Wavelength conversion member and light-emitting device

Abstract

To provide a wavelength conversion member which offers higher light extraction efficiency.SOLUTION: A wavelength conversion member 1 disclosed herein comprises a tabular member 2 and a phosphor layer 3 provided on a main surface 2a of the tabular member 2, the phosphor layer 3 containing an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix. A parameter P represented by the following expression (1) is in a range of 2 to 12, inclusive: P=(1 / (D50)0.5)×A×T ...(1), where D50 (μm) represents an average particle diameter of the inorganic phosphor, A (vol.%) represents content of the inorganic phosphor in the phosphor layer 3, and T (μm) represents a thickness of the phosphor layer 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wavelength conversion member that converts the wavelength of excitation light emitted from a light source, and a light emitting device using the wavelength conversion member. [Background technology]

[0002] Conventionally, light-emitting devices using light-emitting diodes (LEDs) and laser diodes (LDs) are widely known. As an example of such a light-emitting device, the following Patent Document 1 discloses a light-emitting device in which a wavelength conversion member that absorbs part of the light from the LED and converts it to yellow light is disposed on an LED that emits blue light. This light-emitting device emits white light that is a composite light of the blue light emitted from the LED and the yellow light emitted from the wavelength conversion member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-208815 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a wavelength conversion member may be a member having a phosphor layer provided on the main surface of a plate-shaped member. Such a wavelength conversion member may be formed, for example, by applying a slurry containing a phosphor onto the main surface of the plate-shaped member and sintering it. However, such a wavelength conversion member may not be able to sufficiently increase the light extraction efficiency depending on the configuration of the phosphor layer.

[0005] An object of the present invention is to provide a wavelength conversion member that can effectively increase light extraction efficiency, a method for manufacturing the wavelength conversion member, and a light emitting device using the wavelength conversion member. [Means for solving the problem]

[0006] Various aspects of a wavelength conversion member that solves the above problems and a light emitting device that uses the wavelength conversion member will be described below.

[0007] A wavelength conversion member according to a first aspect of the present invention includes a plate-shaped member and a phosphor layer provided on a main surface of the plate-shaped member, the phosphor layer including an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix, and an average particle diameter of the inorganic phosphor is D 50 The present invention is characterized in that, when the volume percent of the inorganic phosphor in the phosphor layer is A (μm), the content of the inorganic phosphor in the phosphor layer is A (volume percent), and the thickness of the phosphor layer is T (μm), a parameter P represented by the following formula (1) is 2 or more and 12 or less.

[0008] P = (1 / (D 50 ) 0.5 )×A×T…Formula (1)

[0009] The wavelength conversion member of aspect 2 is the same as that of aspect 1, except that the inorganic phosphor has an average particle diameter D 50 However, it is preferable that the thickness is 1 μm or more and 30 μm or less.

[0010] The wavelength conversion member of aspect 3 is preferably the same as aspect 1 or 2, in which the content A of the inorganic phosphor in the phosphor layer is 20 volume % or more and 80 volume % or less.

[0011] In the wavelength conversion member of aspect 4, in any one of aspects 1 to 3, the thickness T of the phosphor layer is preferably 2 μm or more and 300 μm or less.

[0012] The wavelength conversion member of aspect 5, in any one of aspects 1 to 4, is preferably such that the inorganic matrix is ​​a glass matrix.

[0013] The wavelength conversion member of aspect 6, in any one of aspects 1 to 5, preferably has a total light transmittance of the plate-like member at a wavelength of 450 nm and a thickness of 1 mm of 70% or more and 95% or less.

[0014] The wavelength conversion member of aspect 7 is preferably any one of aspects 1 to 6, wherein the plate-like member is at least one substrate selected from the group consisting of a glass substrate, a sapphire substrate, and a translucent alumina substrate.

[0015] In the wavelength conversion member of aspect 8, in any one of aspects 1 to 7, it is preferable that the thickness of the plate-like member is 0.05 mm or more and 2 mm or less.

[0016] The wavelength conversion member of aspect 9 may be any of aspects 1 to 8, wherein the plate-shaped member has a first main surface and a second main surface facing each other, the phosphor layer is provided on the first main surface side of the plate-shaped member, and the wavelength conversion member of aspect 9 may further include a bandpass filter provided between the first main surface and the phosphor layer of the plate-shaped member or on the second main surface of the plate-shaped member.

[0017] A light emitting device according to a tenth aspect of the present invention is characterized by comprising the wavelength conversion member according to any one of the first to ninth aspects, and a light source that emits excitation light to the wavelength conversion member.

