance between the emission from the light emitting element and the emission from the inorganic phosphor is maintained, resulting in improved orientation chromaticity characteristics. In this way, it is thought that under certain conditions, the degree of color mixing between the emission of the inorganic phosphor and the emission of the light-emitting element is similar in the direction of a directivity angle of 0 degrees, a directivity angle of +60 degrees, or a directivity angle of -60 degrees, and that the change in chromaticity is small even when the directivity angle is changed.

[0048] A fourth embodiment of the light-emitting device includes a wavelength conversion member including a single-layer light-transmitting thin film made of fluoride or silicon dioxide, and the L value derived from formula (2), which is the ratio of the physical film thickness L1 of the light-transmitting thin film to the optical film thickness L0 derived from formula (1), is within the range of 2.5 to 3.5. The fourth embodiment of the light-emitting device may include a single-layer light-transmitting thin film made of fluoride or silicon dioxide and having a physical film thickness L1 of 250 nm to 330 nm. When the light-emitting device includes a light-transmitting thin film having an L value derived from formula (2) within the range of 2.5 to 3.5, the change in chromaticity is small even when the directivity angle changes, and the alignment chromaticity characteristics can be improved. In order to improve the alignment chromaticity characteristics, the light-transmitting thin film included in the light-emitting device preferably has an L value within the range of 2.5 to 3.5, more preferably within the range of 2.5 to 3.4, and even more preferably within the range of 2.5 to 3.2.

[0049] Fig. 6 is an enlarged schematic diagram of a portion of the wavelength conversion member of a light emitting device. The scales of Figs. 3 and 6 may not be the same. When the L value for 550 nm derived from formula (2) approaches 3.0, the second reflected wave Rw2 generated at the interface If2 between the light-transmitting thin film 32 and air A for light in the 380 nm to 500 nm range is out of phase with the first reflected wave Rw1 generated at the interface If1 between the ceramic composite 31 and the light-transmitting thin film 32. This results in more light being reflected within the wavelength conversion member 30 than when the L value of the light-transmitting thin film 32 approaches 1.0, resulting in less light being transmitted than when the light-transmitting thin film 32 is not provided. When a light-emitting device is provided with a light-transmitting thin film having an L value derived from the formula (2) in the range of 2.5 to 3.5, a portion of the light emitted from the light-emitting device is reduced by reflection, and therefore the emission of light in the range of 380 nm to 500 nm, which is easily emitted from the light-emitting device, is reduced at a directivity angle of 0 degrees. Also, when a light-emitting device is provided with a light-transmitting thin film having an L value derived from the formula (2) in the range of 2.5 to 3.5, and the directivity angle of light emitted from the light-emitting device approaches the directivity angle +90 degrees or the directivity angle -90 degrees, the emission of light in the range of 510 nm to 570 nm, which is easily emitted from the light-emitting device, is reduced. When a light-emitting device is provided with a translucent thin film having an L value in the range of 2.5 or more and 3.5 or less, the emission of light of 380 nm or more and 500 nm or less, which is likely to be emitted at a directivity angle of 0 degrees, is reduced, and the emission of light of 510 nm or more and 570 nm or less, which is likely to be emitted as the directivity angle approaches plus 90 degrees or minus 90 degrees, is reduced, thereby reducing color unevenness due to changes in the directivity angle and improving the orientation chromaticity characteristics.

[0050] A light emitting device of a fifth aspect preferably includes a wavelength conversion member including a light-transmitting thin film made of fluoride or silicon dioxide, and emits light that satisfies the following: a first transmittance difference T1 calculated based on the following formula (3) obtained by subtracting the difference in transmittance of light transmitted through the light emitting surface of the wavelength conversion member at a directivity angle of 0 degrees at the emission peak wavelength of the inorganic phosphor and the emission peak wavelength of the light emitting element from the difference in transmittance of light transmitted through the light emitting surface of the wavelength conversion member at a directivity angle of +60 degrees or -60 degrees at the emission peak wavelength of the inorganic phosphor and the emission peak wavelength of the light emitting element. The light emitting device may also emit light that satisfies the following: a second transmittance difference T2 calculated based on the following formula (4) is within the range of -3% to 10%. The light-transmitting thin film made of fluoride or silicon dioxide is preferably a single layer. T1=T C-60 -T P-60 -(T C-0 -T P-0 ) (3) (In formula (3), T C-60 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element with a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees. P-60 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees. C-0 is the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of a light emitting element with a directivity angle of 0 degrees. P-0 is the transmittance of light transmitted from the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of 0 degrees. A directivity angle of 0 degrees is the angle perpendicular to the light-emitting surface, and a directivity angle of +60 degrees and a directivity angle of -60 degrees are angles of +60 degrees and -60 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center.)

[0051] The transmittance of light transmitted through a wavelength conversion member refers to the ratio of the intensity I1 of light transmitted through the wavelength conversion member to the intensity I0 of light incident on the wavelength conversion member, and can be calculated by the following formula (10). Transmittance (%)=I1÷I0×100 (10) Here, I0 is the intensity of the light from the light emitting element that is incident on the wavelength conversion member, and I1 is the intensity of the transmitted light that has passed through the wavelength conversion member.

[0052] The intensity of transmitted light from the light-emitting surface of the wavelength conversion member varies depending on the wavelength and directivity angle of the transmitted light. If a light-emitting device can emit light such that a first transmittance difference T1 is within a range of 0% to 25%, which is calculated by subtracting the difference in transmittance of transmitted light from the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the light-emitting element and the emission peak wavelength of the inorganic phosphor from the difference in transmittance of transmitted light from the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the light-emitting element and the emission peak wavelength of the inorganic phosphor at a directivity angle of 0 degrees, the change in orientation chromaticity due to changes in the directivity angle will be small even if the directivity angle changes, and the orientation chromaticity characteristics of the light emitted from the light-emitting device can be improved.

[0053] As mentioned above, the light emitted by a light-emitting device tends to have a high transmittance of light at the emission peak wavelength of the light-emitting element at a directivity angle of 0 degrees, and the transmittance of light at the emission peak wavelength of the inorganic phosphor tends to increase as the directivity angle approaches plus 90 degrees or minus 90 degrees. If the light emitting device can emit light such that the value of the first transmittance difference T1 is within the range of 0% or more and 25% or less, the transmittance of light of the emission peak wavelength of the inorganic phosphor will be high at a directivity angle close to 0 degrees, maintaining a balance with the transmittance of light of the emission peak wavelength of the light emitting element, which tends to be high at a directivity angle close to 0 degrees, and improving the orientation chromaticity characteristics of the light emitted by the light emitting device.

[0054] The light emitted from the light emitting device may satisfy the first transmittance difference T1 being in the range of 3% to 22%, or may satisfy the range of 5% to 20%, preferably in the range of 8% to 15%, more preferably in the range of 10% to 14%, even more preferably in the range of 11% to 14%, and particularly preferably in the range of 12.5% ​​to 13.5%. If the light emitted from the light emitting device satisfies the first transmittance difference T1 being in the range of 8% to 15%, the difference Δx in orientation chromaticity is small, and in a graph showing the relationship between the directivity angle and the difference Δx in orientation chromaticity, even if the directivity angle increases, the curve becomes closer to a horizontal line, thereby improving the orientation chromaticity characteristics.

