Wavelength conversion member and method for producing same, light emitting device, and projector

Abstract

To provide a wavelength conversion member capable of constituting a light-emitting device having higher light emission efficiency, and a method of manufacturing the same.SOLUTION: There is provided a wavelength conversion member which comprises a substrate and a wavelength conversion layer arranged on the substrate and including a binding material and a fluorescent body. The wavelength conversion layer has a volume ratio of 0.75 to 1.45 of the fluorescent body to the binding material and also has a mean thickness of 55 to 146 μm. A method of manufacturing the wavelength conversion member includes: imparting a fluorescent body composition onto the substrate, wherein the fluorescent body composition includes the binding material, a solvent and the fluorescent body, the solvent has a boiling point of 200 to 300°C, and the fluorescent body composition has a mass ratio of 0.01 to 0.4 of the solvent to the binding material and a mass ratio of 3.15 to 6.05 of the fluorescent body to the binding material; and thermally treating the fluorescent body composition imparted onto the substrate to form the wavelength conversion layer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a wavelength conversion member and a manufacturing method thereof, a light emitting device, and a projector. [Background technology]

[0002] In an image projection device (projector) that displays a color image by projecting light emitted from a light emitting device onto a screen using a micromirror display element or the like, there is a demand for a light emitting device with a high output. For example, Patent Document 1 proposes a light emitting device equipped with a wavelength conversion element that has a higher conversion efficiency from excitation light to fluorescence. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 198949 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one aspect of the present disclosure is to provide a wavelength conversion member capable of forming a light emitting device with higher light emitting efficiency, a manufacturing method thereof, a light emitting device, and a projector. [Means for solving the problem]

[0005] A first aspect is a wavelength conversion member comprising a substrate and a wavelength conversion layer disposed on the substrate and containing a binder and a phosphor, the wavelength conversion layer having a volume ratio of the phosphor to the binder of 0.75 to 1.45 and an average thickness of 55 μm to 146 μm.

[0006] A second aspect is a wavelength conversion member comprising a substrate and a wavelength conversion layer disposed on the substrate and containing a binder and a phosphor, the wavelength conversion layer having a ratio of the sum of the particle cross-sectional areas of the phosphor particles to the cross-sectional area of ​​the wavelength conversion layer in a cross section perpendicular to the surface on which the wavelength conversion layer is disposed on the substrate of 56% to 70%, and an average thickness of 55 μm to 146 μm.

[0007] A third aspect is a light emitting device including the wavelength conversion member of the first or second aspect, a motor that rotates the wavelength conversion member, and a light source that irradiates the wavelength conversion member with light. A fourth aspect is a projector including the light emitting device of the third aspect, an image display system, and a projection optical system.

[0008] A fifth aspect is a method for producing a wavelength conversion member, comprising: applying onto a substrate a phosphor composition comprising a binder, a solvent, and a phosphor, wherein the boiling point of the solvent is 200°C or more and 300°C or less, the mass ratio of the solvent to the binder is 0.01 or more and 0.4 or less, and the mass ratio of the phosphor to the binder is 3.15 or more and 6.05 or less; and heat-treating the phosphor composition applied onto the substrate to form a wavelength conversion layer. Effect of the Invention