[0018] A method for producing a wavelength conversion member according to an eleventh aspect of the present invention includes the steps of: preparing a plate-shaped member; and forming a phosphor layer on a main surface of the plate-shaped member, the phosphor layer including an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix. In the step of forming the phosphor layer, 50 (μm), the content of the inorganic phosphor in the phosphor layer is A (volume %), and the thickness of the phosphor layer is T (μm). The parameter P represented by the following formula (1) is set to 2 or more and 12 or less. 50 (μm), A (volume %), and T (μm).

[0019] P = (1 / (D 50 ) 0.5 )×A×T…Formula (1) Effect of the Invention

[0020] According to the present invention, it is possible to provide a wavelength conversion member that can effectively increase the light extraction efficiency, a method for manufacturing the wavelength conversion member, and a light emitting device using the wavelength conversion member. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a wavelength conversion member according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an enlarged view of a phosphor layer constituting the wavelength conversion member according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a wavelength conversion member according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a light-emitting device according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing a modified example of a light-emitting device according to one embodiment of the present invention. [Figure 6] FIG. 6 is a graph showing the relationship between the parameter P and the fluorescence peak intensity in Examples 1 to 4 and Comparative Examples 1 and 2. [Figure 7] FIG. 7 is a graph showing the relationship between the parameter P and the fluorescence peak intensity in Examples 5 to 8 and Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0023] [Wavelength conversion material] (First embodiment) Fig. 1 is a schematic cross-sectional view showing a wavelength conversion member according to a first embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view showing an enlarged phosphor layer constituting the wavelength conversion member according to the first embodiment of the present invention.

[0024] 1, the wavelength conversion member 1 includes a plate-shaped member 2 and a phosphor layer 3. The plate-shaped member 2 has a first main surface 2a and a second main surface 2b that face each other. The phosphor layer 3 is provided on the first main surface 2a of the plate-shaped member 2.

[0025] In the wavelength conversion member 1, excitation light X emitted from the light source 10 enters the plate-shaped member 2 from the second main surface 2b side of the plate-shaped member 2. The excitation light X passes through the plate-shaped member 2, exits from the first main surface 2a side of the plate-shaped member 2, and enters the phosphor layer 3. When the phosphor layer 3 is irradiated with the excitation light X, fluorescence is emitted from the phosphor layer 3. In the wavelength conversion member 1, combined light Y of the excitation light X and the fluorescence is emitted from the phosphor layer 3.

[0026] 2, the phosphor layer 3 includes an inorganic matrix 4 and an inorganic phosphor 5. The inorganic phosphor 5 is dispersed in the inorganic matrix 4.

[0027] In the wavelength conversion member 1 of this embodiment, the average particle diameter of the inorganic phosphor 5 is D 50 It is characterized in that, when A (volume %) is the thickness (μm) of the phosphor layer 3, A is the content of the inorganic phosphor 5 in the phosphor layer 3, and T is the thickness (μm), a parameter P represented by the following formula (1) is 2 or more and 12 or less. Note that in formula (1), the content A of the inorganic phosphor 5 is multiplied by the volume ratio of the content of the inorganic phosphor 5 to the entire material in the phosphor layer 3.

[0028] P = (1 / (D 50 ) 0.5 )×A×T…Formula (1)

[0029] Conventionally, wavelength conversion members having a phosphor layer provided on the main surface of a plate-shaped member have been studied as wavelength conversion members capable of increasing the light emission intensity of light-emitting devices because the phosphor layer can be filled at a high concentration while the thickness of the phosphor layer can be made thin. However, in such wavelength conversion members, the light extraction efficiency cannot be sufficiently increased in some cases due to the configuration of the phosphor layer.

[0030] For example, in order to improve the light extraction efficiency, it is possible to prepare a thick phosphor layer by filling inorganic phosphors with small particle diameters at a high concentration. However, in reality, such a phosphor layer has a large scattering factor, which makes it difficult for light to pass through the phosphor layer, and the return light component of the fluorescent light, which is the wavelength-converted light, becomes large, and as a result, there are cases where the light extraction efficiency at the exit side cannot be sufficiently improved. Thus, when designing a phosphor layer, there are other matters to be considered besides the content of inorganic phosphors in the phosphor layer.

[0031] As a result of intensive research, the present inventor has found that in a wavelength conversion member having a phosphor layer provided on the main surface of a plate-shaped member, the interface area between an inorganic matrix such as glass and the inorganic phosphor changes depending on the particle diameter of the inorganic phosphor, and the scattering factor of the phosphor layer changes significantly. 50 They found that the thickness (μm), the content A (volume %) of the inorganic phosphor in the phosphor layer, and the thickness T (μm) of the phosphor layer are closely related to the scattering factor of the phosphor layer, and that by appropriately adjusting these factors, the light extraction efficiency of the wavelength conversion member can be effectively increased.

