Light emitting device

Abstract

To provide a light emitting device that emits light having a high light flux.SOLUTION: There is provided a light emitting device 100 including: a light emitting element 20 which has a light emission peak wavelength in a range of 380 nm or more and 500 nm or less; and a wavelength converting member 30 which is disposed on a light emission side of the light emitting element 20 and has a light emitting plane. The wavelength converting member 30 includes: a ceramic composite 31 which includes an inorganic fluorescent material having a light emission peak wavelength in a range of 510 nm or more and 570 nm or less and an inorganic oxide; and a translucent thin film 32 which is disposed on a light emission side of the ceramic composite 31 and has a refractive index smaller than the refractive index of the ceramic composite 31. The translucent thin film 32 is a single layer having a physical film thickness in a range of 82 nm or more and 140 nm or less. The translucent thin film 32 comprises a fluoride containing at least one kind of an element selected from a 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] There is known a light emitting device that includes 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 light emitting element such as the LED or LD. Such a light emitting device is used as a light source for, for example, in-vehicle lighting, general lighting, backlighting of liquid crystal display devices, projectors, etc.

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

[0004] [Patent Document 1] JP 2014-186882 A Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for light emitting devices using a ceramic composite containing an inorganic phosphor and an inorganic oxide that emit light with a 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 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 and an inorganic oxide, and a light-transmitting 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 light-transmitting thin film is a single layer 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, and an L value derived from the following formula (2), which is a ratio of a physical thickness L1 of the light-transmitting thin film to an optical thickness L0 of the light-transmitting thin film derived from the following formula (1), 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 fluoride or silicon dioxide 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 or more and 500 nm or less, 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 light-transmitting 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-transmitting 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 L value derived from the 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 the formula (1) of the light-transmitting 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 or more and 500 nm or less, 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 or more and 570 nm or less 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 metal elements of Group 13, and the light emitting device emits light satisfying at least one of the following: a first transmittance difference T1 calculated based on the following formula (3) is in the range of 0% or more and 25% or less, and a second transmittance difference T2 calculated based on the following formula (4) is in the range of -3% or more and 10% or less. 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 having 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 having 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 with 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 plus 60 degrees and the directivity angle of minus 60 degrees are angles of plus 60 degrees and minus 60 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface with a directivity angle of 0 degrees as the center, 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 a 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 or more and 500 nm or less, and a wavelength conversion member having a light emitting surface and disposed on the light emission side of the light emitting element, the wavelength conversion member including 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 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, the light transmissive thin film being an alkali metal The light emitting device 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 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 laminated, and emits light satisfying the following: 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 having 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 with 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 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.)

[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 conversion member having a light emitting surface and disposed on the light emission side of the light emitting element, the wavelength conversion member including 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, the light transmissive thin film being 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 metal elements of Group 13, and an x ​​coordinate x0 of the emission color of the light emitting device at a directivity angle of 0 degrees in chromaticity coordinates in the CIE 1931 chromaticity diagram being an average x coordinate of the emission color of the light emitting device at directivity angles of plus 60 degrees and minus 60 degrees, which are angles of plus 60 degrees and minus 60 degrees from a perpendicular angle to the light emitting surface toward the light emitting surface, 60 The absolute value of the difference Δx between the light emitting element and the light emitting element is 0.012 or less. Effect of the Invention

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

[0014] [Figure 1] FIG. 1 is a schematic plan view of a light emitting device. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the light emitting device. [Diagram 3] FIG. 3 is an image diagram showing a schematic enlarged 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. [Diagram 5] FIG. 5 is a diagram showing the relationship between the transmittance and the wavelength of light passing through a light-transmitting thin film for a light-emitting device having a light-transmitting thin film, with 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 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 of 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 of 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 of 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 of 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 of 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 of 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 of 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 of 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 PREFERRED EMBODIMENTS

[0015] The light emitting device will be described below based on the embodiments. However, the embodiments shown below are merely examples for embodying the technical idea of ​​the present invention, and the present invention is not limited to the light emitting device described below. The relationship between the color name and the chromaticity coordinates, and the relationship between the wavelength range of light and the color name of monochromatic light are in accordance with 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 conversion member having a light emitting surface and disposed on the light emission side of the light emitting element, the wavelength conversion member including a ceramic composite containing an inorganic phosphor 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. An example of the light emitting device will be described below.

[0017] FIG. 1 shows an example of a light emitting device, and 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 shown in FIG. 1 along line II-II'. The light emitting device 100 includes a light emitting element 20 made of an LED or LD, a ceramic composite 31 that is excited by light from the light emitting element 20 to emit light, and a wavelength conversion member 30 including a translucent thin film 32 arranged on the light emission side of the ceramic composite 31. The light emitting element 20 is flip-chip mounted on the substrate 10 via a bump that is a conductive member 60. The wavelength conversion member 30 includes the ceramic composite 31 provided 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 is incident from the light emitting element 20 side, and the translucent thin film 32 side serves as a light emission surface 31b. The translucent thin film 32 is arranged on the emission side of the ceramic composite 31. The light emitting element 20 and the wavelength conversion member 30 are covered with a covering member 50 that reflects light on their side. The light emitting element 20 can receive power from the outside of the light emitting device 100 through the wiring and conductive member 60 formed on the substrate 10 to cause 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 destruction due to application of an excessive voltage. The covering member 50 is provided so as to cover the semiconductor element 70, for example. The covering member 50 may include a resin 51 and at least one additive material 52 selected from the group consisting of a colorant, a phosphor, and a filler. Each member used in the light emitting device will be described below. For details, the disclosure of JP 2014-112635 A may be referred to.

[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 in the range of 380 nm or more and 500 nm or less, more preferably in the range of 390 nm or more and 495 nm or less, still more preferably in the range of 400 nm or more and 490 nm or less, and particularly preferably in 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 Ceramics composite The ceramics composite includes an inorganic phosphor and an inorganic oxide. The inorganic phosphor emits fluorescence having an emission peak wavelength in 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 in the range of 380 nm or more and 500 nm or less.