[0055] When the value of the first transmittance difference T1 of the light emitted by the light emitting device is less than 0% or exceeds 25%, the transmittance of light of the emission peak wavelength of the light emitting element increases at a directivity angle close to 0 degrees, and the transmittance of light of the emission peak wavelength of the light emitting element, which tends to increase at a directivity angle close to 0 degrees, further increases. The light emitted by the light emitting device when the first transmittance difference T1 is less than 0% or exceeds 25%, exhibits a large change in chromaticity and poor alignment chromaticity characteristics. Furthermore, the light emitted by the light emitting device when the value of ... of light of the emission peak wavelength of the inorganic phosphor, which tends to increase at a directivity angle close to +60 degrees or -60 degrees, and the transmittance of light of the emission peak wavelength of the inorganic phosphor, which tends to increase at a large directivity angle, further increases, resulting in a change in chromaticity and poor alignment chromaticity characteristics.

[0056] A light emitting device of a fifth aspect preferably includes a wavelength converting member including a light-transmitting thin film made of fluoride or silicon dioxide, and emits light satisfying the following: A second transmittance difference T2 calculated based on the following formula (4) obtained by subtracting the difference in transmittance of light transmitted through the light emitting surface of the wavelength converting member at a directivity angle of 0 degrees at the emission peak wavelength of the inorganic phosphor and the emission peak wavelength of the light emitting element from the difference in transmittance of light transmitted through the light emitting surface of the wavelength converting member at a directivity angle of +30 degrees or -30 degrees at the emission peak wavelength of the inorganic phosphor and the emission peak wavelength of the light emitting element is within the range of -3% to 10%. The light emitting device may also emit light satisfying the following: A first transmittance difference T1 calculated based on the formula (3) is within the range of 0% to 25%. The light-transmitting thin film made of fluoride or silicon dioxide is preferably a single layer. T2=T C-30 -T P-30 -(T C-0 -T P-0 ) (4) (In formula (4), T C-30 is the average value of the transmittance of light transmitted through the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the light-emitting element with a directivity angle of plus 30 degrees and a directivity angle of minus 30 degrees, and T P-30 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of plus 30 degrees and a directivity angle of minus 30 degrees. C-0 , T P-0 The directivity angle of 0 degrees is the same as that of the above formula (3), and the directivity angle of plus 30 degrees and the directivity angle of minus 30 degrees are angles of plus 30 degrees and minus 30 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center.)

[0057] As long as the second transmittance difference T2 of the light emitted by the light emitting device is within the range of -3% to 10%, the change in chromaticity due to the change in the directivity angle is small, and the orientation chromaticity characteristics can be improved. The second transmittance difference T2 of the light emitted by the light emitting device may be within the range of -2% to 8%, or within the range of -1.5% to 5%. The second transmittance difference T2 of the light emitted by the light emitting device preferably is within the range of -1.2% to 4.5%. If the second transmittance difference T2 of the light emitted by the light emitting device is within the range of -3% to 10%, the transmittance of light at the emission peak wavelength of the inorganic phosphor increases at a directivity angle close to 0 degrees, maintaining a balance with the transmittance of light at the emission peak wavelength of the light emitting element, which tends to increase at a directivity angle close to 0 degrees, and improving the orientation chromaticity characteristics of the light emitted by the light emitting device. Also, if the value of the second transmittance difference T2 of the light emitted by the light emitting device is within the range of -3% to 10%, the transmittance of light at the emission peak wavelength of the light emitting element increases at a directivity angle close to +30 degrees or -30 degrees, maintaining a balance with the transmittance of light at the emission peak wavelength of the inorganic phosphor, which tends to increase as the directivity angle increases, and improving the orientation chromaticity characteristics of the light emitted by the light emitting device.

[0058] When the light-transmitting thin film is a single layer, the refractive index r2 of the light-transmitting thin film is preferably in the range of 1.32 to 1.48, and may be in the range of 1.33 to 1.47. When the refractive index r2 of the light-transmitting thin film is in the range of 1.32 to 1.48, the first reflected wave generated at the interface between the ceramic composite and the light-transmitting thin film is canceled out by the second reflected wave, which is in the opposite phase, generated at the interface between the light-transmitting thin film and air, thereby reducing reflection at the wavelength conversion member and enabling light with a high luminous flux to be emitted from the light-emitting device.

[0059] When the translucent thin film is a single layer, the refractive index ratio (r1 / r2) of the refractive index r1 of the ceramic composite to the refractive index r2 of the translucent thin film is preferably within the range of 1.18 to 1.41, and may be within the range of 1.20 to 1.40, 1.25 to 1.35, or 1.28 to 1.32. When the refractive index ratio (r1 / r2) of the refractive index r1 of the ceramic composite to the refractive index r2 of the translucent thin film is within the range of 1.18 to 1.41, reflection at the interface between the ceramic composite and the translucent thin film is canceled out by reflection at the interface between the translucent thin film and air, reducing reflection at the wavelength conversion member and enabling light with a high luminous flux to be emitted from the light emitting device.

[0060] The light-transmitting thin film may not be a single layer, but may be a multilayer film including at least two layers, a first layer and a second layer. When the light-transmitting thin film is a multilayer film, for example, a commercially available optical multilayer film can be used. When the light-transmitting thin film is a multilayer film, it includes at least two layers: a first layer made of fluoride or silicon dioxide containing at least one element selected from the group consisting of alkali metals, alkaline earth metals, and Group 13 metal elements; and a second layer made of an oxide containing at least one element selected from the group consisting of aluminum, niobium, tantalum, titanium, and zirconium.When there are two or more layers, it is a multilayer film in which the first and second layers are alternately stacked.The refractive index of the first layer and the refractive index of the second layer are different from each other.The fluoride can be the same as that used in the single-layer light-transmitting thin film.

[0061] In a light emitting device of a sixth aspect, the light-transmitting thin film is a multilayer film including at least a first layer and a second layer, and the light emitting device preferably emits light that satisfies the following: a third transmittance difference T3 calculated based on the following formula (5) obtained by subtracting the difference in transmittance of transmitted light through the light emitting surface of the wavelength conversion member at a directivity angle of 0 degrees at the emission peak wavelength of the inorganic phosphor and the emission peak wavelength of the light emitting element from the difference in transmittance of transmitted light through the light emitting surface of the wavelength conversion member at a directivity angle of 0 degrees at the emission peak wavelength of the inorganic phosphor and the emission peak wavelength of the light emitting element is within a range of 0% to 20%. The light emitting device may also emit light that satisfies the following: a first transmittance difference T1 calculated based on the above formula (3) is within a range of 0% to 25%. T3=T C-45 -T P-45 -(T C-0 -T P-0 ) (5) (In formula (5), T C-45 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element at a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees, and T P-45 is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees. C-0 , T P-0 The directivity angle of 0 degrees is the same as that of the above formula (3), and the directivity angle of plus 45 degrees and the directivity angle of minus 45 degrees are angles of plus 45 degrees and minus 45 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center.)