[0032] Specifically, in the phosphor layer 3 constituting the wavelength conversion member 1, the average particle diameter D 50 Focusing on the wavelength (μm), the content A (volume %) of inorganic phosphor 5 in phosphor layer 3, and the thickness T (μm) of phosphor layer 3, it was found that the light extraction efficiency of wavelength conversion member 1 can be effectively increased when parameter P, expressed by the above formula (1) based on these, is 2 or more and 12 or less.

[0033] In this embodiment, parameter P represented by the above formula (1) is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, particularly preferably 6 or more, and is preferably 11 or less, more preferably 10 or less, even more preferably 9 or less, still more preferably 8 or less, particularly preferably 7 or less. In this case, the light extraction efficiency in wavelength conversion member 1 can be increased even more effectively.

[0034] In this embodiment, the average particle diameter D 50 is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and is preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less.

[0035] Average particle size D of inorganic phosphor 5 50 is equal to or larger than the lower limit, the quantum efficiency can be further improved, and the luminescence intensity of the wavelength conversion member 1 can be further increased. 50 When the average particle diameter D of the inorganic phosphor 5 is equal to or less than the upper limit, the dispersibility of the inorganic phosphor 5 in the inorganic matrix 4 can be further increased, and the emission color of the wavelength conversion member 1 can be made more uniform. 50 When is within the above range, the parameter P expressed by the above formula (1) can be adjusted to a more suitable range.

[0036] In this specification, the average particle diameter D 50 refers to the particle size at which the cumulative frequency is 50 volume % in the volume-based particle size distribution measured using a laser diffraction particle size distribution measuring device.

[0037] In this embodiment, the content A of the inorganic phosphor 5 in the phosphor layer 3 is preferably 20 vol.% or more, more preferably 30 vol.% or more, even more preferably 40 vol.% or more, and preferably 80 vol.% or less, more preferably 75 vol.% or less, even more preferably 70 vol.% or less, even more preferably 67 vol.% or less, and particularly preferably 64 vol.% or less.

[0038] When the content A of the inorganic phosphor 5 in the phosphor layer 3 is equal to or greater than the above lower limit, the luminescence intensity of the wavelength conversion member 1 can be further increased even when the thickness of the phosphor layer 3 is reduced. When the content A of the inorganic phosphor 5 in the phosphor layer 3 is equal to or less than the above upper limit, the thickness of the phosphor layer 3 does not need to be made too thin, and the proportion of the content of the inorganic matrix 4 in the phosphor layer 3 can be increased, so that the mechanical strength of the wavelength conversion member 1 can be further improved. When the content A of the inorganic phosphor 5 in the phosphor layer 3 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0039] In this embodiment, the thickness T of the phosphor layer 3 is preferably 2 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less.

[0040] When the thickness T of the phosphor layer 3 is equal to or greater than the above lower limit, the mechanical strength of the wavelength conversion member 1 can be further improved. When the thickness T of the phosphor layer 3 is equal to or less than the above upper limit, the luminous intensity of the wavelength conversion member 1 can be further increased. When the thickness T of the phosphor layer 3 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0041] The configuration of each layer of the wavelength conversion member 1 will be described in detail below.

[0042] Plate-shaped members; The shape of the plate-like member 2 is not particularly limited, and can be, for example, a substantially rectangular plate or a substantially circular plate. The thickness of the plate-like member 2 is not particularly limited, and can be, for example, 0.05 mm or more and 2 mm or less, preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, particularly preferably 0.5 mm or more, and preferably 1.5 mm or less, more preferably 1 mm or less, and even more preferably 0.75 mm or less. When the thickness of the plate-like member 2 is equal to or more than the lower limit, the mechanical strength can be further increased. When the thickness of the plate-like member 2 is equal to or less than the upper limit, the scattering and absorption of light in the plate-like member 2 can be further suppressed, and the emission efficiency of the fluorescence can be further increased.

[0043] Any light-transmitting material can be used for the plate-shaped member 2. Examples of materials for the plate-shaped member 2 include transparent materials and materials with a high haze value, regardless of whether they are colorless or colored.

[0044] The haze value of the plate-shaped member 2 is not particularly limited, and may be 1% or more, 5% or more, or 10% or more, and may be 70% or less, 60% or less, or 50% or less.