[0009] According to one aspect of the present disclosure, it is possible to provide a wavelength conversion member capable of forming a light emitting device with higher light emitting efficiency, a method for manufacturing the same, a light emitting device, and a projector. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a light emitting device. [Diagram 2] FIG. 1 is a schematic diagram illustrating an example of the configuration of a projector. [Diagram 3] FIG. 1A is a schematic cross-sectional view showing an example of the configuration of a wavelength conversion member, FIG. 1B is a schematic perspective view showing an example of the configuration of a wavelength conversion member, and FIG. 1C is a schematic plan view showing an example of the configuration of a wavelength conversion member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In this specification, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In addition, the content of each component in a composition means the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition. Furthermore, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. In this specification, in a formula representing the composition of a phosphor or luminescent material, multiple elements separated by a comma (,) mean that at least one of these multiple elements is contained in the composition. In addition, in a formula representing the composition of a phosphor, the part before the colon (:) represents the host crystal, and the part after the colon (:) represents the activator element. In this specification, the relationship between the color name and the chromaticity coordinate, the relationship between the wavelength range of light and the color name of monochromatic light, etc., are in accordance with JIS Z8110. The half width of a phosphor means the wavelength width (full width at half maximum; FWHM) of the emission spectrum where the emission intensity is 50% of the maximum emission intensity in the emission spectrum of the phosphor. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments described below are examples of a wavelength conversion member and a manufacturing method thereof, a light emitting device, and a projector for embodying the technical concept of the present invention, and the present invention is not limited to the wavelength conversion member and a manufacturing method thereof, a light emitting device, and a projector described below.

[0012] Wavelength conversion material A wavelength conversion member according to a first aspect includes a substrate and a wavelength conversion layer disposed on the substrate, the wavelength conversion layer having a volume ratio of the phosphor to the binder of 0.75 to 1.45 and an average thickness of 55 μm to 146 μm.

[0013] The luminous efficiency of a light emitting device consisting of a light source, a wavelength conversion member, and an optical system including, for example, a lens and a reflector is evaluated by the total efficiency, which is the product of the fluorescent efficiency in the wavelength conversion member and the light collection efficiency in the optical system. In other words, the total efficiency of a light emitting device means the luminous efficiency of the entire light emitting device. The fluorescent efficiency corresponds to the wavelength conversion efficiency of the wavelength conversion member, and is evaluated as the ratio of the intensity of the emitted light from the wavelength conversion layer to the intensity of the incident light from the light source. The light collection efficiency corresponds to the efficiency with which the emitted light from the wavelength conversion member is taken into the optical system, and is evaluated as the ratio of the intensity of the light output from the optical system to the intensity of the emitted light from the wavelength conversion layer.

[0014] A wavelength conversion member in which a wavelength conversion layer having a volume ratio of phosphor to binder contained in the wavelength conversion layer of 0.75 to 1.45 and an average thickness of 55 μm to 146 μm is disposed on a substrate can achieve higher fluorescence efficiency when combined with a light source to form a light emitting device. This can be considered as follows, for example. Since the volume ratio of phosphor contained in the wavelength conversion layer is high, the fluorescence efficiency in the wavelength conversion layer is high, and the spread of light extracted from the wavelength conversion layer is suppressed, resulting in high light collection efficiency, and the total efficiency of the light emitting device is improved. Furthermore, since the thickness of the wavelength conversion layer is within a predetermined range, the spread of light is suppressed and the light collection efficiency is high, the heat dissipation of the wavelength conversion layer is improved, and the rise in surface temperature is suppressed, resulting in high fluorescence efficiency. It is believed that the high fluorescence efficiency and light collection efficiency in this way improve the total efficiency of the light emitting device.

[0015] A wavelength conversion member of a second aspect includes a substrate and a wavelength conversion layer disposed on the substrate and containing a binder and a phosphor, the wavelength conversion layer having a ratio of the sum of the cross-sectional areas of phosphor particles in a cross section perpendicular to the surface on which the wavelength conversion layer is disposed on the substrate to a cross-sectional area of ​​the wavelength conversion layer of 56% to 70% and an average thickness of 55 μm to 146 μm.

[0016] A wavelength conversion member in which a wavelength conversion layer having a ratio of the total particle cross-sectional area of ​​the phosphor to the cross-sectional area of ​​the wavelength conversion layer in the cross section is 56% to 70% and an average thickness of 55 μm to 146 μm is arranged on a substrate can achieve higher fluorescence efficiency when combined with a light source to form a light emitting device. This can be considered as follows, for example. Since the volume ratio of the phosphor contained in the wavelength conversion layer is high, the fluorescence efficiency in the wavelength conversion layer is high, and the spread of the light extracted from the wavelength conversion layer is suppressed, resulting in high light collection efficiency, and the total efficiency of the light emitting device is improved. Furthermore, since the thickness of the wavelength conversion layer is within a predetermined range, the spread of light is suppressed and the light collection efficiency is increased, the heat dissipation of the wavelength conversion layer is improved, and the rise in surface temperature is suppressed, resulting in high fluorescence efficiency. It is believed that the total efficiency of the light emitting device is improved by increasing the fluorescence efficiency and light collection efficiency in this way.

