Wavelength conversion component

Abstract

To provide a wavelength conversion component that improves the efficiency of light extraction. [Solution] The wavelength conversion member according to the embodiment comprises a light-reflective substrate, a phosphor layer disposed on the substrate and having phosphor particles, oxide particles attached to the phosphor particles, and a coating film containing silicon oxide that covers the phosphor particles and the oxide particles, wherein the material of the oxide particles is different from the material of the coating film, and the attenuation coefficient of the coating film is 1.0 × 10 -5 It is less than.

Description

[Technical Field]

[0001] The embodiment relates to a wavelength conversion member. [Background technology]

[0002] Phosphor components are sometimes manufactured using the ALD (Atomic Layer Deposition) method. For example, Patent Document 1 describes coating a translucent phosphor plate with a powder phosphor containing oxide particles using a coating layer such as an ALD layer or a sol-gel layer. Patent Document 2 describes reducing the refractive index difference between the oxide particles and the coating layer by using the same oxide material, thereby preventing unwanted scattering. Patent Document 2 also describes how using the same oxide material for the oxide particles and the coating layer results in the same thermal expansion coefficient, effectively preventing peeling of the two. However, when wavelength conversion members are manufactured using the above methods, there is room for improvement in improving the efficiency of light extraction from the wavelength conversion member when light is incident on it. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-247067 [Patent Document 2] Japanese Patent Publication No. 2016-100485 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The embodiment aims to provide a wavelength conversion member with improved light extraction efficiency. [Means for solving the problem]

[0005] The wavelength conversion member according to this embodiment comprises a light-reflective substrate, a phosphor layer disposed on the substrate and having phosphor particles, oxide particles attached to the phosphor particles, and a coating film containing silicon oxide that covers the phosphor particles and the oxide particles, wherein the material of the oxide particles is different from the material of the coating film, and the attenuation coefficient of the coating film is 1.0 × 10 -5 It is less than. [Effects of the Invention]

[0006] According to the embodiment, a wavelength conversion member with improved light extraction efficiency can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic enlarged cross-sectional view illustrating the configuration of the wavelength conversion member according to the embodiment. [Figure 2] This is a schematic cross-sectional view illustrating the area ratio between regions where phosphorescent particles are present and regions where they are missing. [Figure 3] This is a schematic top view illustrating the area ratio between regions where phosphorescent particles are present and regions where they are missing. [Figure 4] This is an approximation line in Cx used to determine the light extraction efficiency. [Figure 5] This is an approximation line for Cy used to determine the light extraction efficiency. [Figure 6] These are the conditions and results for Example 1, Example 2, and Comparative Example 1. [Figure 7] These are photographs of the wavelength conversion members of Example 1 and Comparative Example 1 before and after irradiation with blue laser light. [Figure 8] This is a photograph of the wavelength conversion member of Example 1 when blue light is irradiated from a planar light source. [Figure 9] This is a photograph of the wavelength conversion member of Example 2 when blue light is irradiated from a planar light source. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described while referring to the drawings. Note that each drawing is schematic and conceptual, and is appropriately emphasized and simplified. Also, even for the same components, the dimensional ratios, positional relationships, numbers, etc. do not necessarily exactly match between the drawings. In addition, as a cross-sectional view, there may be a case where an end view showing only the cut surface is shown.

[0009] FIG. 1 is a schematic enlarged cross-sectional view for explaining the configuration of the wavelength conversion member 100 according to the embodiment. As shown in FIG. 1, the wavelength conversion member 100 according to the embodiment includes a substrate 10, a reflective film 11, and a phosphor layer 20.

[0010] The substrate 10 has light reflectivity and heat dissipation properties. Examples of the material of the substrate 10 include metals such as gold, silver, copper, iron, nickel, chromium, aluminum, titanium, tantalum, tungsten, cobalt, ruthenium, tin, zinc, lead, etc. or alloys thereof (for example, as an aluminum alloy, an alloy of aluminum and a platinum group metal such as copper, silver, platinum, etc.).