[0045] The plate-like member 2 is preferably transparent. The total light transmittance of the plate-like member 2 at a wavelength of 450 nm and a thickness of 1 mm is preferably 70% or more, more preferably 80% or more, even more preferably 82% or more, and particularly preferably 85% or more. The upper limit of the total light transmittance of the plate-like member 2 at a wavelength of 450 nm and a thickness of 1 mm is not particularly limited, but may be 95% or less, 93% or less, or 90% or less.

[0046] The linear transmittance of the plate-like member 2 at a wavelength of 450 nm and a thickness of 1 mm is not particularly limited, but is preferably 70% or more, more preferably 80% or more, even more preferably 82% or more, particularly preferably 85% or more, and is preferably 95% or less, more preferably 93% or less, and even more preferably 90% or less.

[0047] The material of the plate-shaped member 2 is not particularly limited, and may be, for example, a translucent ceramic. Examples of the translucent ceramic include oxide ceramics such as Al2O3, MgO, ZrO2, and Y2O3, and single crystal sapphire. Among them, from the viewpoint of further improving the heat resistance of the wavelength conversion member 1, the plate-shaped member 2 is preferably a sapphire substrate or a translucent alumina substrate.

[0048] The material of the plate-shaped member 2 may be glass. Examples of glass that can be used include borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, and tellurite glass. When the plate-shaped member 2 is a glass substrate, the adhesion to the inorganic matrix 4 can be further improved, particularly when the inorganic matrix 4 is a glass matrix.

[0049] Phosphor layer; The phosphor layer 3 includes an inorganic matrix 4 and an inorganic phosphor 5. The inorganic phosphor 5 is dispersed in the inorganic matrix 4.

[0050] The inorganic matrix 4 is not particularly limited as long as it can be used as a dispersion medium for the inorganic phosphor 5, and for example, a glass matrix can be used. As the glass matrix, for example, borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, tellurite glass, etc. can be used.

[0051] Examples of borosilicate glasses include those containing, by mass%, 30% to 85% SiO2, 30% to 30% Al2O, 30% to 50% B2O, 0% to 10% Li2O+Na2O+K2O, and 0% to 50% MgO+CaO+SrO+BaO. Examples of phosphate glasses include those containing, by molar%, 10% or more P2O5. Examples of tin phosphate glasses include those containing, by molar%, 30% to 90% SnO and 1% to 70% P2O5. Examples of bismuthate glasses include those containing, by mass%, 20% to 70% Bi2O3 and 20% to 70% B2O3. The tellurite-based glass may contain, in mole percent, 50% or more of TeO2, 0% to 45% of ZnO, 0% to 50% of RO (R is at least one selected from Ca, Sr, and Ba), and 0% to 50% of La2O3+Gd2O3+Y2O3.

[0052] The softening point of the glass matrix is ​​preferably from 250°C to 1000°C, more preferably from 300°C to 950°C, and further preferably from 500°C to 900°C.

[0053] If the softening point of the glass matrix is ​​too low, the mechanical strength and chemical durability of the wavelength conversion member 1 may decrease. In addition, since the heat resistance of the glass matrix itself is low, there is a risk of it softening and deforming due to the heat generated by the inorganic phosphor 5. On the other hand, if the softening point of the glass matrix is ​​too high, when a firing step is included in the manufacturing process, the inorganic phosphor 5 may deteriorate, and the luminescence intensity of the wavelength conversion member 1 may decrease.

[0054] From the viewpoint of further increasing the chemical stability and mechanical strength of the wavelength conversion member 1, the softening point of the glass matrix is ​​preferably 500° C. or higher, more preferably 600° C. or higher, even more preferably 700° C. or higher, particularly preferably 800° C. or higher, and most preferably 850° C. or higher. Examples of glasses constituting such a glass matrix include borosilicate glasses.

[0055] However, when the softening point of the glass matrix increases, the firing temperature also increases, and as a result, the manufacturing cost tends to increase. Also, when the heat resistance of the inorganic phosphor 5 is low, there is a risk of deterioration due to firing. Therefore, when manufacturing the wavelength conversion member 1 at a lower cost or when the heat resistance of the inorganic phosphor 5 is lower, the softening point of the glass matrix is preferably 550 °C or lower, more preferably 530 °C or lower, still more preferably 500 °C or lower, particularly preferably 480 °C or lower, and most preferably 460 °C or lower. Examples of the glass constituting such a glass matrix include tin phosphate glass, bismuthate glass, and tellurite glass.