[0017] Here, the evaluation method of the fluorescence efficiency and the light collection efficiency will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a light emitting device. The light emitting device 200 includes a light source 210, a lens 222 that collects light from the light source 210 on a wavelength conversion member 250, and a dichroic mirror 224 that reflects the output light from the wavelength conversion member 250 and directs the direction of the output light toward the lens system 230. The wavelength conversion member 250 includes a disk-shaped substrate 252 and a wavelength conversion layer 254 that includes a phosphor and a binder. The wavelength conversion layer 254 is disposed, for example, in an annular shape along the circumference of the substrate 252. The fluorescence efficiency of the light emitting device 200 is calculated by dividing the fluorescence output measured by a power meter at position B by the excitation output measured by a power meter at position A. The light collection efficiency is calculated by dividing the emission output measured by a power meter at position C by the fluorescence output measured by a power meter at position B. The total efficiency of the light emitting device 200 is calculated as the product of the fluorescence efficiency and the light collection efficiency, and corresponds to the value obtained by dividing the emission power by the excitation power. In addition, in evaluating the fluorescence efficiency, the surface temperature of the wavelength conversion layer 254 may be measured by infrared thermography to confirm that an increase in the surface temperature is suppressed.

[0018] The wavelength conversion member includes a substrate and a wavelength conversion layer disposed on the substrate. An example of the configuration of the wavelength conversion member will now be described with reference to the drawings. FIG. 3(a) is a schematic cross-sectional view showing an example of the configuration of the wavelength conversion member, FIG. 3(b) is a schematic perspective view showing an example of the configuration of the wavelength conversion member, and FIG. 3(c) is a schematic plan view showing an example of the configuration of the wavelength conversion member. The wavelength conversion member 10 has a phosphor layer 14 formed on a substrate 12. In FIG. 3, the substrate 12 has a disk-like shape. The phosphor layer 14 is arranged in an annular shape along the circumference of the substrate 12. The wavelength conversion member 10 absorbs excitation light irradiated from a light source, generates converted light having a wavelength different from that of the excitation light, and emits the converted light. The wavelength conversion member 10 may, for example, absorb blue light from a light source, emit converted light having a wavelength different from that of the blue light converted by the phosphor layer 14, and reflect the blue light to emit a mixed color light of the converted light and the blue light, or may emit only the converted light. The wavelength conversion member can convert the excitation light from the light source into light of various colors.

[0019] The substrate constituting the wavelength conversion member is not limited to a disk shape, and may have a shape such as a polygonal plate, etc. The thickness of the substrate may be, for example, 0.1 mm or more and 1 mm or less, and preferably 0.4 mm or more or 0.6 mm or less.

[0020] The substrate may be a metal member containing a metal material such as aluminum, iron, copper, silver, nickel, stainless steel, etc. When the substrate is a metal member containing a metal material, the light incident on the wavelength conversion member can be wavelength-converted by the wavelength conversion layer and reflected to the same side as the incident surface. Furthermore, the heat dissipation from the phosphor is improved, so that the fluorescent efficiency of the wavelength conversion member can be increased.

[0021] The substrate may be a light-transmitting member containing a light-transmitting material such as glass or aluminum oxide. When the substrate is a light-transmitting member, the light incident on the wavelength conversion member can be wavelength-converted by the wavelength conversion layer and emitted to the opposite side of the incident surface. At least one of the main surface of the light-transmitting member on which the wavelength conversion layer is formed and the other main surface opposite thereto may be roughened in advance by, for example, etching or laser processing. This can suppress uneven light emission on the light-emitting surface of the wavelength conversion member.