[0021] Inorganic phosphor The inorganic phosphor may be any one that emits fluorescence having an emission peak wavelength in 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 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 in the range of 99:1 to 80:20, or may be in 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 satisfying 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 that are the raw materials for forming the ceramic composite include aluminum oxide (Al2O3), yttrium oxide (Y2O3), 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 2 and the second rare earth element Ln 2 The composite oxide may include, for example, 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 amount of the ceramic composite. The content of the inorganic phosphor contained in the ceramic composite may be any amount that can provide light having a desired emission peak wavelength.

[0028] The thickness of the ceramic composite may be in the range of 50 μm to 500 μm, 60 μm to 450 μm, or 70 μm to 400 μm. The size of the ceramic composite used as the wavelength conversion member may be any size that covers 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, a translucent thin film having a refractive index smaller than that of the ceramic composite is disposed on the light output side, thereby reducing reflection at the wavelength conversion member and increasing 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 the 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 manufactured by forming a raw material mixture containing an inorganic phosphor and an inorganic oxide by a press molding method such as mold pressing and / or cold isostatic pressing (CIP), first firing the obtained molded body to obtain a sintered body, and then secondary firing the sintered body as necessary, such as hot isostatic pressing (HIP). Annealing treatment may be performed after secondary firing. The temperature at which the molded body is primarily fired may be in the range of 1550°C to 2000°C. The temperature at which the sintered body is secondary fired may be in the range of 1500°C to 2000°C. The temperature of the annealing treatment is lower than the firing temperatures of the primary firing and secondary firing, and may be in the range of 1000°C to 1500°C. For details of the method for manufacturing the ceramic composite, 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-layered light-transmitting thin film having a physical thickness L1 in the range of 82 nm to 140 nm. When the wavelength conversion member includes a single-layered light-transmitting thin film having a physical thickness L1 in the range of 82 nm to 140 nm on the light emission side of the ceramic composite, the reflection of light at the interface between the ceramic composite and the light-transmitting thin film is canceled by the reflection of light at the interface between the light-transmitting thin film and air, and the reflection at each interface is reduced, so that light with a high luminous flux is emitted from the light emitting device. The physical thickness L1 of the light-transmitting 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 include a light-transmitting thin film having an L value in the range of 0.82 to 1.41, as described later.

[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 light-transmitting thin film contains at least one selected from the group consisting of NaF and LiF. The light-transmitting 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 an image diagram showing an enlarged schematic view of a part 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 is first reflected at a first interface If1 between the ceramic composite 31 and the light-transmitting thin film 32, and becomes a first reflected wave Rw1 of a sine wave having a first period. The light emitted from the light emitting device is second reflected at a second interface If2 between the light-transmitting thin film 32 and air A, and becomes a second reflected wave Rw2 of a sine wave having a second period. Since 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] The light emitting device of the second embodiment includes a wavelength conversion member including a single-layer light-transmitting thin film made of a fluoride, and the L value derived from the following formula (2), which is the ratio of the physical thickness L1 of the light-transmitting thin film to the optical thickness L0 derived from the following formula (1) of the light-transmitting thin film, is in the range of 0.82 to 1.41. The light emitting device of the second embodiment may include a light-transmitting thin film that is a single layer made of a fluoride and has a physical thickness L1 of 82 nm to 140 nm. The thickness of a transparent thin film generally refers to its optical thickness (see page 21 of the revised and enlarged first printing of Kohiyama Mitsunobu's "Basic Theory of Optics - Fresnel Coefficients, Characteristic Matrix", Optronics Co., Ltd., February 25, 2011). In this specification, the optical thickness L0 of the light-transmitting thin film refers to the value derived 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 of the light-transmitting thin film, etc. 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 a 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 considering 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 the air is the 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 raw material constituting the light-transmitting thin film. For example, when the light-transmitting thin film is made of magnesium fluoride, the refractive index of magnesium fluoride, 1.38, is used as the refractive index of the light-transmitting thin film. Also, when the light-transmitting thin film is made of silicon dioxide, the refractive index of silicon dioxide, 1.47, is used as the refractive index of the light-transmitting thin film.

[0043] The L value derived from the above formula (2) is the ratio (L1 / L0) of the physical thickness L1 (nm) of the light-transmitting thin film to the optical 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, 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 inverse to each other as shown in Fig. 3, 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] The light emitting device of the third embodiment includes a wavelength conversion member including a light-transmitting thin film that 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 light-transmitting thin film that is a single layer with a physical film thickness L1 in the range of 250 nm to 330 nm on the light output side of the ceramic composite, the change in chromaticity due to the directional angle can be reduced and the orientation chromaticity characteristics can be improved. In this specification, when the light emitting device is viewed from the normal direction, that is, when viewed from a direction perpendicular to the light emitting surface of the wavelength conversion member that is the light emitting surface of the light emitting device, the directional angle is called 0 degrees. The direction of the directional angle of 0 degrees is a direction parallel to the optical axis of the light emitting device. The angle inclined from the directional angle of 0 degrees to the horizontal direction with respect to the light emitting surface of the light emitting device is called the directional angle θ degrees. The chromaticity of the emitted color for each directional angle may be called "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: Commission internationale de l'Eclairage) 1931 chromaticity diagram. The difference in orientation chromaticity for each directivity angle is sometimes called the "orientation chromaticity characteristic." The chromaticity coordinates (x0, y0) on the CIE chromaticity diagram for a directivity angle of 0 degrees are expressed, and the average values ​​of the x-coordinate and the y-coordinate of the emitted color due to changes in directivity angle plus θ degrees and directivity angle minus θ degrees are expressed as the orientation chromaticity coordinates (x θ , y θ ) The positive θ degrees and the negative θ degrees are specifically either positive 30 degrees and negative 30 degrees, positive 45 degrees and negative 45 degrees, or positive 60 degrees and negative 60 degrees. "Good orientation chromaticity characteristics" refers to the difference between the x-coordinate x0 at a directional angle of 0 degrees and the light distribution chromaticity coordinate x at a directional angle of θ degrees. θ This means that the difference Δx (absolute value) between the y coordinate y0 at a directional angle of 0 degrees and the y coordinate y0 at a directional angle of θ degrees is small, and the change in chromaticity is small even when the directional angle is changed. θIt is preferable that the difference Δy (absolute value) between the luminous color and the luminous color (hereinafter, sometimes referred to as "difference Δy in orientation chromaticity") is small. "Poor orientation chromaticity characteristics" means that the difference Δx in orientation chromaticity of the luminous color due to the change in directional angle is large, and a change in chromaticity occurs when the directional angle changes. In order to improve the orientation chromaticity characteristics, the physical film thickness L1 of the light-transmitting 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 aspect may be provided with a light-transmitting thin film having an L value, which will be described later, in the range of 2.5 to 3.5.