[0056] Note that the inorganic matrix 4 may be a ceramic matrix. When the inorganic matrix 4 is a ceramic matrix, the heat resistance of the wavelength conversion member 1 can be further improved. Examples of the ceramic constituting the ceramic matrix include, for example, Al2O3, MgO, AlN, etc.

[0057] The inorganic phosphor 5 is not particularly limited as long as it emits fluorescence upon incidence of excitation light. Examples of the inorganic phosphor 5 include oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, oxychloride phosphors, sulfide phosphors, oxysulfide phosphors, halide phosphors, chalcogenide phosphors, aluminate phosphors, halophosphate chloride phosphors, or garnet-based compound phosphors, etc. These phosphors may be used alone or in combination of multiple types. When blue light is used as the excitation light, for example, a phosphor that emits yellow light as fluorescence can be used. Examples of the phosphor that emits yellow light as fluorescence include, for example, (Y,Gd)3(Al,Ga)5O 12 :Ce (YAG phosphor), Lu3Al5O 12 :Ce, La3Si6N 11 :Ce, Si 6-z Al z O z N 8-z :Eu(0 < z < 4.2) (β-SiAlON:Eu), Ca-α-sialon:Eu, or Li2SrSiO4:Eu, etc.

[0058] The density of the inorganic phosphor 5 is not particularly limited and is preferably 3.0 g / cm 3 or more than 3.5g / cm 3 or more, and 3 or less than 5.5g / cm 3 When the density of the inorganic phosphor 5 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0059] The BET specific surface area of ​​the inorganic phosphor 5 is not particularly limited, and is preferably 0.01 m 2 / g or more, more preferably 0.05m 2 / g or more, more preferably 0.1m 2 / g or more, preferably 10m 2 / g or less, more preferably 5m 2 / g or less, more preferably 2m 2 / g or less. When the BET specific surface area of ​​inorganic phosphor 5 is within the above range, the light extraction efficiency of wavelength conversion member 1 can be more effectively improved. The BET specific surface area of ​​inorganic phosphor 5 can be measured by a multipoint BET method using nitrogen as the adsorbate.

[0060] An example of a method for manufacturing the wavelength conversion member 1 will now be described.

[0061] Manufacturing method; In the method for manufacturing the wavelength conversion member 1, first, the plate-shaped member 2 is prepared. As the plate-shaped member 2, the above-mentioned one can be used. In addition, a paste for forming a phosphor layer is prepared separately. The paste for forming a phosphor layer is prepared as a paste containing inorganic particles that will become the inorganic matrix 4 and inorganic phosphor particles that will become the inorganic phosphor 5. The paste for forming a phosphor layer may contain a solvent and a binder resin.

[0062] Next, the prepared phosphor layer forming paste is applied onto the first main surface 2a of the plate-shaped member 2. Examples of the application method include a method of applying with a coater, a doctor blade method, and the like. Next, the phosphor layer forming paste is fired. Thereby, the phosphor layer 3 is formed on the first main surface 2a of the plate-shaped member 2, and the wavelength conversion member 1 can be obtained.

[0063] In addition, when firing the phosphor layer forming paste, it is preferable to previously dry the phosphor layer forming paste and then fire it.

[0064] The firing temperature of the phosphor layer forming paste is not particularly limited, but for example, when the inorganic particles constitute the glass powder, it is preferably equal to or higher than the softening point of the glass powder, and more preferably higher than the softening point of the glass powder. The firing temperature of the phosphor layer forming paste is preferably equal to or lower than the softening point of the glass powder +150°C, more preferably equal to or lower than the softening point of the glass powder +120°C, even more preferably equal to or lower than the softening point of the glass powder +100°C, even more preferably equal to or lower than the softening point of the glass powder +50°C, and particularly preferably lower than the softening point of the glass powder +50°C. Even if the firing temperature is equal to or higher than the softening point of the glass powder +100°C, the phosphor layer forming paste can be fired within a range in which the plate-like member 2 does not deform. The firing time at the above firing temperature can be, for example, 10 minutes or more and 100 minutes or less. The firing atmosphere of the phosphor layer forming paste is preferably a reduced pressure atmosphere, and more preferably a vacuum atmosphere. The phosphor layer forming paste can be fired in air or in a nitrogen atmosphere.

[0065] In the method for producing the wavelength conversion member 1, in the step of forming the phosphor layer 3, the average particle diameter of the inorganic phosphor 5 (inorganic phosphor particles) is set to D 50 (μm), the content of the inorganic phosphor 5 in the phosphor layer 3 is A (volume %), and the thickness of the phosphor layer 3 is T (μm). The parameter P expressed by the above formula (1) is set to 2 or more and 12 or less. 50(μm), the above A (volume %), and the above T (μm). Thereby, in the method for producing wavelength conversion member 1, the light extraction efficiency of the obtained wavelength conversion member 1 can be effectively increased.