[0022] At least a part of the surface of the substrate may be a reflective surface. The reflective surface may be formed at least in the region where the wavelength conversion layer is disposed. The reflective surface may be formed from a material containing at least one selected from the group consisting of silver and aluminum. The reflective surface of the substrate may be formed from the material of the substrate itself. That is, the substrate itself may be formed from a material containing at least one selected from the group consisting of silver and aluminum, and at least a part of the surface may be a reflective surface. Alternatively, the reflective surface may be formed by the surface of a reflective layer disposed on the substrate. Examples of materials for forming the reflective layer include silver, aluminum, alloys containing at least one selected from the group consisting of silver and aluminum, and resins containing metal oxides such as titanium oxide. The regular reflectance of the reflective surface may be, for example, 80% or more, and preferably 85% or more, or 90% or more. The upper limit of the regular reflectance may be, for example, 100% or less. When the regular reflectance of the reflective surface is 80% or more, there is a tendency that the amount of light extracted can be increased. The regular reflectance of the reflective surface of the substrate is measured using light having a wavelength of 450 nm.

[0023] The wavelength conversion layer disposed on the substrate may include a binder and a phosphor. The binder constituting the wavelength conversion layer may be an organic binder or an inorganic binder. The organic binder may include a cured product of a resin, preferably a cured product of a light-transmitting resin. Examples of the resin include thermosetting resins such as epoxy resin, silicone resin, epoxy-modified silicone resin, and modified silicone resin. When the resin includes a silicone resin, the resin tends to have better heat resistance, light resistance, and the like. The silicone resin or modified silicone resin may include at least one selected from the group consisting of a phenyl silicone resin, a modified phenyl silicone resin, a dialkyl silicone resin, and a modified dialkyl silicone resin. Examples of the inorganic binder include glass, ceramics, and aluminum oxide.

[0024] The content of the binder in the wavelength converting layer may be, for example, 10% by mass or more and 25% by mass or less, preferably 12% by mass or more or 14% by mass or more, and preferably less than 25% by mass, 23% by mass or less, or 20% by mass or less, relative to the total mass of the wavelength converting layer.

[0025] The phosphor constituting the wavelength conversion layer may include at least one kind of rare earth aluminate phosphor, for example. The rare earth aluminate phosphor may have a composition including at least one first element selected from the group consisting of yttrium, lanthanum, lutetium, gadolinium, and terbium, at least one second element selected from the group consisting of aluminum, gallium, and scandium, and including at least aluminum, and cerium. The composition of the rare earth aluminate phosphor may have a molar content ratio of the first element, for example, when the total number of moles of the second element is 5 moles, from 2.5 to 3.5, and preferably from 2.8 to 3.2. In addition, when the total number of moles of the second element is 5 moles, the molar content ratio of oxygen atoms may be, for example, from 10 to 14, and preferably from 11 to 13. In addition, the molar content ratio of aluminum to the total number of moles of the second element may be, for example, more than 0 and less than 1, and preferably from 0.4 to 1.0. The second element in the composition of the rare earth aluminate phosphor may be partially substituted with at least one element selected from the group consisting of silicon and germanium. The rare earth aluminate phosphor may have a theoretical composition represented by the following formula (1), for example.

[0026] (Y,Lu,Gd)3(Ga,Al)5O 12 :Ce (1)

[0027] The rare earth aluminate phosphor may have a composition different from the theoretical composition as long as it has the same luminescence characteristics as the theoretical composition represented by formula (1). For example, the rare earth aluminate phosphor may have a composition represented by the following formula (1a).

[0028] (Y, Lu, Gd) i (Ga,Al)O j :Ce (1a)

[0029] In formula (1a), i and j may satisfy 2.5≦i≦3.5 and 10≦j≦14, and preferably satisfy 2.8≦i≦3.2 and 11≦j≦13.