[0062] When the light-transmitting thin film is a multilayer film including at least a first layer and a second layer, if the light-emitting device can emit light having a third transmittance T3 in the range of 0% to 20%, the transmittance of light at the emission peak wavelength of the inorganic phosphor increases at a directivity angle close to 0 degrees, maintaining a balance with the transmittance of light at the emission peak wavelength of the light-emitting element, which tends to increase at a directivity angle close to 0 degrees, and improving the orientation chromaticity characteristics. Also, even when the light-transmitting thin film is a multilayer film, if the light-emitting device can emit light having a third transmittance T3 in the range of 0% to 20%, the transmittance of light at the emission peak wavelength of the light-emitting element increases even when the directivity angle changes, maintaining a balance with the transmittance of light at the emission peak wavelength of the inorganic phosphor, which tends to increase as the directivity angle increases, and improving the orientation chromaticity characteristics. When the light-transmitting thin film is a multilayer film including at least a first layer and a second layer, the light-emitting device preferably emits light that satisfies the first transmittance T1 within the range of 0% to 25%.

[0063] Method for manufacturing a light-transmitting thin film When the light-transmitting thin film is a single layer, it can be produced by chemical vapor deposition or physical vapor deposition. Examples of physical vapor deposition include electron beam deposition, resistance heating vapor deposition, ion plating, and sputtering. The light-transmitting thin film is preferably formed by resistance heating vapor deposition of a raw material, fluoride or silicon dioxide, on the light-emitting surface of the ceramic composite in a vacuum atmosphere at a temperature between 25°C and 400°C. When the light-transmitting thin film is a multilayer film, the raw materials for the first layer and the second layer may be formed in this order on the light-emitting surface of the ceramic composite by electron beam (EB) heating deposition in a vacuum atmosphere at a temperature in the range of 25°C to 400°C.

[0064] Next, the members other than the light emitting element and the wavelength conversion member that constitute the light emitting device will be described.

[0065] substrate The substrate is preferably made of an insulating material that is difficult for light from the light-emitting element and external light to pass through. Examples of substrate materials include ceramics such as aluminum oxide and aluminum nitride, and resins such as phenolic resin, epoxy resin, polyimide resin, bismaleimide triazine resin (BT resin), and polyphthalamide (PPA) resin. Ceramics are preferred as substrate materials because of their high heat resistance.

[0066] adhesive layer An adhesive layer is interposed between the light emitting element and the wavelength conversion member to fix the light emitting element and the wavelength conversion member. The adhesive constituting the adhesive layer is preferably made of a material that can optically connect the light emitting element and the wavelength conversion member. The material constituting the adhesive layer is preferably at least one resin selected from the group consisting of epoxy resin, silicone resin, phenol resin, and polyimide resin.

[0067] semiconductor elements Examples of semiconductor elements that may be provided in a light-emitting device as needed include transistors for controlling light-emitting elements and protective elements for preventing damage to or performance degradation of light-emitting elements due to application of excessive voltage, such as Zener diodes and capacitors.

[0068] Covering material The covering member is preferably made of an insulating material. More specifically, examples of the insulating material include phenolic resin, epoxy resin, bismaleimide triazine resin (BT resin), polyphthalamide (PPA) resin, and silicone resin. The covering member may contain at least one additive selected from the group consisting of colorants, phosphors, and fillers, as needed.

[0069] Conductive material Bumps can be used as the conductive members, and the bump material can be Au or its alloy, and other conductive members can be eutectic solder (Au-Sn), Pb-Sn, lead-free solder, etc.

[0070] The luminous color of the light emitting device is expressed as the chromaticity coordinate of the CIE 1931 chromaticity diagram, where the x-coordinate x0 of the luminous color of the light emitting device at a directivity angle of 0 degrees is the average of the x-coordinates of the luminous color of the light emitting device at a directivity angle of +60 degrees and -60 degrees. 60 The absolute value of the difference Δx between the orientation chromaticity of the light-emitting color of the light-emitting device and the chromaticity of the light-emitting color of the light-emitting device (hereinafter also referred to as "difference Δx in orientation chromaticity") is 0.012 or less. If the absolute value of the difference Δx between the orientation chromaticity of the light-emitting color of the light-emitting device is 0.012 or less, even if the directivity angle changes, the change in the chromaticity of the light-emitting color of the light-emitting device is small, and the orientation chromaticity characteristics can be improved. The x-coordinate x0 of the light-emitting color of the light-emitting device at a directivity angle of 0 degrees and the x-coordinate x0 of the average value of the directivity angle +60 degrees and the directivity angle -60 degrees 60 The absolute value of the difference Δx is more preferably 0.011 or less, even more preferably 0.010 or less, and even more preferably 0.009 or less, and may be 0 or 0.001 or more.

[0071] The luminous color of the light emitting device is expressed as the chromaticity coordinates of the CIE 1931 chromaticity diagram, where the y-coordinate y0 of the luminous color of the light emitting device at a directivity angle of 0 degrees is the y-coordinate y0, which is the average of the y-coordinates of the luminous color of the light emitting device at a directivity angle of +60 degrees and -60 degrees. 60 The absolute value of the difference Δy between the orientation chromaticity of the light emitting device and the luminous color of the light emitting device (hereinafter also referred to as "orientation chromaticity difference Δy") is preferably 0.032 or less, and may be 0.031 or less, 0.030 or less, 0.029 or less, 0, or 0.001 or more. If the absolute value of the difference Δy between the orientation chromaticity of the light emitting device and the luminous color of the light emitting device is 0.032 or less, even if the directivity angle changes, the change in the chromaticity of the light emitting device is small, and the orientation chromaticity characteristics can be improved.

[0072] Light-emitting device manufacturing method An example of a method for manufacturing a light emitting device will be described. For details, refer to the disclosures of, for example, Japanese Patent Application Laid-Open No. 2014-112635 or Japanese Patent Application Laid-Open No. 2017-117912. The method for manufacturing a light emitting device preferably includes a step of arranging a light emitting element, a step of arranging a semiconductor element if necessary, a step of forming a wavelength conversion member including a ceramic composite, a step of bonding the light emitting element and the wavelength conversion member, and a step of forming a covering member.

[0073] Light-emitting element arrangement process In the step of arranging the light emitting element, the light emitting element is arranged on the substrate and mounted thereon, for example, by flip-chip mounting the light emitting element and the semiconductor element on the substrate.

[0074] Bonding process between light emitting element and wavelength conversion material In the step of bonding the light emitting element and the wavelength conversion member, the wavelength conversion member is placed opposite the light emitting surface of the light emitting element and bonded onto the light emitting element with an adhesive layer.

[0075] Covering member forming process In the step of forming the covering member, the side surfaces of the light-emitting element and the wavelength conversion member excluding the light-emitting surface are covered with a composition for covering member, and the covering member is formed on the side surfaces of the light-emitting element and the wavelength conversion member excluding the light-emitting surface. This covering member is for reflecting light emitted from the light-emitting element, and is formed so as to cover the side surfaces without covering the light-emitting surface of the wavelength conversion member and to embed the semiconductor element.