[0011] The reflective film 11 is provided between the substrate 10 and the phosphor layer 20, and is a member that reflects light incident from the phosphor layer 20 side. The reflective film 11 can use a single layer made of metal, a multilayer film made of metal, or a multilayer film (dielectric multilayer film) in which a plurality of two or more dielectrics are laminated. As the dielectric multilayer film, for example, a DBR (distributed Bragg reflector) film can be used. Among these, it is preferable to use a film including a dielectric multilayer film. If it is a dielectric multilayer film, light can be reflected efficiently.

[0012] Examples of the material of the reflective film 11 include metals such as gold, silver, copper, iron, nickel, chromium, aluminum, titanium, tantalum, tungsten, cobalt, ruthenium, tin, zinc, lead, etc. or alloys thereof (for example, as an aluminum alloy, an alloy of aluminum and a platinum group metal such as copper, silver, platinum, etc.).

[0013] In addition, examples of the dielectric used as the reflective film 11 include oxides or nitrides containing at least one element selected from the group consisting of Si (silicon), Ti (titanium), Zr (zirconium), Nb (niobium), Ta (tantalum), and Al (aluminum).

[0014] The thickness of the reflective film 11 is, for example, about 0.1 μm to several tens of μm, preferably about 0.1 μm to 10 μm, and more preferably about 0.3 μm to 7 μm.

[0015] As shown in FIG. 1, the phosphor layer 20 is disposed on the substrate 10 or on the reflective film 11, and includes phosphor particles 21, oxide particles 22, and a coating film 23.

[0016] The phosphor particles 21 are excited by incident light and emit light having a longer wavelength than the incident light.

[0017] Examples of the phosphor particles 21 include YAG (Yttrium Aluminum Garnet)-based phosphors activated with cerium as an activator, nitrogen-containing calcium aluminosilicate (CaO—Al2O3—SiO2) phosphors activated with europium and / or chromium as an activator, and CASN-based phosphors, SCASN-based phosphors, silicate ((Sr, Ba)2SiO4) phosphors, α-sialon phosphors, β-sialon phosphors, etc. activated with europium, and one or more selected therefrom.

[0018] As the phosphor particles 21, it is preferable to use a material having relatively high heat resistance and little deterioration by excitation light. Suitable materials include, for example, YAG-based phosphors, LAG-based phosphors, CASN-based phosphors, SCASN-based phosphors, etc. Here, the YAG-based phosphors include those in which at least a part of Y is substituted with Tb, or those in which at least a part of Y is substituted with Lu. Also, the YAG-based phosphors may contain Gd, Ga, etc. in the composition. The preferable composition of the phosphor particles 21 is (Y, Gd, Lu)3(Al, Ga)5O 12 :Ce.

[0019] The overall thickness of the phosphor layer 20 is preferably 30 to 50 μm. This improves the light extraction efficiency.

[0020] The oxide particles 22 adhere to the phosphor particles 21 and, after firing, bond the phosphor particles 21 together. The oxide particles 22 also contain at least one material from the group consisting of Al2O3, ZrO2, HfO2, TiO2, ZnO, Ta2O5, Nb2O5, In2O3, and SnO2.

[0021] It is preferable to use a material with a thermal expansion coefficient close to that of the phosphor particles 21 or a material with low light absorption as the oxide particles 22. Suitable materials include, for example, aluminum oxide.

[0022] The coating film 23 coats the phosphor particles 21 and the oxide particles 22. The coating film 23 also coats the phosphor particles 21. The oxide particles 22 are arranged within the coating film 23. The coating film 23 also contains silicon oxide. The silicon oxide includes SiO2, SiO2, and SiO2. 1.5 Examples include the above. As a method for forming the coating film, a coating film 23 containing SiO2 or the like can be formed on the phosphor particles 21 and oxide particles 22 placed on the substrate 10 or the reflective film 11 using an ALD apparatus. After film formation, the coating film 23 is firmly fixed to the substrate 10 together with the phosphor particles 21 and oxide particles 22.

[0023] The material of the coating film 23 is different from the material of the oxide particles 22. If the material of the coating film 23 is silicon oxide, the material of the oxide particles 22 is something other than silicon oxide.

[0024] Furthermore, the attenuation coefficient of the coating film 23 in the visible light range is 1.0 × 10⁻⁶. -5 It is less than [value]. The extinction coefficient refers to the imaginary part of the complex refractive index in the visible light range and can be measured using a spectroscopic ellipsometer (e.g., VASE: manufactured by JA Woollam).