[0030] The emission peak wavelength of the rare earth aluminate phosphor may be, for example, 450 nm or more and 580 nm or less, and preferably 490 nm or more, 500 nm or more, 520 nm or more, or 550 nm or more. The upper limit of the emission peak wavelength may be, for example, 575 nm or less, 570 nm or less, or 560 nm or less. The half width may be, for example, 80 nm or more and 150 nm or less, and preferably 90 nm or more, 100 nm or more, or 110 nm or more, and preferably 140 nm or less, 130 nm or less, or 125 nm or less.

[0031] The central particle size of the phosphor may be, for example, 15 μm or more and 40 μm or less, preferably 17 μm or more, 20 μm or more, 22 μm or more, or 24 μm or more, and preferably 35 μm or less, 33 μm or less, or 31 μm or less. When the central particle size of the phosphor is within the above range, a wavelength conversion member with higher fluorescence efficiency tends to be obtained. The central particle size of the phosphor means the volume average particle size (median diameter), and is the particle size corresponding to 50% of the volume cumulative frequency from the small diameter side in the volume cumulative particle size distribution. The volume average particle size is measured, for example, using a laser diffraction type particle size distribution measuring device.

[0032] The particle size distribution of the phosphor may be, for example, a single-peak particle size distribution from the viewpoint of improving luminance, and preferably a single-peak particle size distribution with a narrow distribution width. Specifically, in the volume-based particle size distribution, the particle size corresponding to 10% of the volume cumulative from the small diameter side is defined as D 10 , the particle size corresponding to 90% of the cumulative volume is D 90 Then, D 10 D 90 Ratio of (D 90 / D 10 ) may be, for example, 3.0 or less.

[0033] The density of the phosphor is, for example, 4 g / cm 3 More than 7g / cm 3 or less, preferably 4.5 g / cm 3 or more, and preferably 6.9 g / cm3 Below, 6g / cm 3 or less than 5g / cm 3 It may be the following:

[0034] The wavelength conversion layer may further contain other components in addition to the phosphor and the binder. Examples of the other components include fillers such as silica, barium titanate, titanium oxide, and aluminum oxide, light stabilizers, and colorants. When the wavelength conversion member contains other components, the content of the other components can be appropriately selected depending on the purpose. For example, when the other components include a filler, the content of the filler can be 0.01 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder.

[0035] The mass ratio of the phosphor to the binder in the wavelength conversion layer may be, for example, 3.15 or more and 6.05 or less, preferably 3.5 or more, 3.8 or more, or 4 or more, and preferably 6 or less.

[0036] The volume ratio of the phosphor to the binder contained in the wavelength conversion layer may be, for example, 0.75 or more and 1.45 or less, preferably 0.8 or more, 0.84 or more, 0.88 or more, 0.94 or more, or 0.96 or more, and preferably 1.44 or less, 1.43 or less, 1.2 or less, or 1.0 or less. When the volume ratio of the phosphor to the binder is within the above range, the total efficiency of the light emitting device tends to be further improved. Here, the volume ratio of the phosphor to the binder contained in the wavelength conversion layer is calculated by dividing the area occupied by the phosphor by the area occupied by the resin in any cross section of the wavelength conversion layer. Here, the area occupied by the resin is calculated, for example, by subtracting the area occupied by the phosphor from the area of ​​the wavelength conversion layer. In addition, any cross section of the wavelength conversion layer may be a cross section that intersects with the substrate on which the wavelength conversion layer is disposed.

[0037] The volume ratio of the phosphor to the binder contained in the wavelength conversion layer may be approximately calculated as the ratio of the volume of the phosphor to the volume of the binder contained in the phosphor composition forming the wavelength conversion layer. Here, the volume of the binder is calculated by dividing the mass of the binder contained in the phosphor composition by the density of the binder. Also, the volume of the phosphor is calculated by dividing the mass of the phosphor contained in the phosphor composition by the density of the phosphor.