[0045] 4 is an image diagram showing the directivity angle for the light emitting device 100. When the light emitting device 100 is viewed from the normal direction, that is, when viewed from a directivity angle of 0 degrees (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 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 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 becomes larger, that is, as the directivity angle approaches the directivity angle plus 90 degrees (θ=+90° in FIG. 4) or the directivity angle approaches minus 90 degrees (θ=−90° in FIG. 4). Here, a directional angle of plus θ degrees (+θ°) is an angle inclined θ degrees horizontally from the light-emitting surface of the light-emitting device, with a directional angle of 0 degrees (0°) as the center, and a directional angle of minus θ degrees (-θ°) is an angle inclined θ degrees horizontally from the light-emitting surface of the light-emitting device, on the opposite side of a line centered on a directional angle of 0 degrees from a directional angle of plus θ degrees (+θ°).

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

[0047] Next, a case will be described where the angle of inclination from the light emitting surface of the light emitting device to the horizontal direction from a directivity angle of 0 degrees (θ=0° in FIG. 4) parallel to the optical axis z, that is, the directivity angle, changes. 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, a directivity angle of plus 60 degrees and a directivity angle of minus 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 (for example, emission with an emission peak wavelength of around 550 nm) is lower than that of the light-emitting element (for example, emission with an emission peak wavelength of around 450 nm). That is, compared to when the wavelength conversion member does not include a translucent thin film, 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 plus 60 degrees and a directivity angle of minus 60 degrees. Furthermore, when the wavelength conversion member includes a translucent thin film, the emission of the inorganic phosphor tends to be more difficult to be emitted at a directivity angle of plus 60 degrees and a directivity angle of minus 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 has a translucent thin film that satisfies specific conditions, when the wavelength exceeds 470 nm, the transmittance of the wavelength conversion member with the translucent thin film is lower than when the directivity angle is 0 degrees (0°), and it is difficult for the inorganic phosphor to emit light. As described above, when the angle of inclination from the directivity angle of 0° to the horizontal direction becomes larger, for example, when the directivity angle changes from 0 degrees to plus 90 degrees or minus 90 degrees (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, there is a tendency for the emission of inorganic phosphor light in the range of 510 nm or more and 570 nm or less to be 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 to plus 60 degrees or minus 60 degrees, the light from the light-emitting element, whose emission peak wavelength is in the range of 380 nm or more and 500 nm or less, and the light emitted from the inorganic phosphor, whose emission peak wavelength is in the range of 510 nm or more and 570 nm or less and which is difficult to transmit by the translucent thin film, are mixed. Therefore, even when the directivity angle changes from 0 degrees to plus 60 degrees or minus 60 degrees, only the light emitted from the inorganic phosphor becomes stronger, 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, and the orientation chromaticity characteristics are improved. In this way, it is believed that under certain conditions, the degree of color mixing between the inorganic phosphor's light emission and the light-emitting element's light emission will be the same in the direction of a directivity angle of 0 degrees, as well as in the direction of a directivity angle of +60 degrees or -60 degrees, and that the change in chromaticity will be small even if the directivity angle is changed.

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

[0049] Fig. 6 is an image diagram showing a schematic enlargement of a part of the wavelength conversion member of the light emitting device. The enlarged scales of Fig. 3 and Fig. 6 may not be the same. When the L value for 550 nm derived from the above formula (2) approaches 3.0, the phase of the second reflected wave Rw2 generated at the interface If2 between the light-transmitting thin film 32 and the air A for light in the range of 380 nm to 500 nm is shifted from the phase of the first reflected wave Rw1 generated at the interface If1 between the ceramic composite 31 and the light-transmitting thin film 32. As a result, the amount of light reflected within the wavelength conversion member 30 becomes greater than when the L value of the light-transmitting thin film 32 approaches 1.0, and the amount of light transmitted is reduced compared to 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 part of the light emitted from the light emitting device is reduced by reflection, so that the emission of light in the range of 380 nm to 500 nm, which is likely to be 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 likely to be emitted from the light emitting device, is reduced. When a light-emitting device is provided with a light-transmitting 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 making it possible to reduce color unevenness due to changes in the directivity angle and improve the orientation chromaticity characteristics.

[0050] The light emitting device of the fifth aspect preferably includes a wavelength conversion member including a light-transmitting thin film made of fluoride or silicon dioxide, and emits light satisfying a first transmittance difference T1 calculated based on the following formula (3) obtained by subtracting a difference in transmittance of transmitted light from 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 a difference in transmittance of transmitted light from 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 difference being within a range of 0% to 25%. The light emitting device may emit light satisfying a second transmittance difference T2 calculated based on the formula (4) described later being within a 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 with 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 with a directivity angle of 0 degrees. The directivity angle of 0 degrees is the angle perpendicular to the light-emitting surface, and 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.)