[0025] A method for manufacturing the wavelength conversion member 100 according to the embodiment will now be described. First, a substrate 10 having light reflectivity is prepared. The substrate 10 used is as described above.

[0026] A printing resin is prepared by mixing a resin, a solvent, oxide particles 22, and phosphor particles 21. The oxide particles 22 and phosphor particles 21 used are as described above. Examples of resins that can be used include ethylcellulose, epoxy resin, silicone resin, and acrylic resin. Acrylic resin is preferred because it decomposes and volatilizes easily at low temperatures. Examples of solvents that can be used include butyl carbitol acetate and terpineol. A solvent with a boiling point of 150°C or higher is preferred because it does not volatilize easily during the process.

[0027] The aforementioned printing resin is applied to the substrate 10 using a printing mask. Then, it is dried to evaporate the solvent. It is also heated to decompose and evaporate the resin. Furthermore, ozone cleaning is performed to completely remove any remaining resin. At this time, the substrate 10 and the phosphor particles 21, and the phosphor particles 21 themselves, are weakly bonded via oxide particles 22.

[0028] Next, an ALD apparatus is used to form a coating film containing SiO2 or the like, so that the coating film 23, along with the phosphor particles 21 and oxide particles 22, is firmly fixed to the substrate 10. In this way, the wavelength conversion member 100 according to the embodiment is obtained.

[0029] The light extraction efficiency will now be explained. Blue laser light is irradiated from the phosphor layer 20 side of the wavelength conversion member 100 according to the embodiment, and light containing light with a longer wavelength than the incident light, such as white light, which is excited by the phosphor particles 21, is extracted. At this time, the white light includes the mixture of light scattered from the blue light of the laser, the light emitted after the phosphor layer 20 absorbs the blue light, and the light reflected by the reflector 11. The efficiency is calculated as lm / W, where W is the radiant flux of the incident blue laser light and lm is the luminous flux of the reflected white light detected. In other words, the extraction efficiency is how many lm of white light can be extracted from the blue laser.

[0030] According to the wavelength conversion member 100 of the embodiment, since it has the above-described configuration, it is possible to improve the efficiency of extracting white light when light is incident on it.

[0031] In this case, the diameter of the phosphor particles 21 is preferably 18 μm or less, 11 μm or less, and more preferably 5 μm or less. By doing so, the phosphor particles can be densely and uniformly arranged on the substrate, and scattering from the wavelength conversion member 100 will increase, thereby further improving the light extraction efficiency.

[0032] Furthermore, the concentration of the activator contained in the phosphor particles 21 is preferably 5 mol% or less. The activator is, for example, cerium. In this way, the amount of cerium as an activator is reduced relative to the phosphor particles 21, while the amount of phosphor particles 21 is increased relative to the activator, which increases the amount of light scattering and thus improves the light extraction efficiency.

[0033] Figure 2 is a schematic cross-sectional view illustrating the area ratio between the region where phosphor particles 21 are present and the region where they are absent. Figure 3 is a schematic top view illustrating the area ratio between the region where phosphor particles 21 are present and the region where they are absent. After the ALD film is deposited, as shown in Figures 2 and 3, there are regions where phosphor particles 21 are present and regions where they are absent. At this time, blue light is irradiated from above the wavelength conversion member 100 using a planar light source, and a chromaticity profile is acquired using an imaging luminance meter (product name: ProMetric®). Relative chromaticity Cx data is extracted and analyzed using a line profile. Then, the relative chromaticity Cx of the region where phosphor particles 21 are absent is corrected to be zero, and the area of ​​the region where the relative chromaticity Cx is 85% or less of the maximum relative chromaticity Cx of the phosphor particle 21 region is defined as S0, and the area of ​​the region where it exceeds 85% is defined as S1.

[0034] In other words, as shown in Figure 3, when viewed from above, if S1 is the area of ​​the region in the phosphor layer 20 where phosphor particles 21 are present, and S0 is the area of ​​the region where phosphor particles 21 are missing, it is preferable that the value obtained by dividing S0 by (S0 + S1) is 0.05 or less. In this way, scattering from the wavelength conversion member 100 increases, and the light extraction efficiency can be further improved. Note that the gap area ratio refers to the value obtained by dividing S0 by (S0 + S1) as described above. [Examples]

[0035] The wavelength conversion member 100 according to the embodiment will be described in detail below with reference to examples. However, the wavelength conversion member 100 according to the embodiment is not limited to this embodiment.