[0066] Second embodiment Fig. 3 is a schematic cross-sectional view showing a wavelength conversion member according to a second embodiment of the present invention. As shown in Fig. 3, in a wavelength conversion member 21, a bandpass filter 22 is provided on a first main surface 2a of a plate-shaped member 2. The bandpass filter 22 is provided between the first main surface 2a of the plate-shaped member 2 and the phosphor layer 3.

[0067] As the bandpass filter 22, for example, a filter that transmits the excitation light X and reflects the fluorescence can be used. By providing such a bandpass filter 22 between the first main surface 2a of the plate-shaped member 2 and the phosphor layer 3, the excitation light X can be transmitted more efficiently and the amount of fluorescent components that become return light can be reduced, so that the light extraction efficiency of the wavelength conversion member 21 can be further improved.

[0068] The bandpass filter 22 may be, for example, a dielectric multilayer film. The dielectric multilayer film may be a multilayer film having a configuration in which low-refractive index dielectric layers with a relatively low refractive index and high-refractive index dielectric layers with a relatively high refractive index are alternately stacked. The low-refractive index dielectric layers may be formed of, for example, silicon oxide. The high-refractive index dielectric layers may be formed of, for example, titanium oxide, niobium oxide, lanthanum oxide, tantalum oxide, zirconium oxide, etc.

[0069] The thickness of the bandpass filter 22 is not particularly limited, and is preferably 500 nm or more, more preferably 1000 nm or more, further preferably 2000 nm or more, and is preferably 10000 nm or less, more preferably 9000 nm or less, and further preferably 8000 nm or less. If the thickness of the bandpass filter 22 is too small, a sufficient filter function may not be obtained. In addition, the mechanical strength of the bandpass filter 22 tends to be insufficient. On the other hand, if the thickness of the bandpass filter 22 is too large, the stress generated in the bandpass filter 22 itself becomes large, and there is a risk that the bandpass filter 22 may crack or peel off from the plate-like member 2 or the like.

[0070] The other points are similar to those of the first embodiment.

[0071] In the wavelength conversion member 21 of the present embodiment, the average particle diameter of the inorganic phosphor 5 in the phosphor layer 3 is also set to D 50 (μm), the content of inorganic phosphor 5 in phosphor layer 3 is A (volume %), and the thickness of phosphor layer 3 is T (μm). Since parameter P represented by the above formula (1) is 2 or more and 12 or less, the light extraction efficiency of wavelength conversion member 21 can be effectively increased.

[0072] In this embodiment, the bandpass filter 22 is provided between the first main surface 2a of the plate-shaped member 2 and the phosphor layer 3, but the bandpass filter 22 may be provided, for example, on the second main surface 2b of the plate-shaped member 2, and the position at which the bandpass filter 22 is provided is not particularly limited. The bandpass filter 22 may be provided both between the first main surface 2a of the plate-shaped member 2 and the phosphor layer 3, and on the second main surface 2b of the plate-shaped member 2.

[0073] Moreover, other functional films such as an anti-reflection film may be provided instead of the band-pass filter 22. The other functional films such as an anti-reflection film may also be provided between the first main surface 2a of the plate-shaped member 2 and the phosphor layer 3, or may be provided on the second main surface 2b of the plate-shaped member 2.

[0074] For example, when the plate-shaped member 2 is a sapphire substrate or the like, it is preferable to provide an anti-reflection film on the second main surface 2b of the plate-shaped member 2. This allows the excitation light X to be more efficiently incident on the plate-shaped member 2 even when the plate-shaped member 2 is a substrate with a high refractive index such as a sapphire substrate, and allows the light extraction efficiency of the wavelength conversion member 21 to be more effectively increased.

[0075] The anti-reflection film may be a low refractive index film or a dielectric multilayer film. As the dielectric multilayer film, a multilayer film having a configuration in which a low refractive index dielectric layer having a relatively low refractive index and a high refractive index dielectric layer having a relatively high refractive index are alternately laminated can be used.

[0076] Although not shown, the phosphor layer 3 constituting the wavelength conversion member 1 may be provided in a plurality of layers. In this case, the inorganic phosphor 5 contained in each phosphor layer 3 may be the same type of phosphor or different types of phosphors.