[0038] In a cross section perpendicular to the surface where the wavelength conversion layer is placed on the substrate, the ratio of the sum of the cross-sectional areas of the phosphor particles to the cross-sectional area of ​​the wavelength conversion layer (hereinafter also referred to as the "cross-sectional ratio") may be, for example, 56% or more and 70% or less. The cross-sectional ratio may be preferably 58% or more, 60% or more, 61% or more, or 62% or more. The cross-sectional ratio may also be 68% or less, 66% or less, 65% or less, or 64% or less. When the cross-sectional ratio is within the above range, the luminous intensity of the output light tends to be further improved. Here, the sum of the cross-sectional areas of the phosphor particles is the sum of the cross-sectional areas of the individual phosphor particles observed in the cross section of the wavelength conversion layer.

[0039] The cross-sectional ratio is calculated, for example, as follows. In the cross section of the wavelength conversion layer perpendicular to the main surface of the substrate on which the wavelength conversion layer is disposed, a region having a predetermined width (for example, 640 μm) is arbitrarily selected. The vertical width of the wavelength conversion layer is measured by visually adjusting two parallel lines perpendicular to the thickness direction of the wavelength conversion layer so that each of the parallel lines coincides with the upper and lower surfaces of the wavelength conversion layer, and the vertical width of the wavelength conversion layer is measured as the distance between the two lines. The predetermined horizontal width of the wavelength conversion layer is multiplied by the vertical width of the wavelength conversion layer to calculate the cross-sectional area of ​​the wavelength conversion layer to be measured.

[0040] The sum of the phosphor particle cross-sectional areas is calculated as the sum of the cross-sectional areas of each phosphor particle observed in the cross section of the wavelength conversion layer to be measured. The cross-sectional area of ​​each phosphor particle in the cross section of the wavelength conversion layer is measured as the cross-sectional area of ​​a particle identified as a phosphor particle in a backscattered electron image obtained by observing the cross section of the wavelength conversion layer to be measured with a scanning electron microscope (SEM). The cross-sectional ratio is calculated by dividing the calculated sum of the phosphor particle cross-sectional areas by the cross-sectional area of ​​the wavelength conversion layer.

[0041] The average thickness of the wavelength conversion layer may be, for example, 55 μm or more and 146 μm or less, preferably 60 μm or more or 75 μm or more, and preferably 145 μm or less, 140 μm or less, or 120 μm or less. When the average thickness of the wavelength conversion layer is within the above range, the total efficiency of the light emitting device tends to be improved. The thickness of the wavelength conversion layer is calculated by subtracting the arithmetic mean value of the thickness of the substrate from the arithmetic mean value of the total thickness of the wavelength conversion layer and the substrate. The arithmetic mean value of the total thickness of the wavelength conversion layer and the substrate and the arithmetic mean value of the thickness of the substrate are each calculated from measurements at any six points. The total thickness of the wavelength conversion layer and the substrate and the thickness of the substrate are measured, for example, by a contact thickness measuring device.

[0042] The wavelength conversion layer may have a substantially uniform thickness. The variation coefficient of the thickness of the wavelength conversion layer may be, for example, 0.4 or less, preferably 0.3 or less. The lower limit of the variation coefficient of the thickness of the wavelength conversion layer may be, for example, 0.09 or more. The variation coefficient of the thickness of the wavelength conversion layer is calculated by dividing the standard deviation of the thickness of the wavelength conversion layer by the average thickness of the wavelength conversion layer.

[0043] In one embodiment, the wavelength converting member may include a disk-shaped substrate having a reflective surface, and a wavelength converting layer disposed in an annular shape on the reflective surface of the substrate along the circumference of the substrate.

[0044] Method for manufacturing wavelength conversion member The method for producing a wavelength conversion member may include a step of applying a phosphor composition containing a binder, a solvent, and a phosphor onto a substrate, and a heat treatment step of heat treating the phosphor composition applied onto the substrate to form a wavelength conversion layer. The solvent constituting the phosphor composition may have a boiling point of 200° C. or more and 300° C. or less. The phosphor composition may have a mass ratio of the solvent to the binder of 0.01 or more and 0.4 or less, and a mass ratio of the phosphor to the binder of 3.15 or more and 6.05 or less.