[0036] (Example 1) First, a substrate made of reflective copper was prepared. Then, a DBR film was deposited on the substrate. In addition, a printing resin was prepared by mixing acrylic resin (KC-1300, manufactured by Kyoeisha Chemical Co., Ltd.), terpineol as a solvent, nanoalumina particles (AluC) as oxide particles, and YAG-based phosphor particles. At this time, the amount of Ce (cerium) added as an activator in the phosphor was set to 0.09 mol. The weight ratio of phosphor particles in the printing resin was set to 130. Furthermore, phosphor particles with a diameter of 18 μm were used. The diameter of the phosphor particles was measured by laser diffraction. The concentration of nanoalumina particles in the printing resin was set to 0.77 wt%.

[0037] The substrate was coated with printing resin using a printing mask. It was then dried in an oven at 150°C for 0.5 hours, followed by further drying at 180°C for another 0.5 hours to evaporate the solvent. Finally, it was baked in an oven at 250°C for 10 hours to decompose and evaporate the acrylic resin. Ozone washing was then performed to completely remove any remaining acrylic resin. The Ce concentration in the phosphor particles at this stage was 3 mol%.

[0038] Next, SiO2 was deposited as a coating film at 200°C using an ALD apparatus. The ALD film thickness was set to 0.1 μm. In this way, the wavelength conversion member of Example 1 was obtained.

[0039] (Example 2) In Example 2, the amount of Ce added as an activator in the phosphor was set to 0.03 mol. The weight ratio of phosphor particles in the printing resin was set to 350. In addition, phosphor particles with a diameter of 11 μm were used. The concentration of nanoalumina particles in the printing resin was set to 1.10 wt%. Other conditions were the same as in Example 1. In this way, the wavelength conversion member of Example 2 was obtained.

[0040] (Comparative Example 1) The weight ratio of phosphor particles in the printing resin was set to 100. The concentration of nanoalumina particles in the printing resin was set to 0.68 wt%. In addition, Al2O3 was deposited as a coating film at 100°C using an ALD apparatus. In Comparative Example 1, the material of the oxide particles is the same as the material of the coating film. Other conditions are the same as in Example 1. In this way, the wavelength conversion member of Example 2 was obtained.

[0041] The extinction coefficient, initial characteristics such as light extraction efficiency, blackening evaluation, and light emission area ratio were measured for the wavelength conversion members obtained in Example 1, Example 2, and Comparative Example 1.

[0042] The extinction coefficient was measured for the coating film using a spectroscopic ellipsometer.

[0043] The light extraction efficiency was measured as follows. Figure 4 shows the approximation line for Cx used to determine the light extraction efficiency. Figure 5 shows the approximation line for Cy used to determine the light extraction efficiency. The light extraction efficiency lm / W was converted using relative chromaticity Cx 0.316 and relative chromaticity Cy 0.318. Approximation lines for lm / W were obtained for Cx and Cy by changing the thickness of the phosphor. Then, the relative chromaticity Cx and relative chromaticity Cy obtained by actual measurement were fitted to these approximation lines, and the extraction efficiency was determined from the average value of lm / W for relative chromaticity Cx and relative chromaticity Cy.

[0044] Blackening evaluation was performed by shining a blue laser beam of 16.5 W / mm² onto the obtained wavelength conversion material. 2 The irradiation was performed at the specified power density, and the presence or absence of blackening was checked.

[0045] The percentage of missing area was calculated by irradiating a wavelength conversion material with blue light from a planar light source, acquiring a chromaticity profile with an imaging luminance meter (prometric), extracting relative chromaticity Cx data, and analyzing it using a line profile. Then, the relative chromaticity Cx of the areas where phosphor particles were missing was corrected to zero. The area of ​​the region where the relative chromaticity Cx was 85% or less of the maximum relative chromaticity Cx of the phosphor particle region was defined as S0, and the area of ​​the region where it was more than 85% was defined as S1. The value (%) was calculated by dividing S0 by (S0 + S1).