[0076] In this manner, the light emitting device shown in FIGS. 1 and 2 can be manufactured. [Example]

[0077] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0078] Manufacturing of ceramic composite A As inorganic phosphors, (Y 0.866 Gd 0.13 Ce 0.04 )3AlO 12A rare earth aluminate phosphor having the composition shown below was prepared. As the inorganic oxide, aluminum oxide (Al2O3) particles with a purity of 99 mass % were prepared. A raw material mixture was obtained by mixing 30 mass % of the rare earth aluminate phosphor and 70 mass % of aluminum oxide particles. The raw material mixture was filled into a mold and subjected to a pressure of 5 MPa (51 kgf / cm 2 A cylindrical compact with a diameter of 65 mm and a thickness of 15 mm was formed at a pressure of 176 MPa. The obtained compact was placed in a packaging container, vacuum-packed, and subjected to CIP at 176 MPa using a cold isostatic pressing device (manufactured by Kobe Steel, Ltd. (KOBELCO)) to obtain a compact. The obtained compact was subjected to primary firing in an air atmosphere (0.101 MPa, oxygen concentration 20% by volume) at a temperature of 1650°C using a firing furnace (manufactured by Marusho Denki Co., Ltd.) to obtain a first sintered body. The obtained first sintered body was subjected to secondary firing by HIP using a hot isostatic pressing (HIP) apparatus (manufactured by Kobe Steel, Ltd. (KOBELCO)) in a nitrogen gas atmosphere (99.99% by volume or more) using nitrogen gas as the pressure medium at a temperature of 1650°C and a pressure of 195 MPa for 2 hours to obtain a second sintered body. This second sintered body was cut into a predetermined shape and size using a wire saw, and the cut surface was polished with a surface grinder to obtain a plate-shaped ceramic composite A with a thickness of 180 μm. The refractive index r1 of ceramic composite A was 1.78. The refractive index r1 of ceramic composite A was determined by the refractive index of the rare earth aluminate phosphor in the ceramic composite, which was 1.82, the content was 30 mass%, and the true density was 4.77 g / cm. 3 and aluminum oxide, with a refractive index of 1.77, a content of 70 mass%, and a true density of 3.98 g / cm 3 Therefore, it can be calculated based on the above formula (6).

[0079] Fabrication of ceramic composite B As inorganic phosphors, (Y 0.828 Gd 0.17 Ce 0.002 )3AlO 12 A rare earth aluminate phosphor having the composition shown below was prepared. Ceramic composite B was obtained in the form of a plate with a thickness of 180 μm in the same manner as ceramic composite A, except that yttrium aluminum perovskite (YAlO3:YAP) particles were prepared as the inorganic oxide and a raw material mixture of 95 mass% of rare earth aluminate phosphor and 5 mass% of YAP particles was used. The refractive index r1 of ceramic composite B was 1.83. The refractive index r1 of ceramic composite B was obtained when the refractive index of the rare earth aluminate phosphor in the ceramic composite was 1.82, the content was 95 mass%, and the true density was 4.82 g / cm. 3 The refractive index of YAP is 1.93, the content is 5 mass%, and the true density is 5.55 g / cm 3 Therefore, it can be calculated based on the above formula (6).

[0080] Fabrication of ceramic composite C As inorganic phosphors, (Y 0.92 Gd 0.07 Ce 0.01 )3AlO 12 A rare earth aluminate phosphor having the composition shown below was prepared. A plate-shaped ceramic composite C having a thickness of 180 μm was obtained in the same manner as ceramic composite A, except that a raw material mixture containing 11.5 mass% of rare earth aluminate phosphor and 88.5 mass% of the aluminum oxide particles used in ceramic composite A was used. The refractive index r1 of ceramic composite C was 1.77. The refractive index r1 of ceramic composite C was calculated based on the refractive index of the rare earth aluminate phosphor in the ceramic composite, 1.82, the content of the rare earth aluminate phosphor in the ceramic composite, 11.5 mass%, and the true density of 4.69 g / cm. 3 The refractive index of aluminum oxide is 1.76, the content is 88.5 mass%, and the true density is 3.98 g / cm 3 Therefore, it can be calculated based on the above formula (6).

[0081] Light-emitting devices of Examples A-1 to A-3 Manufacturing of wavelength conversion materials Ceramic composite A and magnesium fluoride as a deposition material were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4Under a reduced pressure of 100 Pa, a microheater was used to form a transparent thin film (MgF2 film) with a physical film thickness of 102 nm, 111 nm, or 120 nm on the light-emitting surface of the ceramic composite A, which was the light-emitting side of the ceramic composite A, at a film-forming temperature of 300°C, by resistance heating deposition, to obtain wavelength conversion members A-1 to A-3 with each physical film thickness. The physical film thickness of the transparent thin film was measured using the method described below. The refractive index r2 of the transparent thin film was 1.38, which is the refractive index of MgF2. The refractive index ratio r1 / r2 between the refractive index r1 of the ceramic composite A and the refractive index r2 of the transparent thin film was 1.33.

[0082] Light-emitting device manufacturing 1 and 2 was fabricated using each of the obtained wavelength conversion members A-1 to A-3 as follows. A light emitting element 20 and a semiconductor element 70 were placed on a mounting substrate 10. Specifically, the light emitting element 20 was formed by laminating nitride semiconductors on a sapphire substrate, had a thickness of about 0.11 mm, a planar shape of a substantially square with sides of about 1.0 mm, and an emission peak wavelength of 450 nm. The light emitting element 20 and the semiconductor element 70 were arranged in a row so that the light emitting surface faced the sapphire substrate, which was a semiconductor growth substrate, and were flip-chip mounted on a conductive pattern formed on the mounting substrate 10 using a conductive member 60 made of Au. Next, silicone resin was placed on the upper surface of the light-emitting element 20 as adhesive 40, and the wavelength conversion member 30, which was formed into a plate-like shape from each ceramic composite of the examples and comparative examples, was bonded to the upper surface of the sapphire substrate of the light-emitting element 20. Next, the covering member 50 was placed along the side surfaces of the light emitting element 20 and the wavelength conversion member 30, and the semiconductor element 70 was completely buried in the covering member 50. Dimethyl silicone resin was used as the resin 51 contained in the covering member 50, and titanium oxide particles with an average particle size of 0.28 μm were contained as the light reflective material 52 in an amount of 60 mass % relative to the resin 51. Through these steps, the light emitting device 100 shown in FIGS. 1 and 2 was produced. The obtained light emitting device is the light emitting device of the first, second or seventh embodiment described above.

[0083] Light emitting device of comparative example a'-1 A light emitting device of Comparative Example a'-1 was fabricated in the same manner as in Example A-1, except that a ceramic composite A without a translucent thin film (physical film thickness of MgF2 film: 0 nm) was used.

[0084] Light emitting device of comparative example a'-2 A wavelength conversion member a'-2 was obtained by forming a light-transmitting thin film (MgF2 film) with a physical film thickness of 200 nm on the ceramic composite A in the same manner as in Example A-1. A light-emitting device of Comparative Example a'-2 was produced in the same manner as in Example A-1, except that the wavelength conversion member a'-2, in which the light-transmitting thin film (MgF2 film) had a physical film thickness of 200 nm, was used.

[0085] Light-emitting devices of Examples B-1 to B-5 Ceramic composite B and magnesium fluoride as a deposition material were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4 Under reduced pressure to 100 Pa, a microheater was used to form a translucent thin film (MgF2 film) with physical thicknesses of 85 nm, 88 nm, 103 nm, 113 nm, or 122 nm on the light-emitting surface of the ceramic composite B, which was the light-emitting side of the ceramic composite B. The temperature during film formation was 300°C. This formed the wavelength conversion members B-1 to B-5. The physical thickness of the translucent thin film was measured using the method described below. The light-emitting devices of Examples B-1 to B-5 were fabricated in the same manner as Example A-1, except for using these wavelength conversion members. The refractive index r2 of the translucent thin film was 1.38, which is the refractive index of MgF2. The refractive index ratio r1 / r2 between the refractive index r1 of the ceramic composite B and the refractive index r2 of the translucent thin film was 1.33.