[0045] By containing a specific content of a solvent having a specific boiling point in the phosphor composition forming the wavelength conversion layer, a wavelength conversion layer having a desired average thickness can be efficiently formed with good productivity even when the phosphor content is high. The wavelength conversion layer formed has a high phosphor content and a predetermined average thickness, and therefore a light emitting device formed using the wavelength conversion member can achieve good total efficiency.

[0046] The phosphor composition includes at least a binder, a solvent, and a phosphor. The binder included in the phosphor composition may be an organic binder or an inorganic binder. The organic binder may include, for example, a resin, preferably a light-transmitting resin. Examples of the resin include thermosetting resins such as epoxy resin, silicone resin, epoxy-modified silicone resin, and modified silicone resin. When the resin includes a silicone resin, the resin tends to have better heat resistance, light resistance, and the like. The silicone resin or modified silicone resin may include at least one selected from the group consisting of a phenyl silicone resin, a modified phenyl silicone resin, a dialkyl silicone resin, and a modified dialkyl silicone resin. Examples of the inorganic binder include glass, ceramics, and aluminum oxide.

[0047] The phosphor contained in the phosphor composition may include at least one rare earth aluminate phosphor, for example. The details of the rare earth aluminate phosphor are as described above. The content of the phosphor in the phosphor composition may be, for example, 3.15 or more and 6.05 or less, preferably 3.5 or more, or 4 or more, and preferably 6 or less, as a mass ratio to the binder. When the content of the phosphor is within the above range, the total efficiency of the light emitting device tends to be higher.

[0048] The solvent contained in the phosphor composition may have a boiling point of, for example, 200°C or more and 300°C or less, preferably 210°C or more or 230°C or more, and preferably 280°C or less, 260°C or less, or 250°C or less. When the boiling point of the solvent is within the above range, the workability in the application step tends to be improved. From the viewpoint of the solubility of the binder, the solvent may contain, for example, an aliphatic hydrocarbon solvent, and may contain at least one selected from the group consisting of aliphatic hydrocarbon solvents having 12 to 16 carbon atoms. The solvent may preferably contain at least one selected from the group consisting of dodecane (boiling point 216°C), tridecane (boiling point 234°C), tetradecane (boiling point 254°C), pentadecane (boiling point 271°C), and hexadecane (boiling point 287°C).

[0049] The content of the solvent in the phosphor composition may be, for example, 0.01 or more and 0.4 or less, preferably 0.02 or more, 0.04 or more, or 0.05 or more, and preferably 0.38 or less, 0.35 or less, 0.3 or less, 0.2 or less, or 0.1 or less, as a mass ratio of the solvent to the total mass of the binder and the phosphor. The content of the solvent in the phosphor composition may be, for example, 0.002 or more and 0.06 or less, preferably 0.01 or more, or 0.05 or less, as a mass ratio of the solvent to the total mass of the binder and the phosphor. When the content of the solvent is within the above range, the workability in the application step tends to be further improved.

[0050] The phosphor composition can be prepared, for example, by mixing a binder, a solvent, and a phosphor. Alternatively, the phosphor composition may be prepared by mixing a mixture of a binder and a solvent with a phosphor. The mixing method can be appropriately selected from commonly used mixing methods. Examples of the mixing method include a method using a vacuum degassing mixer, a stirrer, etc.

[0051] In the application step, the phosphor composition is applied to a substrate. Details of the substrate to which the phosphor composition is applied are as described above. The phosphor composition may be applied preferably on a reflective surface of the substrate. Methods for applying the phosphor composition to the substrate include printing, coating, and adhesion of a phosphor composition sheet. The method for applying the phosphor composition to the substrate may preferably be a printing method.