[0046] The conditions and results obtained in Example 1, Example 2, and Comparative Example 1 are shown in Figure 6. As shown in Figure 6, the extinction coefficient of the wavelength conversion members in Example 1 and Example 2 is 1.0 × 10⁻⁶. -5 It was less than 0.000001, which is below the detection limit. On the other hand, the extinction coefficient of Comparative Example 1 was 1.0 × 10⁻⁶ -5 The result was 0.000016, which is higher than that of Examples 1 and 2.

[0047] Based on the above, the light extraction efficiency of the wavelength conversion member in Example 1 was 167.6 lm / W, and the extraction efficiency of Example 2 was 167.0 lm / W. On the other hand, the light extraction efficiency of the wavelength conversion member in Comparative Example 1 was 164.2 lm / W. Therefore, the light extraction efficiencies of Examples 1 and 2 were higher than those of Comparative Example 1. Thus, the wavelength conversion members of Examples 1 and 2 were able to improve the light extraction efficiency. This is thought to be because the oxide particles are made of a different material from the coating film, resulting in greater light scattering. Furthermore, this is because the attenuation coefficient of the SiO2 coating film in Example 1 is 1.0 × 10⁻⁶. -5 This is thought to be because the concentration is less than the limit. Furthermore, this is thought to be because the concentration of nanoalumina particles in the printing resin of Example 1 and Example 2 is higher than the concentration of nanoalumina particles in the printing resin of Comparative Example 1.

[0048] Figure 7 is a photograph of the wavelength conversion member of Example 1 and Comparative Example 1 before and after being irradiated with blue laser light. In the wavelength conversion member of Example 1, as shown in Figure 7, no blackening occurred even when irradiated with blue laser light. On the other hand, in the wavelength conversion member of Comparative Example 1, blackening (the locations indicated by the arrows in the figure) occurred when irradiated with blue laser light as shown in Figure 7. Therefore, the wavelength conversion member of Example 1 was able to suppress the occurrence of blackening when irradiated with blue laser light. This is presumably because the oxide particles of Example 1 are Al2O3, the coating film is SiO2, the oxide particles and the coating film are made of different materials, the oxide particles of Comparative Example 1 are Al2O3, the coating film is Al2O3, and the oxide particles and the coating film are made of the same material. Also, this is presumably because the attenuation coefficient of SiO2 is less than 1.0×10 -5 less than. Also, in the temperature evaluation, no peeling of the phosphor layer from the substrate occurred in the wavelength conversion member of Example 1.

[0049] Figure 8 is a photograph of the wavelength conversion member of Example 1 when irradiated with blue light by a planar light source. Figure 9 is a photograph of the wavelength conversion member of Example 2 when irradiated with blue light by a planar light source. In the wavelength conversion member of Example 1, the peeling area ratio was 55%, which was a good value. Note that the black dot portions in Figure 8 are regions where the relative chromaticity Cx is 85% or less, and the rest are regions exceeding 85%. Also, in the wavelength conversion member of Example 2, the peeling area ratio was 1.1%, which was an even better value. This is presumably because the phosphor particles of Example 2 are smaller than the phosphor particles of Example 1, so the phosphor particles can be provided densely and uniformly on the substrate.

[0050] From the above, according to the wavelength conversion member according to the embodiment, the light extraction efficiency could be improved.

[0051] Also, by making the oxide particles at least one or more of the group consisting of Al2O3, ZrO2, HfO2, TiO2, ZnO, Ta2O5, Nb2O5, In2O3, SnO2, the material of the oxide particles is different from the material of the coating film, and the light extraction efficiency can be improved.

[0052] By setting the diameter of the phosphor particles to 5 μm or less, the phosphor particles can be densely and uniformly arranged on the substrate, which increases scattering from the wavelength conversion member and thus further improves the light extraction efficiency.

[0053] By keeping the concentration of the activator in the phosphor particles to 5 mol% or less, the amount of activator relative to the phosphor particles becomes smaller, while the amount of phosphor particles becomes larger relative to the activator, thereby further improving the light extraction efficiency.

[0054] The composition of the phosphor particles is (Y,Gd,Lu)3(Al,Ga)5O 12 Since it is Ce, using Ce as the activator can further improve the light extraction efficiency.