[0086] Light emitting device of comparative example b'-1 A light emitting device of Comparative Example b'-1 was fabricated in the same manner as in Example B-1, except that a ceramic composite B without a light-transmitting thin film (physical film thickness of MgF2 film: 0 nm) was used.

[0087] Light emitting device of comparative example b'-2 A wavelength conversion member b'-2 was obtained by forming a translucent thin film (MgF2 film) with a physical film thickness of 205 nm on the ceramic composite B in the same manner as in Example B-1. A light-emitting device of Comparative Example b'-2 was produced in the same manner as in Example B-1, except that wavelength conversion member b'-2, in which the translucent thin film (MgF2 film) had a physical film thickness of 205 nm, was used.

[0088] Light-emitting devices of Examples C-1 to C-5 Ceramic composite C and magnesium fluoride were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4 Under reduced pressure to 100 Pa, ceramic composite C was formed on the light-emitting surface (the light-emitting side) of ceramic composite B by resistance heating deposition using a microheater. The temperature during film formation was 300°C. A translucent thin film (MgF2 film) with physical film thicknesses of 83 nm, 90 nm, 100 nm, 115 nm, or 123 nm was then formed on the ceramic composite C by resistance heating deposition, yielding wavelength conversion members C-1 to C-5 with each physical film thickness. The physical film thickness of the translucent thin film was measured using the method described below. Light-emitting devices of Examples C-1 to C-5 were fabricated in the same manner as Example A-1, except for using these wavelength conversion members. The refractive index r2 of the translucent thin film was 1.38, which is the refractive index of MgF2. The refractive index ratio r1 / r2 between the refractive index r1 of ceramic composite C and the refractive index r2 of the translucent thin film was 1.28.

[0089] Light emitting device of comparative example c'-1 A light emitting device of Comparative Example c'-1 was fabricated in the same manner as in Example C-1, except that a ceramic composite C without a light-transmitting thin film (physical film thickness of MgF2 film: 0 nm) was used.

[0090] Light emitting device of comparative example c'-2 A wavelength conversion member c'-2 was obtained by forming a translucent thin film (MgF2 film) with a physical film thickness of 148 nm on the ceramic composite C in the same manner as in Example C-1. A light emitting device of Comparative Example c'-2 was produced in the same manner as in Example C-1, except that wavelength conversion member c'-2, in which the translucent thin film (MgF2 film) had a physical film thickness of 148 nm, was used.

[0091] The light-transmitting thin films of the wavelength conversion members used in the Examples and Comparative Examples and the light-emitting devices of the Examples and Comparative Examples were evaluated as follows. A constant current of 350 mA was applied to each light-emitting device for measurement. The results are shown in Tables 1 to 3.

[0092] Physical thickness of the translucent thin film of the wavelength conversion material The physical thickness L1 of the light-transmitting thin film was measured from a cross-sectional SEM photograph of each wavelength conversion member. The physical thickness of the light-transmitting thin film was measured at three points on the cross-sectional SEM photograph of the wavelength conversion member, and the arithmetic average value was used as the physical thickness of the light-transmitting thin film.

[0093] L value The optical thickness L0 (nm) of the light-transmitting thin film was calculated from the following formula (1). The emission peak wavelength of the rare earth aluminate phosphor used in ceramic composites A to C was 550 nm, and the refractive index of the light-transmitting thin film was set to 1.38, when the light-transmitting thin film was an MgF2 film made of MgF2. Furthermore, the refractive index of SiO2 was set to 1.47, when the light-transmitting thin film was an SiO2 film made of SiO2. Furthermore, the L value was calculated from the physical thickness L1 and optical thickness L0 of each wavelength conversion member used in the examples and comparative examples based on the following formula (2). L0 = emission peak wavelength (λ) (nm) of inorganic phosphor ÷ (4 × refractive index of transparent thin film) (1) L=Physical thickness of transparent thin film L1 (nm) ÷ L0 (2)

[0094] Chromaticity coordinates (x, y) For each light-emitting device in the examples and comparative examples, the chromaticity coordinates (x, y) on the CIE 1931 chromaticity diagram were determined using an optical measurement system that combines a multichannel spectrometer and an integrating sphere. The chromaticity coordinates (x, y) of the emitted color of each light-emitting device refer to the chromaticity coordinates (x0, y0) at a directivity angle of 0 degrees.

[0095] Relative Luminous Flux For each of the light-emitting devices of the Examples and Comparative Examples, the total luminous flux was measured using a spectrophotometer (PMA-11, manufactured by Hamamatsu Photonics K.K.) with an integrating sphere. For the light-emitting devices of Examples A-1 to A-3 and Comparative Examples a'-1 and a'-2, the total luminous flux of the light emitted from the light-emitting device of Comparative Example a'-1, in which the physical thickness of the light-transmitting thin film is 0 nm, was set to 100%, and the total luminous flux of each light-emitting device was expressed as a relative value. For the light-emitting devices of Examples B-1 to B-5 and Comparative Examples b'-1 and b'-2, the total luminous flux of the light emitted from the light-emitting device of Comparative Example b'-1, in which the physical thickness of the light-transmitting thin film is 0 nm, was set to 100%, and the total luminous flux of each light-emitting device was expressed as a relative value. For the light emitting devices of Examples C-1 to C-5 and Comparative Examples c'-1 and c'-2, the total luminous flux of each light emitting device was expressed as a relative value (relative luminous flux (%)), with the total luminous flux of the light emitted from the light emitting device of Comparative Example c'-1, in which the physical film thickness of the light-transmitting thin film was 0 nm, being 100%.

[0096] Oriented chromaticity coordinate (x θ , y θ ) A diffuser plate with a light receiving area of ​​100 mm was placed on a rotating table 100 mm away in the optical axis direction (perpendicular direction) from the diffuser plate connected to a multi-spectrophotometer (PMA-11, manufactured by Hamamatsu Photonics K.K.). 2 The light emitting device was placed so that the light emitting surface faced a diffuser plate with a circular aperture, and a constant current of 350 mA was passed through the light emitting device to measure the chromaticity coordinates (x0, y0) of the emitted color at a directivity angle of 0 degrees parallel to the optical axis. Next, the turntable was rotated left and right so that it was 60 degrees from the optical axis, and the x-coordinate x of the average value of the directivity angle of +60 degrees and the directivity angle of -60 degrees was measured. 60 and the y-coordinate y of the average value of the directional angle of 60 degrees and the directional angle of -60 degrees 60 , the orientation chromaticity coordinate (x 60 , y 60 The orientation chromaticity coordinate (x 60 , y 60) refers to the average value of two values ​​obtained by moving the rotating table left and right at a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees. In the chromaticity coordinates of the CIE1931 chromaticity diagram, the x-coordinate x0 of the emitted color of the light-emitting device at a directivity angle of 0 degrees and the x-coordinate x0 which is the average value of the emitted color of the light-emitting device at a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees are used. 60 The absolute value of the difference Δx (the difference Δx in the orientation chromaticity) was measured. θ , y θ ) is the orientation chromaticity coordinate (x) of the average value of the directivity angle plus θ degrees and the directivity angle minus θ degrees. θ , y θ )

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] The light-emitting devices according to Examples A-1 to A-3, the light-emitting devices according to Examples B-1 to B-5, and the light-emitting devices according to Examples C-1 to C-5 have a single layer of translucent thin film with a physical thickness of 82 nm to 140 nm, and all of them have a higher relative luminous flux than the light-emitting device according to Comparative Example a'-1, the light-emitting device according to Comparative Example b'-1, and the light-emitting device according to Comparative Example c'-1.