[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 is transmitted through the wavelength conversion member.

[0052] The intensity of the transmitted light from the light emitting surface of the wavelength conversion member varies depending on the wavelength and directional angle of the transmitted light. If it is possible to emit light from a light emitting device 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 the transmitted light from the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element with a directional angle of 0 degrees and the emission peak wavelength of the inorganic phosphor from the difference in transmittance of the transmitted light from the light emitting surface of the wavelength conversion member at the emission peak wavelength of the light emitting element with a directional angle of 0 degrees and the emission peak wavelength of the inorganic phosphor, even if the directional angle changes, the change in the orientation chromaticity due to the change in the directional angle is small, 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 when the directivity angle is 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 at 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 at the emission peak wavelength of the light emitting element, which tends to be high at a directivity angle close to 0 degrees, and the orientation chromaticity characteristics of the light emitted by the light emitting device will be improved.

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

[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 device increases at a directivity angle close to 0 degrees, and the transmittance of light of the emission peak wavelength of the light emitting device, which tends to increase at a directivity angle close to 0 degrees, further increases. The light emitted by the light emitting device, in which the first transmittance difference T1 is less than 0% or exceeds 25%, exhibits a large change in chromaticity and poor orientation chromaticity characteristics. In addition, the light emitted by the light emitting device, in which the value of the first transmittance difference T1 is less than 0% or exceeds 25%, exhibits a large change in chromaticity and poor orientation chromaticity characteristics, when the directivity angle is close to plus 60 degrees or minus 60 degrees, the transmittance of light of the emission peak wavelength of the inorganic phosphor increases at a directivity angle close to plus 60 degrees or minus 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, causing a change in chromaticity and poor orientation chromaticity characteristics.

[0056] The light emitting device of the fifth aspect preferably includes a wavelength conversion member including a light-transmitting thin film made of fluoride or silicon dioxide, and emits light satisfying a second transmittance difference T2 calculated based on the following formula (4) obtained by subtracting the difference in transmittance of transmitted light from 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 from the light emitting surface of the wavelength conversion 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 a range of -3% to 10%. The light emitting device may emit light satisfying a first transmittance difference T1 calculated based on the formula (3) is within a 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 with 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 minus 3% or more and 10% or less, even if the directivity angle changes, the change in chromaticity due to the change in 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 minus 2% or more and 8% or less, or may be within the range of minus 1.5% or more and 5% or less. The second transmittance difference T2 of the light emitted by the light emitting device is preferably within the range of minus 1.2% or more and 4.5% or less. If the second transmittance difference T2 of the emission of the light emitting device is within the range of minus 3% or more and 10% or less, the transmittance of light of 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 of 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 emission of the light emitting device. Also, if the value of the second transmittance difference T2 of the emission of the light emitting device is within the range of minus 3% or more and 10% or less, the transmittance of light of the emission peak wavelength of the light emitting element increases at a directivity angle close to plus 30 degrees or minus 30 degrees, maintaining a balance with the transmittance of light of 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 emission of 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. If 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 cancelled by the second reflected wave, which has an opposite phase, generated at the interface between the light-transmitting 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.

[0059] When the light-transmitting thin film is a single layer, the refractive index ratio (r1 / r2) between the refractive index r1 of the ceramic composite and the refractive index r2 of the light-transmitting thin film is preferably within a range of 1.18 to 1.41, and may be within a range of 1.20 to 1.40, 1.25 to 1.35, or 1.28 to 1.32. If the refractive index ratio (r1 / r2) between the refractive index r1 of the ceramic composite and the refractive index r2 of the light-transmitting thin film is within a range of 1.18 to 1.41, reflection at the interface between the ceramic composite and the light-transmitting thin film is canceled by reflection at the interface between the light-transmitting 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, the light-transmitting thin film 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, and when the light-transmitting thin film has two or more layers, the first layer and the second layer are alternately laminated to form a multilayer film. 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 of the light-transmitting thin film, which is a single layer.

[0061] In the light emitting device of the 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 a third transmittance difference T3 calculated based on the following formula (5) obtained by subtracting the difference in transmittance of transmitted light from 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 from the light emitting surface of the wavelength conversion member at a directivity angle of +45 degrees or -45 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 emit light that satisfies 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 with 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 with 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 defined as the same as the 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 the first layer and the 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 light-transmitting thin film When the light-transmitting thin film is a single layer, the light-transmitting thin film can be manufactured by a chemical vapor deposition method or a physical vapor deposition method. Examples of the physical vapor deposition method include an electron beam vapor deposition method, a resistance heating vapor deposition method, an ion plating method, and a sputtering method. The light-transmitting thin film is preferably formed by 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 in the range of 25°C to 400°C by resistance heating vapor deposition. 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, members constituting the light emitting device other than the light emitting element and the wavelength conversion member will be described.

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

[0066] adhesive layer An adhesive layer is interposed between the light emitting element and the wavelength conversion member, and fixes 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 Device Examples of semiconductor elements that are provided in a light-emitting device as needed include transistors for controlling light-emitting elements, and protective elements for preventing the light-emitting elements from being destroyed or their performance from deteriorating due to application of excessive voltage. Examples of protective elements include Zener diodes and capacitors.

[0068] Covering material The material of the covering member is preferably an insulating material. More specifically, it may be a phenol resin, an epoxy resin, a bismaleimide triazine resin (BT resin), a polyphthalamide (PPA) resin, or a silicone resin. The covering member may contain at least one additive selected from the group consisting of a colorant, a phosphor, and a filler, if necessary.

[0069] Conductive material The conductive member may be a bump, and the material of the bump may be Au or an alloy thereof, and other conductive members may be eutectic solder (Au-Sn), Pb-Sn, lead-free solder, or the like.