[0055] In a top view, if S1 is the area of ​​the region in the phosphor layer where phosphor particles are present, and S0 is the area of ​​the region where phosphor particles are missing, then by making the value obtained by dividing S0 by (S0 + S1) 0.05 or less, scattering from the wavelength conversion member increases, thereby further improving the light extraction efficiency.

[0056] By further incorporating a reflective film that reflects light between the substrate and the phosphor layer, light can be reflected more efficiently, further improving the light extraction efficiency.

[0057] The embodiments and their modifications described above are examples that embody the present invention, and the present invention is not limited to these embodiments and modifications. For example, the present invention also includes the addition, deletion, or modification of some components or processes in the embodiments and modifications described above. Furthermore, the embodiments and modifications described above can be implemented in combination with each other.

[0058] The present invention includes the following embodiments.

[0059] (Note 1) A substrate having light reflectivity, A phosphor layer disposed on the substrate, comprising phosphor particles, oxide particles attached to the phosphor particles, and a coating film containing silicon oxide that covers the phosphor particles and the oxide particles, Equipped with, The material of the oxide particles differs from the material of the coating film, The damping coefficient of the aforementioned coating film is 1.0 × 10 -5 A wavelength conversion component that is less than [a certain value].

[0060] (Note 2) The wavelength conversion member according to Appendix 1, wherein the oxide particles are at least one from the group consisting of Al2O3, ZrO2, HfO2, TiO2, ZnO, Ta2O5, Nb2O5, In2O3, and SnO2.

[0061] (Note 3) The wavelength conversion member according to Appendix 1 or 2, wherein the diameter of the phosphor particles is 5 μm or less.

[0062] (Note 4) The wavelength conversion member according to any one of the appendices 1 to 3, wherein the concentration of the activator contained in the phosphor particles is 5 mol% or less.

[0063] (Note 5) The composition of the aforementioned phosphor particles is (Y,Gd,Lu)3(Al,Ga)5O 12 :Ce, The activator is Ce, as described in Appendix 4, for the wavelength conversion member.

[0064] (Note 6) The wavelength conversion member according to Appendix 4, wherein, in a top view, if S1 is the area of ​​the region in the phosphor layer where the phosphor particles are present and S0 is the area of ​​the region where the phosphor particles are missing, the value obtained by dividing S0 by (S0 + S1) is 0.05 or less.

[0065] (Note 7) The wavelength conversion member according to any one of the appendices 1 to 6, further comprising a light-reflecting reflective film between the substrate and the phosphor layer. [Explanation of Symbols]

[0066] 10 base, 11 reflective film, 20 Phosphor layer, 21 Phosphor particles, 22 Oxide particles, 23 Coating film, 100 wavelength conversion member, S0: Area of ​​the region where phosphor particles are missing; S1: Area of ​​the region where phosphor particles are present.

Claims

1. A substrate having light reflectivity, A phosphor layer disposed on the substrate, comprising phosphor particles, oxide particles attached to the phosphor particles, and a coating film containing silicon oxide that covers the phosphor particles and the oxide particles, Equipped with, The material of the oxide particles differs from the material of the coating film, The damping coefficient of the coating film is 1.0 × 10 －５ A wavelength conversion component that is less than [a certain value].

2. The oxide particles are Al ２ O ３ , ZrO ２ , HfO ２ , TiO ２ , ZnO, Ta ２ O ５ , Nb ２ O ５ , In ２ O ３ , SnO ２ The wavelength conversion member according to claim 1, which is at least one or more selected from the group consisting of

3. The wavelength conversion member according to claim 1, wherein the diameter of the phosphor particles is 5 μm or less.

4. The wavelength conversion member according to claim 1, wherein the concentration of the activator contained in the phosphor particles is 5 mol% or less.

5. The composition of the aforementioned phosphor particles is (Y, Gd, Lu) ３ (Al, Ga) ５ O １２ : Ce is, The wavelength conversion member according to claim 4, wherein the activator is Ce.

6. The wavelength conversion member according to claim 4, wherein, in a top view, if S1 is the area of ​​the region in the phosphor layer where the phosphor particles are present and S0 is the area of ​​the region where the phosphor particles are missing, the value obtained by dividing S0 by (S0 + S1) is 0.05 or less.

7. The wavelength conversion member according to any one of claims 1 to 6, further comprising a light-reflecting reflective film between the substrate and the phosphor layer.

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