[0101] The light-emitting devices according to Examples A-1 to A-3, the light-emitting devices according to Examples B-1 to B-5, and the light-emitting devices according to Examples C-1 to C-5 had L values ​​of the translucent thin film in the range of 0.82 to 1.41, and all of them had higher relative luminous flux than the light-emitting devices according to Comparative Examples a'-1, b'-1, and c'-1, which did not have a translucent thin film. In the light-emitting devices according to the examples, the second reflected wave generated at the interface between the translucent thin film and air and the first reflected wave generated at the interface between the ceramic composite and the translucent thin film approach a phase inverse to each other, and the effect of the first reflected wave and the second reflected wave canceling each other out is enhanced, which is thought to reduce reflection within the wavelength conversion member and enable light with a higher luminous flux to be emitted from the light-emitting device.

[0102] In the light-emitting devices according to Examples A-1 to A-3, the absolute value of the difference Δx in orientation chromaticity was 0.012 or less, and even when the directional angle changed, the change in chromaticity of the emitted color of the light-emitting device was small, thereby improving the orientation chromaticity characteristics.

[0103] The light emitting device according to Comparative Example a'-2, the light emitting device according to Comparative Example b'-2, and the light emitting device according to Comparative Example c'-2 all had a physical film thickness of the translucent thin film exceeding 140 nm and an L value exceeding 1.41. In the light emitting device according to Comparative Example a'-2, the light emitting device according to Comparative Example b'-2, and the light emitting device according to Comparative Example c'-2, the second reflected wave generated at the interface between the translucent thin film and air was out of phase with the first reflected wave generated at the interface between the ceramic composite and the translucent thin film, reducing the effect of the first reflected wave and the second reflected wave canceling each other out, and light was reflected within the wavelength conversion member, resulting in a lower relative luminous flux than the light emitting device according to Comparative Example a'-1, the light emitting device according to Comparative Example b'-1, and the light emitting device according to Comparative Example c'-1, which did not have a translucent thin film.

[0104] FIG. 7 is a diagram showing the relationship between the physical film thickness of the translucent thin film and the relative luminous flux of each light-emitting device according to Examples A-1 to A-3, Comparative Examples a'-1 to a'-2, Examples B-1 to B-5, Comparative Examples b'-1 to b'-2, Examples C-1 to C-5, and Comparative Examples c'-1 to c'-2. As shown in FIG. 7, it can be seen that when the physical thickness of the light-transmitting thin film is within the range of 82 nm to 140 nm, light with a high relative luminous flux is emitted from the light-emitting device.

[0105] Light-emitting device of Example A-4 Ceramic composite A and magnesium fluoride were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4 Under a reduced pressure of 100 Pa, a light-transmitting thin film (MgF2 film) having a physical film thickness of 299 nm was formed by resistance heating deposition on the light-emitting surface of the ceramic composite A, which was the light-emitting side of the ceramic composite A, using a microheater to a film-forming temperature of 300°C, to obtain wavelength conversion members A-4 having the respective physical film thicknesses. The light-emitting device of Example A-4 was produced in the same manner as Example A-1, except that these wavelength conversion members were used. The obtained light-emitting device is a light-emitting device of any one of the third to seventh embodiments described above.

[0106] Light-emitting device of Example B-6 Ceramic composite B and magnesium fluoride were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4 Under a reduced pressure of 100 Pa, a light-transmitting thin film (MgF2 film) having a physical film thickness of 304 nm was formed by resistance heating deposition on the light-emitting surface of the ceramic composite B, which was the light-emitting side of the ceramic composite B, with the temperature during film formation set to 300°C, using a microheater, to obtain wavelength conversion members B-6 having the respective physical film thicknesses. The light-emitting device of Example B-6 was produced in the same manner as in Example B-1, except that these wavelength conversion members were used.

[0107] Light-emitting devices of Examples C-6 to C-11 Ceramic composite C and magnesium fluoride were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4Under a reduced pressure of 100 Pa, a microheater was used to form a light-transmitting thin film (MgF2 film) with a physical film thickness of 254 nm, 284 nm, 293 nm, 303 nm, 314 nm, or 325 nm on the light-emitting surface, which is the light-emitting side of the ceramic composite C, by resistance heating deposition, with the temperature during film formation at 300°C, to obtain wavelength conversion members C-6 to C-11 with each physical film thickness. Light-emitting devices of Examples C-6 to C-11 were produced in the same manner as in Example C-1, except that these wavelength conversion members were used.

[0108] Light-emitting devices of comparative examples c'-3 and c'-4 Ceramic composite C and magnesium fluoride were placed in the deposition device, and the pressure in the deposition device was increased to 1.0 × 10 -4 Under a reduced pressure of 100 Pa, a microheater was used to form a light-transmitting thin film (MgF2 film) with a physical film thickness of 203 nm or 353 nm on the light-emitting surface, which is the light-emitting side of the ceramic composite C, by resistance heating deposition at a film-forming temperature of 300°C, to obtain wavelength conversion members c'-3 and c'-4 with the respective physical film thicknesses. Light-emitting devices of Comparative Examples c'-3 and c'-4 were produced in the same manner as in Example C-1, except that these wavelength conversion members were used.

[0109] Light-emitting devices of Examples D-1 to D-4 Fabrication of ceramic composite D As inorganic phosphors, (Y 0.92 Gd 0.07 Ce 0.01 )3AlO 12 A rare earth aluminate phosphor having the composition shown below was prepared. A plate-shaped ceramic composite D having a thickness of 180 μm was obtained in the same manner as ceramic composite A, except that a raw material mixture containing 10 mass% of rare earth aluminate phosphor and 90 mass% of the aluminum oxide particles used in ceramic composite A was used. The refractive index r1 of ceramic composite D was 1.76. The refractive index r1 of ceramic composite D was calculated based on the refractive index of the rare earth aluminate phosphor in the ceramic composite, 1.82, the content of 10 mass%, and the true density of 4.69 g / cm. 3and aluminum oxide, with a refractive index of 1.76, a content of 90 mass%, and a true density of 3.98 g / cm 3 Therefore, it can be calculated based on the above formula (6).

[0110] Manufacturing of wavelength conversion materials Ceramic composite D and silicon dioxide were placed in a vapor deposition device, and the pressure in the vapor deposition device was increased to 1.0 × 10 -4 Under reduced pressure to 100 Pa, a microheater was used to form a transparent thin film (SiO2 film) with physical film thicknesses of 251 nm, 279 nm, 297 nm, and 319 nm on the light-emitting surface of ceramic composite D, which is the light-emitting side of ceramic composite D, by resistance heating deposition at a temperature of 300°C during film formation, to obtain wavelength conversion members D-1 to D-4 with each physical film thickness. The refractive index r2 of the transparent thin film is the refractive index of SiO2, 1.47. The refractive index ratio r1 / r2 between the refractive index r1 of ceramic composite D and the refractive index r2 of the transparent thin film was 1.19.