[0070] The emission color of the light emitting device is expressed as the average value of the x-coordinate x0 of the emission color of the light emitting device at a directivity angle of 0 degrees, the x-coordinate x1 of the emission color of the light emitting device at a directivity angle of +60 degrees, and the x-coordinate x2 of the emission color of the light emitting device at a directivity angle of -60 degrees in the chromaticity coordinates of the CIE 1931 chromaticity diagram. 60 The absolute value of the difference Δx between the directional angles of the light emitted by the light emitting device and the chromaticity of the light emitted by the light emitting device (hereinafter also referred to as the "difference Δx in orientation chromaticity") is 0.012 or less. If the absolute value of the difference Δx between the directional angles of the light emitted by the light emitting device is 0.012 or less, the change in chromaticity of the light emitted by the light emitting device is small even if the directional angle changes, and the orientation chromaticity characteristics can be improved. 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 coordinate of the CIE 1931 chromaticity diagram, which is the average value of the y coordinate y0 of the luminous color of the light emitting device at a directivity angle of 0 degrees, the y coordinate y1 of the luminous color of the light emitting device at a directivity angle of +60 degrees, and the y coordinate y2 of the luminous color of the light emitting device at a directivity angle of - 60 The absolute value of the difference Δy between the directional chromaticity and the directional chromaticity (hereinafter also referred to as "difference Δy in orientation chromaticity") 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 directional chromaticity and the directional chromaticity of the light emitting 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 color of the light emitting device is small, and the orientation chromaticity characteristics can be improved.

[0072] Method for manufacturing a light emitting device An example of a method for manufacturing a light emitting device will be described. For details, refer to, for example, the disclosures of JP 2014-112635 A or JP 2017-117912 A. 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 as 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 coating member.

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

[0074] Bonding process between light emitting element and wavelength conversion material In the step of adhering the light emitting element and the wavelength conversion member, the wavelength conversion member is opposed to the light emitting surface of the light emitting element, and the wavelength conversion member is bonded onto the light emitting element by an adhesive layer.

[0075] Forming process of the covering member In the step of forming the covering member, the side surfaces of the light emitting element and the wavelength conversion member except for the light emitting surface are covered with the composition for the covering member, and a covering member is formed on the side surfaces of the light emitting element and the wavelength conversion member except for 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. EXAMPLES

[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] Manufacture 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 represented by the following formula 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 the aluminum oxide particles. The mixture of raw materials is filled into a mold and pressurized to 5 MPa (51 kgf / cm 2 A cylindrical molded body with a diameter of 65 mm and a thickness of 15 mm was formed at a pressure of 176 MPa. The obtained molded body was placed in a packaging container and vacuum-packed, and then subjected to CIP at 176 MPa using a cold isostatic pressurizing device (manufactured by Kobe Steel, Ltd. (KOBELCO)) to obtain a molded body. The obtained compact was subjected to primary firing at a temperature of 1650° C. in an air atmosphere (0.101 MPa, oxygen concentration 20% by volume) using a firing furnace (manufactured by Marusho Denki Co., Ltd.) to obtain a first sintered body. The first sintered body obtained was subjected to secondary firing by HIP at a temperature of 1650°C and a pressure of 195 MPa for 2 hours in a nitrogen gas atmosphere (99.99% by volume or more) using nitrogen gas as a pressure medium using a hot isostatic pressing (HIP) device (manufactured by Kobe Steel, Ltd. (KOBELCO)), to obtain a second sintered body. This second sintered body was cut into a predetermined shape and size using a wire saw, and the surface of 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 the ceramic composite A was 1.78. The refractive index r1 of the ceramic composite A was determined by the refractive index of the rare earth aluminate phosphor in the ceramic composite of 1.82, the content of 30 mass%, and the true density of 4.77 g / cm. 3 The refractive index of aluminum oxide is 1.77, the content is 70 mass% and the true density is 3.98 g / cm 3 Therefore, it can be calculated based on the above formula (6).

[0079] Manufacture 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 represented by the following formula was prepared. A plate-shaped ceramic composite B having a thickness of 180 μm was obtained in the same manner as for ceramic composite A, except that yttrium aluminum perovskite (YAlO3:YAP) particles were prepared as the inorganic oxide, and a raw material mixture was used in which 95 mass% of the rare earth aluminate phosphor and 5 mass% of the YAP particles were mixed. The refractive index r1 of ceramic composite B was 1.83. The refractive index r1 of ceramic composite B 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 (95 mass%), and the true density of the ceramic composite (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 represented by the following formula was prepared. A plate-shaped ceramic composite C having a thickness of 180 μm was obtained in the same manner as for 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 the ceramic composite (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 The ceramic composite A and magnesium fluoride were placed in the deposition device as the deposition material, and the pressure in the deposition device was increased to 1.0×10 -4In a state where the pressure was reduced to 100 Pa, a light-transmitting thin film (MgF2 film) having a physical film thickness of 102 nm, 111 nm, or 120 nm was formed on the light-emitting surface of the ceramic composite A, which was the light-emitting side of the ceramic composite A, by using a microheater and a temperature during film formation of 300°C, by resistance heating deposition to obtain wavelength conversion members A-1 to A-3 having each physical film thickness. The physical film thickness of the light-transmitting thin film was measured by the method described later. The refractive index r2 of the light-transmitting thin film is the refractive index of MgF2, 1.38. The refractive index ratio r1 / r2 between the refractive index r1 of the ceramic composite A and the refractive index r2 of the light-transmitting thin film was 1.33.