[0077] [Light Emitting Device] Fig. 4 is a schematic cross-sectional view showing a light-emitting device according to one embodiment of the present invention. As shown in Fig. 4, the light-emitting device 11 includes the wavelength conversion member 1 according to the first embodiment described above, and a light source 10 that emits excitation light X to the wavelength conversion member 1. In the light-emitting device 11, the light source 10 is disposed so that the excitation light X is directly incident on the wavelength conversion member 1 from the plate-shaped member 2 side.

[0078] Since the light emitting device 11 includes the above-mentioned wavelength conversion member 1, the light extraction efficiency from the wavelength conversion member 1 can be increased, and thus the emission intensity can be increased.

[0079] The arrangement of the light source 10 is not limited to the embodiment shown in FIG. 4. For example, in a modified example shown in FIG. 5, a light guide plate 12 is arranged between the light source 10 and the wavelength conversion member 1. The light source 10 is arranged so that the excitation light X is directly incident on the light guide plate 12. The excitation light X emitted from the light source 10 passes through the light guide plate 12 and enters the wavelength conversion member 1. Specifically, the excitation light X enters the end face of the light guide plate 12, exits from the main surface of the light guide plate 12, and enters the wavelength conversion member 1. Here, the light guide plate 12 uses a material that absorbs the excitation light X as little as possible. In addition, the light guide plate 12 and the wavelength conversion member 1 may be joined together.

[0080] The present invention will be described in more detail below with reference to specific examples. The present invention is not limited to the following examples, and can be modified as appropriate within the scope of the present invention.

[0081] As a plate-like member, a 25 mm square glass substrate (thickness: 0.5 mm, total light transmittance at a wavelength of 450 nm and a thickness of 1 mm: 90%) was prepared.

[0082] The glass matrix material that constitutes the phosphor layer is borosilicate glass powder (average particle diameter D 50 : 3 μm) was prepared.

[0083] In addition, YAG phosphor powder was prepared as an inorganic phosphor material for forming the phosphor layer. As the YAG phosphor powder, inorganic phosphor a and inorganic phosphor b shown in Table 1 below were prepared.

[0084] [Table 1]

[0085] The average particle diameter D of each inorganic phosphor is 50 was measured using a laser diffraction particle size distribution analyzer (Shimadzu Corporation, model number "SALD-7500").

[0086] The BET specific surface area of ​​each inorganic phosphor was measured using a fully automatic specific surface area measuring device (Mountec Co., Ltd., product number "HM model-1201").

[0087] Example 1 The borosilicate glass powder and the vehicle were mixed and then kneaded uniformly in a three-roll mill to obtain a glass powder paste. The vehicle used was a solution of ethyl cellulose in α-terpineol, and the mass ratio of glass powder to vehicle was adjusted to 2 to 3.

[0088] After mixing the inorganic phosphor a and the vehicle, the mixture was kneaded uniformly in a three-roll mill to obtain a YAG phosphor powder paste. Note that the vehicle used was a solution of ethyl cellulose in α-terpineol, and the mass ratio of inorganic phosphor a / vehicle was adjusted to 2-3.

[0089] The obtained glass powder paste and YAG phosphor powder paste were adjusted to a volume ratio of 4:6, and then kneaded in a planetary centrifugal mixer. Next, the mixture was uniformly kneaded in a three-roll mill to obtain a composite powder paste of glass powder and YAG phosphor powder (composite powder / vehicle mass ratio of 2 to 3).

[0090] Next, a metal mask was set on the main surface of a 25 mm square plate-like member (glass substrate), and the obtained composite powder paste was applied to a predetermined location by pressing and moving a squeegee. Next, the applied composite powder paste was dried at 150°C for 20 minutes, and then placed in an electric furnace and fired at a peak temperature of 850°C for 30 minutes, and naturally cooled to room temperature, thereby sintering a phosphor layer on the main surface of the plate-like member. In this way, a wavelength conversion member was obtained in which a phosphor layer was provided on the main surface of the plate-like member. The obtained wavelength conversion member was cut into small pieces of 5 mm for use.

[0091] In the phosphor layer formed in Example 1, the average particle diameter of the inorganic phosphor a is D 50The value of parameter P was calculated using the following formula (1), where A (volume %) is the content of inorganic phosphor a in the phosphor layer, and T (µm) is the thickness of the phosphor layer. In formula (1), the content A of inorganic phosphor a is multiplied by the volume ratio of the content of inorganic phosphor a to the entire material in the phosphor layer.

[0092] P = (1 / (D 50 ) 0.5 )×A×T…Formula (1)

[0093] Furthermore, the obtained wavelength conversion member was evaluated for its fluorescence peak intensity when irradiated with blue LD using an industrial camera (Basler). The results are shown in Table 2 below.