[0111] Light-emitting device manufacturing Light emitting devices of Examples D-1 to D-4 were produced in the same manner as in Example A-1, except that the obtained wavelength conversion members D-1 to D-4 were used.

[0112] Light-emitting device of comparative example d'-1 A light emitting device of Comparative Example d'-1 was fabricated in the same manner as in Example D-1, except that a ceramic composite D (SiO2 film physical thickness: 0 nm) without a translucent thin film was used.

[0113] Light-emitting devices of comparative examples d'-2 to d'-4 Wavelength conversion members d'-2, d'-3, and d'-4 were obtained by forming light-transmitting thin films (SiO films) with physical film thicknesses of 195 nm, 237 nm, and 347 nm on the ceramic composite D in the same manner as in Example D-1. Light-emitting devices of Comparative Examples d'-2 to d'-4 were fabricated in the same manner as in Example D-1, except that these wavelength conversion members d'-2, d'-3, and d'-4 were used.

[0114] In the same manner as described above, the physical film thickness, L value, chromaticity coordinates (x, y), relative luminous flux, and absolute value of the difference Δx in orientation chromaticity of the translucent thin film of the wavelength conversion member of each light-emitting device of the example and comparative example were measured. The results are shown in Tables 4 and 5. The chromaticity coordinates (x, y) of the emitted color of each light-emitting device refer to the chromaticity coordinates (x0, y0) at a directivity angle of 0 degrees.

[0115] [Table 4]

[0116] [Table 5]

[0117] In each of the light-emitting devices according to Example A-4, Example B-6, Examples C-6 to C-11, and Examples D-1 to D-4, the physical thickness of the translucent thin film was a single layer of 250 nm to 330 nm, and the light emitted by each light-emitting device had an absolute value of the difference in orientation chromaticity Δx of 0.012 or less, the difference in orientation chromaticity Δx due to changes in directional angle was small, the change in chromaticity due to directional angle was reduced, and the orientation chromaticity characteristics were good.

[0118] In each of the light-emitting devices according to Example A-4, Example B-6, Examples C-6 to C-11, and Examples D-1 to D-4, the L value of the translucent thin film was within the range of 2.5 or more and 3.5 or less, and the absolute value of the difference in orientation chromaticity Δx for the light emitted by each light-emitting device was 0.012 or less, the difference in orientation chromaticity Δx due to changes in directional angle was small, the change in chromaticity due to directional angle was reduced, and the orientation chromaticity characteristics were good.

[0119] In the light-emitting devices according to Comparative Example c'-3 and Comparative Examples d'-1 to d'-3, the physical thickness of the light-transmitting thin film was less than 250 nm, and the L value was less than 2.5. In the light-emitting devices according to Comparative Examples c'-4 and d'-4, the physical thickness of the light-transmitting thin film exceeded 340 nm, and the L value exceeded 3.5. The absolute value of the difference Δx in alignment chromaticity for the light emitted by the light-emitting devices according to Comparative Examples c'-3 to c'-4 and Comparative Examples d'-1 to d'-4 exceeded 0.012, which meant that the difference Δx in alignment chromaticity of the emitted light color due to changes in directivity angle was large, resulting in changes in chromaticity due to changes in directivity angle, and poor alignment chromaticity characteristics.

[0120] Fig. 8 is a graph showing the relationship between the directivity angle and the difference Δx in the orientation chromaticity coordinates of the light emitted by the light-emitting device according to Example A-4, in which the physical thickness of the translucent thin film is 299 nm, and the light emitted by the light-emitting device according to Comparative Example a'-1, in which the physical thickness of the translucent thin film is 0 nm. Fig. 9 is a graph showing the relationship between the directivity angle and the difference Δx in the orientation chromaticity coordinates of the light emitted by the light-emitting device according to Example B-6, in which the physical thickness of the translucent thin film is 304 nm, and the light-emitting device according to Comparative Example b'-1, in which the physical thickness of the translucent thin film is 0 nm. Fig. 10 is a graph showing the relationship between the directivity angle and the difference Δx in the orientation chromaticity coordinates of the light emitted by the light-emitting device according to Example C-8, in which the physical thickness of the translucent thin film is 293 nm, and the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the translucent thin film is 0 nm. 11 is a graph showing the relationship between the directional angle and the difference Δx in the orientation chromaticity of the light emitted by the light-emitting device according to Example D-2, in which the physical thickness of the translucent thin film is 279 nm, and the light-emitting device according to Comparative Example d'-1, in which the physical thickness of the translucent thin film is 0 nm. As shown in Figures 8 to 11, the light emitted by the light-emitting devices according to the examples exhibits a small change in the difference Δx in the orientation chromaticity of the emitted color due to the change in the directional angle, even when the directional angle is changed from 0 degrees to +60 degrees or -60 degrees. In the graph showing the relationship between the directional angle and the difference Δx in the orientation chromaticity, the curve becomes closer to a horizontal line even when the directional angle is increased, and the orientation chromaticity characteristics are improved.

[0121] Transmittance The light-emitting device according to Example C-6, in which the physical thickness of the light-transmitting thin film is 254 nm, the light-emitting device according to Example C-7, in which the physical thickness of the light-transmitting thin film is 284 nm, the light-emitting device according to Example C-9, in which the physical thickness of the light-transmitting thin film is 303 nm, the light-emitting device according to Example C-11, in which the physical thickness of the light-transmitting thin film is 325 nm, and the light-emitting device according to Comparative Example c'-4, in which the physical thickness of the light-transmitting thin film is 353 nm, were used to calculate the transmittance T C-0 , T C-30 , T C-45 , T C-60 and the transmittance T at the emission peak wavelength (550 nm) of the rare earth aluminate phosphor. P-0 , T P-30 , T P-45 , T P-60 Furthermore, the first transmittance difference T1, the second transmittance difference T2, and the third transmittance difference T3 were calculated from the following formulas (3) to (5). For each light emitting device of the example and comparative example, the x-coordinate x0 of the directivity angle of 0 degrees and the x-coordinate x 60 The results are shown in Table 6, along with the difference Δx. T1=T C-60 -T P-60 -(T C-0 -T P-0 ) (3) T2=T C-30 -T P-30 -(T C-0 -T P-0 ) (4) T3=T C-45 -T P-45 -(T C-0 -T P-0 ) (5) T C-60 : Average value of transmittance at the emission peak wavelength of 450 nm for light-emitting elements with a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees. T P-60: Average value of transmittance at emission peak wavelength of 550 nm of rare earth aluminate phosphor at directivity angle of plus 60 degrees and directivity angle of minus 60 degrees. T C-30 : Average value of transmittance at the emission peak wavelength of 450 nm for light-emitting elements with a directivity angle of plus 30 degrees and a directivity angle of minus 30 degrees. T P-30 : Average value of transmittance at emission peak wavelength of 550 nm of rare earth aluminate phosphor at directivity angle of plus 30 degrees and directivity angle of minus 30 degrees. T C-45 : Average value of transmittance at an emission peak wavelength of 450 nm for light-emitting elements with a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees. T P-45 : Average value of transmittance at emission peak wavelength of 550 nm of rare earth aluminate phosphor at directivity angle of plus 45 degrees and at directivity angle of minus 45 degrees. T C-0 : Transmittance of a light-emitting element with a directivity angle of 0 degrees at an emission peak wavelength of 450 nm. T P-0 : Transmittance of rare earth aluminate phosphor with a directivity angle of 0 degrees at an emission peak wavelength of 550 nm.