[0082] Light emitting device manufacturing Using the obtained wavelength conversion members A-1 to A-3, the light emitting device 100 shown in Fig. 1 and Fig. 2 was fabricated as follows. The light emitting element 20 and the semiconductor element 70 were placed on the mounting substrate 10. Specifically, the light emitting element 20 was formed by stacking nitride semiconductors on a sapphire substrate, had a thickness of about 0.11 mm, a planar shape of a substantially square of about 1.0 mm square, and had an emission peak wavelength of 450 nm. The light emitting element 20 and the semiconductor element 70 were arranged in a line so that the sapphire substrate side, which is a semiconductor growth substrate, became the light emitting surface, and were flip-chip mounted on the conductive pattern formed on the mounting substrate 10 using the conductive member 60 made of Au. Next, silicone resin was placed as adhesive 40 on the upper surface of the light-emitting element 20 to bond the wavelength conversion member 30, which was formed into a plate-like shape from each of the ceramic composites of the examples and comparative examples, 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 having 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 produced in the same manner as in Example A-1, except that a ceramic composite A not formed with a light-transmitting thin film (physical 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 translucent thin film (MgF2 film) with a physical 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 translucent thin film (MgF2 film) had a physical 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 In a state where the pressure was reduced to 100 Pa, a light-transmitting thin film (MgF2 film) having a physical thickness of 85 nm, 88 nm, 103 nm, 113 nm, and 122 nm was formed on the light-emitting surface of the ceramic composite B, which is the light-emitting side of the ceramic composite B, by resistance heating deposition using a microheater and a temperature during film formation of 300 ° C., to obtain wavelength conversion members B-1 to B-5 having each physical thickness. The physical thickness of the light-transmitting thin film was measured by the method described later. Except for using these wavelength conversion members, the light-emitting devices of Examples B-1 to B-5 were produced in the same manner as in Example A-1. The refractive index r2 of the light-transmitting thin film is the refractive index of MgF2, 1.38. The refractive index ratio r1 / r2 between the refractive index r1 of the ceramic composite B and the refractive index r2 of the light-transmitting thin film was 1.33.

[0086] Light emitting device of comparative example b'-1 A light emitting device of Comparative Example b'-1 was produced in the same manner as in Example B-1, except that a ceramic composite B not formed with a light-transmitting thin film (physical 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 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 the wavelength conversion member b'-2 with a translucent thin film (MgF2 film) with a physical thickness of 205 nm was used.

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

[0089] Light emitting device of comparative example c'-1 A light emitting device of Comparative Example c'-1 was produced in the same manner as in Example C-1, except that a ceramic composite C not having a light-transmitting thin film (physical 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) having a physical 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 the wavelength conversion member c'-2 having a translucent thin film (MgF2 film) having a physical thickness of 148 nm was used.

[0091] The light-transmitting thin film of each wavelength conversion member used in the Examples and Comparative Examples and each light-emitting device of the Examples and Comparative Examples were evaluated as follows. Each light-emitting device was measured by passing a constant current of 350 mA. The results are shown in Tables 1 to 3.

[0092] Physical thickness of the transparent 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 taken 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 the ceramic composites A to C was 550 nm, and the refractive index of the light-transmitting thin film was 1.38 for MgF2 when the light-transmitting thin film was an MgF2 film made of MgF2. Also, the refractive index of SiO2 was 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 of the light-emitting devices in the examples and comparative examples, the chromaticity coordinates (x, y) in the CIE 1931 chromaticity diagram were determined using a light 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 The total luminous flux of each light emitting device of the examples and comparative examples was measured using a spectrophotometer (PMA-11, manufactured by Hamamatsu Photonics KK) using an integrating sphere. The total luminous flux of each light emitting device of the examples A-1 to A-3 and comparative examples a'-1 to a'-2 was expressed as a relative value, with 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, being taken as 100%. The total luminous flux of each light emitting device of the examples B-1 to B-5 and comparative examples b'-1 to b'-2 was expressed as a relative value, with 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, being taken as 100%. 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 thickness of the light-transmitting thin film was 0 nm, being set to 100%.

[0096] Oriented chromaticity coordinate (x θ , y θ ) A multi-spectrophotometer (PMA-11, Hamamatsu Photonics K.K.) was connected to a diffuser plate, and a rotating table with a light receiving area of ​​100 mm was placed on the rotating table, which was 100 mm away in the optical axis direction (perpendicular direction) from the diffuser plate. 2 The light emitting device was placed so that the light emitting surface faced a diffuser plate having a circular aperture of 1. A constant current of 350 mA was applied to the light emitting device, and the chromaticity coordinates (x0, y0) of the emitted color at a directivity angle of 0 degrees parallel to the optical axis were measured. 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 minus 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 platform 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 average x-coordinate x 60 The absolute value of the difference Δx (difference Δx in orientation chromaticity) was measured. θ , y θ ) is the orientation chromaticity coordinate (x θ , y θ )

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] The light-emitting devices of Examples A-1 to A-3, the light-emitting devices of Examples B-1 to B-5, and the light-emitting devices of 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 of Comparative Example a'-1, the light-emitting device of Comparative Example b'-1, and the light-emitting device of 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 have an L value of the light transmissive thin film within a range of 0.82 to 1.41, and 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, which do not have a light transmissive thin film. In the light emitting devices according to the examples, the second reflected wave generated at the interface between the light transmissive thin film and the air and the first reflected wave generated at the interface between the ceramic composite and the light transmissive thin film approach a phase in which they are in opposite phases, and the effect of the first reflected wave and the second reflected wave canceling each other out is increased, which is thought to reduce reflection within the wavelength conversion member, allowing 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] 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 physical thickness of the light-transmitting thin film exceeded 140 nm, and the L value exceeded 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 phase of the second reflected wave generated at the interface between the light-transmitting thin film and air is shifted from the phase of the first reflected wave generated at the interface between the ceramic composite and the light-transmitting thin film, so that the effect of the first reflected wave and the second reflected wave canceling each other out is reduced, and light is reflected inside 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 do not have a light-transmitting thin film.

[0104] FIG. 7 is a diagram showing the relationship between the physical film thickness and relative luminous flux of the translucent thin film 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 is understood 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 In a state where the pressure was reduced to 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 is the light-emitting side of the ceramic composite A, using a microheater and a film-forming temperature of 300°C, to obtain a wavelength conversion member A-4 having each physical film thickness. A light-emitting device of Example A-4 was produced in the same manner as in 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 above-mentioned third to seventh aspects.