[0094] (Examples 2 to 4 and Comparative Examples 1 and 2) A wavelength conversion member was obtained in the same manner as in Example 1, except that metal masks of different thicknesses were prepared and the thickness of the phosphor layer was set as shown in the following Table 2. Furthermore, the value of parameter P represented by the above formula (1) and the fluorescence peak intensity were determined in the same manner as in Example 1. The results are shown in Table 2 below.

[0095] [Table 2]

[0096] Fig. 6 is a graph showing the relationship between the value of parameter P and the fluorescence peak intensity in Examples 1 to 4 and Comparative Examples 1 and 2. As shown in Fig. 6, it can be seen that when the value of parameter P is 2 or more and 12 or less, the fluorescence peak intensity is effectively increased.

[0097] (Examples 5 to 8 and Comparative Example 3) A wavelength conversion member was obtained in the same manner as in Example 1, except that inorganic phosphor b shown in Table 1 above was used as the inorganic phosphor, and the thickness of the phosphor layer was set as shown in Table 3 below. The value of parameter P and the fluorescence peak intensity were determined in the same manner as in Example 1. The results are shown in Table 3 below.

[0098] [Table 3]

[0099] Fig. 7 is a graph showing the relationship between the value of parameter P and the fluorescence peak intensity in Examples 5 to 8 and Comparative Example 3. As shown in Fig. 7, it can be seen that when the value of parameter P is 2 or more and 12 or less, the fluorescence peak intensity is effectively increased. [Explanation of symbols]

[0100] 1, 21...Wavelength conversion material 2...Plate-shaped member 2a…First main surface 2b…Second main surface 3...Phosphor layer 4…Inorganic matrix 5...Inorganic phosphor 10…Light source 11...Light emitting device 12...Light guide plate 22...Bandpass filter X: Excitation light Y…Synthetic light

Claims

1. A plate-like member; A phosphor layer provided on a main surface of the plate-shaped member; Equipped with the phosphor layer includes an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix; The average particle diameter of the inorganic phosphor is D ５０ a parameter P represented by the following formula (1) is 2 or more and 12 or less, where A is the volume percent of the inorganic phosphor in the phosphor layer, A is the volume percent of the inorganic phosphor in the phosphor layer, and T is the thickness of the phosphor layer: P = (1 / (D ５０ ) ０．５ )×A×T …Formula (1)

2. The average particle diameter D of the inorganic phosphor ５０ The wavelength conversion member according to claim 1 , wherein the thickness of the first insulating film is 1 μm or more and 30 μm or less.

3. The wavelength conversion member according to claim 1 , wherein a content A of the inorganic phosphor in the phosphor layer is 20% by volume or more and 80% by volume or less.

4. The wavelength conversion member according to claim 1 , wherein the phosphor layer has a thickness T of 2 μm or more and 300 μm or less.

5. The wavelength conversion member according to claim 1 , wherein the inorganic matrix is ​​a glass matrix.

6. 3. The wavelength conversion member according to claim 1, wherein the plate-shaped member has a total light transmittance of 70% or more and 95% or less at a wavelength of 450 nm and a thickness of 1 mm.

7. 3. The wavelength conversion member according to claim 1, wherein the plate-like member is at least one substrate selected from the group consisting of a glass substrate, a sapphire substrate, and a translucent alumina substrate.

8. The wavelength conversion member according to claim 1 , wherein the plate-like member has a thickness of 0.05 mm or more and 2 mm or less.

9. the plate-like member has a first main surface and a second main surface opposed to each other; The phosphor layer is provided on the first main surface side of the plate-shaped member, The wavelength conversion member according to claim 1 , further comprising a bandpass filter provided between the first main surface of the plate-shaped member and the phosphor layer, or on the second main surface of the plate-shaped member.

10. The wavelength conversion member according to claim 1 or 2, A light source that emits excitation light to the wavelength conversion member; A light emitting device comprising:

11. preparing a plate-like member; forming a phosphor layer on a main surface of the plate-like member, the phosphor layer including an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix; Equipped with In the step of forming the phosphor layer, the average particle diameter of the inorganic phosphor is set to D ５０ (μm), the content of the inorganic phosphor in the phosphor layer is A (volume %), and the thickness of the phosphor layer is T (μm). The parameter P represented by the following formula (1) is set to be 2 or more and 12 or less. ５０ (μm), the A (volume %), and the T (μm). P = (1 / (D ５０ ) ０．５ )×A×T …Formula (1)

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