[0122] [Table 6]

[0123] The light emitting devices according to Examples C-6, C-7, C-9, and C-11 emitted light satisfying the following conditions: first transmittance difference T1 was in the range of 0% to 25%, second transmittance difference T2 was in the range of -3% to 10%, and third transmittance difference T3 was in the range of 0% to 20%. The light emitted by the light emitting devices according to Examples C-6, C-7, C-9, and C-11 had an absolute value of the difference Δx in alignment chromaticity of 0.012 or less, a small difference Δx in alignment chromaticity, small change in chromaticity due to directivity angle, and good alignment chromaticity characteristics.

[0124] The light emitting device according to Comparative Example c'-4 emitted light in which the first transmittance difference T1 was less than 0%, the second transmittance difference T2 was less than -3%, and the third transmittance difference T3 was less than 0%. The light emitted by the light emitting device according to Comparative Example c'-4 had poor alignment chromaticity characteristics, with the absolute value of the alignment chromaticity difference Δx exceeding 0.012.

[0125] Fig. 12 is a graph showing the relationship between the difference Δx in directional chromaticity and the light emission of a light-emitting device according to Example C-6, in which the physical thickness of the translucent thin film is 254 nm, and that of a light-emitting device according to Comparative Example c'-1, in which the physical thickness of the translucent thin film is 0 nm. Fig. 13 is a graph showing the relationship between the difference Δx in directional chromaticity and the light emission of a light-emitting device according to Example C-7, in which the physical thickness of the translucent thin film is 284 nm, and that of a light-emitting device according to Comparative Example c'-1, in which the physical thickness of the translucent thin film is 0 nm. Fig. 14 is a graph showing the relationship between the difference Δx in directional chromaticity and the light emission of a light-emitting device according to Example C-9, in which the physical thickness of the translucent thin film is 303 nm, and that of a light-emitting device according to Comparative Example c'-1, in which the physical thickness of the translucent thin film is 0 nm. Fig. 15 is a graph showing the relationship between the difference Δx in orientation chromaticity and the light-emitting device according to Example C-11, in which the physical thickness of the translucent thin film is 325 nm, and the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the translucent thin film is 0 nm. Fig. 16 is a graph showing the relationship between the difference Δx in orientation chromaticity and the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the translucent thin film is 0 nm, and the light-emitting device according to Comparative Example c'-4, in which the physical thickness of the translucent thin film is 353 nm.

[0126] 12 to 15, the emission of the light emitting devices according to the examples showed a small change in the difference Δx in alignment chromaticity even when the directivity angle was changed from 0 degrees to plus 60 degrees or minus 60 degrees. As shown in Fig. 13 to 15, the emission of the light emitting device according to Example C-7, Example C-9, and Example C-11, which had a first transmittance difference of 8% or more and 15% or less, showed a small difference Δx in alignment chromaticity, and in the graph showing the relationship between the directivity angle and the difference Δx in alignment chromaticity, the curve showed a shape closer to a horizontal line even when the directivity angle increased, and the alignment chromaticity characteristics were improved.

[0127] As shown in Figure 16, when the directional angle of the light-emitting device according to the comparative example changed from 0 degrees to plus 60 degrees or minus 60 degrees, the change in the difference Δx in orientation chromaticity increased, and the orientation chromaticity characteristics were poor. [Industrial Applicability]

[0128] The light emitting device according to the present disclosure can be used as an in-vehicle light source, a lighting device for general lighting, a backlight for a liquid crystal display device, or a light source for a projector. [Explanation of symbols]

[0129] 10: substrate, 20: light-emitting element, 30: wavelength conversion member, 31: ceramic composite, 32: light-transmitting thin film, 40: adhesive layer, 50: covering member, 60: conductive member, 70: semiconductor element, 100: light-emitting device, A: air.

Claims

1. a light-emitting element having an emission peak wavelength in the range of 380 nm to 500 nm; a wavelength conversion member having a light emitting surface and disposed on a light emitting side of the light emitting element, the wavelength conversion member is a ceramic composite including an inorganic phosphor and an inorganic oxide; a light-transmitting thin film disposed on the light exit side of the ceramic composite, the light-transmitting thin film comprises at least two layers, namely, a first layer made of silicon dioxide or fluoride containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and metal elements of Group 13, and a second layer made of an oxide containing at least one element selected from the group consisting of aluminum, niobium, tantalum, titanium, and zirconium, and when the light-transmitting thin film comprises two or more layers, the first layers and the second layers are alternately laminated; A light emitting device that emits light satisfying the condition that a third transmittance difference T3 calculated based on the following formula (5) is in the range of 0% to 20%. T3=T Ｃ－４５ -T Ｐ－４５ -(T Ｃ－０ -T Ｐ－０ ) (5) (In the above formula (5), T Ｃ－４５ is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element at a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees, and T Ｐ－４５ is the average value of the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at directivity angles of plus 45 degrees and minus 45 degrees. Ｃ－０ is the transmittance of light transmitted through the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element with a directivity angle of 0 degrees, and T Ｐ－０ is the transmittance of light transmitted from the light-emitting surface of the wavelength conversion member at the emission peak wavelength of the inorganic phosphor at a directivity angle of 0 degrees. Here, the directivity angle of 0 degrees is the angle perpendicular to the light-emitting surface, and the directivity angle of +45 degrees and the directivity angle of -45 degrees are angles of +45 degrees and -45 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface, with the directivity angle of 0 degrees as the center.)

2. The fluoride is MgF ２ , CaF ２ , SrF ２ , AlF ３ , Na ３ AlF ６ , Na ５ Al ３ F １４ 2. The light-emitting device according to claim 1, comprising at least one selected from the group consisting of NaF and LiF.

3. 3. The light emitting device according to claim 1, wherein the inorganic phosphor comprises at least one phosphor selected from the group consisting of rare earth aluminate phosphors, silicate phosphors, and β-sialon phosphors.

4. 4. The light emitting device according to claim 3, wherein the rare earth aluminate phosphor has a composition represented by the following formula (I), the silicate phosphor has a composition represented by the following formula (II), and the β-sialon phosphor has a composition represented by the following formula (III): (Ln) １ １－ａ Yes ａ ) ３ (Al) ｃ Ga ｂ ) ５ O １２ (I) (In the formula (I), Ln １ is at least one first rare earth element selected from the group consisting of Y, Gd, Lu, and Tb, and a, b, and c are numbers that satisfy the following conditions: 0<a≦0.22, 0≦b≦0.4, 0<c≦1.1, 0.9≦b+c≦1.

1. Ca ｄ Eu ｅ Mẽ ｆ Yes ４ O ｇ Cl ｈ (II) (In formula (II), d, e, f, g, and h are numbers that satisfy the following relationships: 7.0≦d≦7.94, 0.01≦e≦1.0, 7.70≦d+e≦7.95, 0.9≦f≦1.1, 15.6≦g≦16.1, and 1.90<h≦2.00, respectively.) Yes ６－ｚ Al ｚ O ｚ N ８－ｚ :Eu (0<z≦4.2) (III)

5. The inorganic oxide contains at least Al and at least one rare earth element selected from the group consisting of Y, Gd, Tb, and Lu. ２ 5. The light emitting device according to claim 1, further comprising an oxide which may contain:

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