[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, using a microheater and setting the temperature during film formation at 300° C., to obtain wavelength conversion members B-6 having each physical film thickness. 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 The ceramic composite C and magnesium fluoride were placed in the deposition apparatus, and the pressure in the deposition apparatus was increased to 1.0×10 -4Under a reduced pressure of 100 Pa, a light-transmitting thin film (MgF2 film) having a physical film thickness of 254 nm, 284 nm, 293 nm, 303 nm, 314 nm, or 325 nm was formed by resistance heating deposition on the light-emitting surface of the ceramic composite C, which was the light-emitting side of the ceramic composite C, using a microheater and a film-forming temperature of 300° C., to obtain wavelength conversion members C-6 to C-11 having each physical film thickness. The 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 The ceramic composite C and magnesium fluoride were placed in the deposition apparatus, and the pressure in the deposition apparatus 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 203 nm and 353 nm was formed by resistance heating deposition on the light-emitting surface of the ceramic composite C, which was the light-emitting side of the ceramic composite C, using a microheater and a film-forming temperature of 300° C., to obtain wavelength conversion members c'-3 and c'-4 having 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 represented by the following formula was prepared. A plate-shaped ceramic composite D having a thickness of 180 μm was obtained in the same manner as for ceramic composite A, except that a raw material mixture was used in which 10 mass% of the rare earth aluminate phosphor was mixed with 90 mass% of the aluminum oxide particles used in ceramic composite A. 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 the rare earth aluminate phosphor in the ceramic composite (10 mass%), and the true density of the ceramic composite (4.69 g / cm). 3The refractive index of aluminum oxide is 1.76, the content is 90 mass% and the true density is 3.98 g / cm 3 Therefore, it can be calculated based on the above formula (6).

[0110] Manufacturing of wavelength conversion materials The ceramic composite D and silicon dioxide were placed in the deposition apparatus, and the pressure in the deposition apparatus was increased to 1.0×10 -4 With the pressure reduced to 100 Pa, a light-transmitting thin film (SiO2 film) with physical film thicknesses of 251 nm, 279 nm, 297 nm, and 319 nm was formed by resistance heating deposition on the light-emitting surface of the ceramic composite D, which was the light-emitting side of the ceramic composite D, using a microheater and a film-forming temperature of 300°C, to obtain wavelength conversion members D-1 to D-4 with each physical film thickness. The refractive index r2 of the light-transmitting thin film is the refractive index of SiO2, 1.47. The refractive index ratio r1 / r2 between the refractive index r1 of the ceramic composite D and the refractive index r2 of the light-transmitting 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 produced in the same manner as in Example D-1, except that a ceramic composite D not having a light-transmitting thin film (a physical thickness of a SiO2 film: 0 nm) 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 (SiO2 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. Each of the light-emitting devices of Comparative Examples d'-2 to d'-4 was produced 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 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 examples and comparative examples 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 light-transmitting thin film was a single layer of 250 nm or more and 330 nm or less, and the absolute value of the orientation chromaticity difference Δx for the light emitted by each light-emitting device was 0.012 or less, the orientation chromaticity difference Δx due to the change in directional angle was small, the change in chromaticity due to the 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 light-transmitting thin film was within the range of 2.5 or more and 3.5 or less, and the absolute value of the orientation chromaticity difference Δx of the light emitted by each light-emitting device was 0.012 or less, the orientation chromaticity difference Δx due to the change in directional angle was small, the change in chromaticity due to the directional angle was reduced, and the orientation chromaticity characteristics were good.

[0119] In each of 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 addition, in each of the light-emitting devices according to Comparative Example c'-4 and Comparative Example d'-4, the physical thickness of the light-transmitting thin film exceeded 340 nm, and the L value exceeded 3.5. In the light emission of each of the light-emitting devices according to Comparative Examples c'-3 to c'-4 and Comparative Examples d'-1 to d'-4, the absolute value of the difference Δx in the orientation chromaticity exceeded 0.012, and the difference Δx in the orientation chromaticity of the emission color due to the change in the directivity angle was large, and the chromaticity changed due to the directivity angle, and the orientation chromaticity characteristics were poor.

[0120] Fig. 8 is a graph showing the relationship between the directional 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 light-transmitting 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 light-transmitting thin film is 0 nm. Fig. 9 is a graph showing the relationship between the directional 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 light-transmitting thin film is 304 nm, and the light emitted by the light-emitting device according to Comparative Example b'-1, in which the physical thickness of the light-transmitting thin film is 0 nm. Fig. 10 is a graph showing the relationship between the directional 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 light-transmitting thin film is 293 nm, and the light emitted by the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the light-transmitting 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 light-transmitting thin film is 279 nm, and the light emitted by the light-emitting device according to Comparative Example d'-1, in which the physical thickness of the light-transmitting thin film is 0 nm. As shown in Figs. 8 to 11, the light emitted by the light-emitting device according to the example has 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 plus 60 degrees or minus 60 degrees, and in the graph showing the relationship between the directional angle and the difference Δx in the orientation chromaticity, even when the directional angle is large, the curve shape is closer to a horizontal straight line, 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). 60 The results are shown in Table 6 together 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 transmittance at an 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-60Average transmittance of rare earth aluminate phosphor at emission peak wavelength of 550 nm with a directivity angle of plus 60 degrees and a directivity angle of minus 60 degrees. T C-30 Average transmittance at an 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 transmittance of rare earth aluminate phosphor at emission peak wavelength of 550 nm with a directivity angle of plus 30 degrees and a directivity angle of minus 30 degrees. T C-45 Average 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 transmittance of rare earth aluminate phosphor at emission peak wavelength of 550 nm with a directivity angle of plus 45 degrees and a directivity angle of minus 45 degrees. T C-0 Transmittance of a light-emitting element with a directivity angle of 0 degrees at a peak emission 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] Each of the light emitting devices according to Examples C-6, C-7, C-9, and C-11 emitted light satisfying the following: first transmittance difference T1 was within the range of 0% to 25%, second transmittance difference T2 was within the range of -3% to 10%, and third transmittance difference T3 was within the range of 0% to 20%. The light emitted by each of the light emitting devices according to Examples C-6, C-7, C-9, and C-11 had an absolute value of 0.012 or less in the difference Δx in the orientation chromaticity, a small difference Δx in the orientation chromaticity, a small change in chromaticity due to the directional angle, and good orientation 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 minus 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 directional angle and the difference Δx in the orientation chromaticity of the light emitted by the light-emitting device according to Example C-6, in which the physical thickness of the light-transmitting thin film is 254 nm, and the light emitted by the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the light-transmitting thin film is 0 nm. Fig. 13 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 C-7, in which the physical thickness of the light-transmitting thin film is 284 nm, and the light emitted by the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the light-transmitting thin film is 0 nm. Fig. 14 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 C-9, in which the physical thickness of the light-transmitting thin film is 303 nm, and the light emitted by the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the light-transmitting thin film is 0 nm. Fig. 15 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 C-11, in which the physical thickness of the light-transmitting thin film is 325 nm, and the light emitted by the light-emitting device according to Comparative Example c'-1, in which the physical thickness of the light-transmitting thin film is 0 nm. Fig. 16 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 Comparative Example c'-1, in which the physical thickness of the light-transmitting thin film is 0 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.

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

[0127] As shown in FIG. 16, when the directional angle of the light emitted by the light emitting device according to the comparative example was 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, an illumination device for general illumination, 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 transmissive thin film, 40: adhesive layer, 50: coating 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 a light emission side of the ceramic composite and having a refractive index smaller than a refractive index of the ceramic composite; a physical thickness of the light-transmitting thin film being a single layer within a range of 82 nm to 140 nm, and the light-transmitting thin film being 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.

2. The optical thickness L of the transparent thin film is calculated from the following formula (1): ０ The physical thickness L of the transparent thin film １ The light emitting device according to claim 1, wherein the L value, which is a ratio of the above values, derived from the following formula (2) is within a range of 0.82 to 1.41: L ０ = Emission peak wavelength (λ) (nm) of inorganic phosphor ÷ (4 × refractive index of light-transmitting thin film) (1) L = Physical thickness of light-transmitting film L １ (nm)÷L ０ (2)

3. 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 a light emission side of the ceramic composite and having a refractive index smaller than a refractive index of the ceramic composite; The physical thickness of the light-transmitting thin film is a single layer within a range of 250 nm to 330 nm, A light-emitting device, wherein the light-transmitting thin film is made of silicon dioxide or 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.

4. 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 a light emission side of the ceramic composite and having a refractive index smaller than a refractive index of the ceramic composite; the light-transmitting thin film is made of silicon dioxide or 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; A light emitting device that emits light that satisfies at least one of the following conditions: a first transmittance difference T1 calculated based on the following formula (3) is within a range of 0% or more and 25% or less; and a second transmittance difference T2 calculated based on the following formula (4) is within a range of -3% or more and 10% or less. 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 having 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－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 with 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 plus 60 degrees and the directivity angle of minus 60 degrees are angles of plus 60 degrees and minus 60 degrees from the angle perpendicular to the light-emitting surface toward the light-emitting surface with a directivity angle of 0 degrees as the center, 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 a directivity angle of 0 degrees as the center.)

5. 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 a light emission side of the ceramic composite and having a refractive index smaller than a refractive index of the ceramic composite; the light-transmitting thin film is a single layer 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, or made of silicon dioxide; In the chromaticity coordinates in the CIE 1931 chromaticity diagram, the x-coordinate x of the luminous color of the light emitting device at a directivity angle of 0 degrees ０ and an x-coordinate x , which is an average value of the x-coordinate of the luminous color of the light emitting device at a directional angle of +60 degrees and a directional angle of -60 degrees, which are angles of +60 degrees and -60 degrees from a perpendicular angle to the light emitting surface with a directional angle of 0 degrees as the center toward the light emitting surface. ６０ The absolute value of the difference Δx between the light emitting diode and the light emitting diode is 0.012 or less.

6. The light emitting device according to claim 4 , wherein the light transmissive thin film is a single layer.

7. The fluoride is MgF ２ , CaF ２ , SrF ２ , AlF ３ , Na ３ AlF ６ , Na ５ A ３ F1 ４ 7. The light emitting device according to claim 1, comprising at least one selected from the group consisting of NaF and LiF.

8. 8. A light emitting device according to claim 1, wherein said inorganic phosphor is a rare earth aluminate phosphor.

9. The light emitting device according to claim 8 , wherein the ceramic composite has a refractive index r1 in the range of 1.76 to 1.

85.

10. The light emitting device according to claim 1 , wherein the refractive index r2 of the light transmissive thin film is within a range of 1.32 to 1.

48.

11. 11. The light emitting device according to claim 10, wherein a refractive index ratio (r1 / r2) between a refractive index r1 of the ceramic composite and a refractive index r2 of the light transmissive thin film is within a range of 1.18 to 1.

41.

12. 9. The light emitting device according to claim 8, wherein the rare earth aluminate phosphor has a composition represented by the following formula (I): (Ln) １ １－ａ Yes ａ ) ３ (Al) ｃ Ga ｂ ) ５ O １２ (I) (In the above formula (I), Ln １ is at least one selected from the group consisting of Y, Gd, Lu and Tb, and a, b and c satisfy 0<a≦0.22, 0≦b≦0.4, 0<c≦1.1, 0.9≦b+c≦1.

1.

13. 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 13. The light emitting device of claim 1, further comprising an oxide which may include:

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