[0052] The application of the phosphor composition by the printing method can be performed by screen printing, for example, by placing a screen plate at a desired position on the substrate, and moving a squeegee on the placed screen plate to transmit the phosphor composition and form a phosphor composition layer of a predetermined thickness on the substrate. This allows the phosphor composition to be applied to the substrate with a substantially uniform thickness. In addition, the thickness of the phosphor composition layer formed can be adjusted by using a screen plate in which the line diameter, linearity, gauze thickness, aperture ratio, mesh number, etc. of the fibers constituting the screen are appropriately adjusted. The thickness of the phosphor composition layer formed on the substrate may be appropriately adjusted according to the thickness of the intended wavelength conversion layer. In addition, the amount of the phosphor composition applied may be such that the wavelength conversion layer formed has a desired thickness. The average thickness of the wavelength conversion layer formed may be, for example, 55 μm or more and 146 μm or less, preferably 60 μm or more or 75 μm or more, and preferably 145 μm or less, 140 μm or less, or 120 μm or less.

[0053] In the heat treatment step, the phosphor composition applied on the substrate is heat-treated to form a wavelength conversion layer. The heat treatment step may include thermally curing the binder contained in the phosphor composition to form a wavelength conversion layer. The heat treatment temperature in the heat treatment step may be appropriately set according to the thermosetting characteristics of the binder. The heat treatment temperature may be, for example, a temperature lower than the boiling point of the solvent contained in the phosphor composition. This can suppress the formation of voids and the like due to the volatilization of the solvent. The heat treatment temperature may be, for example, 50°C or higher and 180°C or lower, and preferably 100°C or higher or 150°C or lower. The heat treatment time may be, for example, 1 hour or higher and 10 hours or lower, and preferably 4 hours or higher or 8 hours or lower. The heat treatment atmosphere may be, for example, an air atmosphere.

[0054] In the heat treatment step, at least a part of the solvent contained in the phosphor composition may be removed prior to thermal curing of the binder. The removal of the solvent can be performed, for example, by heating or reducing pressure on the phosphor composition. When the solvent is removed by heating, the temperature may be, for example, 50°C or more and 180°C or less, and preferably 100°C or more or 150°C or less. The time for removing the solvent may be, for example, 1 hour or more and 10 hours or less, and preferably 4 hours or more or 8 hours or less.

[0055] Light-emitting device The light emitting device comprises a wavelength conversion member of the first embodiment, a motor for rotating the wavelength conversion member, and a light source for irradiating the wavelength conversion member with light. The light emitting device is configured to emit a mixed color light of light from the light source and light from the wavelength conversion member irradiated with the light from the light source. By including a wavelength conversion member having a specific configuration, the light emitting device can achieve good total efficiency. Details of the wavelength conversion member constituting the light emitting device are as described above.

[0056] In the light emitting device, the wavelength conversion member is fixed to the rotation shaft of the motor and arranged so as to be rotatable by the motor. Examples of the light source that irradiates the wavelength conversion member with light include a light emitting element. The light emitting element may be a semiconductor light emitting element, a light emitting diode, or a laser diode. The light source may be composed of one type of light emitting element alone or a combination of two or more types. Furthermore, the light emitting element that constitutes the light source may be one or more.

[0057] The light source may have an emission peak wavelength within the wavelength range of, for example, 440 nm to 470 nm. The emission peak wavelength of the light source may preferably be within the wavelength range of, for example, 450 nm to 460 nm. The half-width of the light source may be, for example, 30 nm or less.

[0058] The output of the light source is, for example, 0.5 W / mm as the optical power density irradiated to the wavelength conversion member. 2 or more, preferably 5 W / mm 2 or more than 10W / mm 2 The upper limit of the output of the light-emitting element is, for example, 1000 W / mm 2 may be less than or equal to 500 W / mm 2 or less than 150W / mm 2 It may be the following:

[0059] The light emitting device can be used to configure a projector, which will be described later. By using a light emitting device that exhibits good total efficiency, a high-output projector can be configured. The light emitting device can be used not only as a light source device for a projector, but also as a light emitting device provided in a light source in a general lighting device such as a ceiling light, a special lighting device such as a spotlight, stadium lighting, and studio lighting, a vehicle lighting device such as a headlamp, a projection device such as a head-up display, an endoscope light, an imaging device such as a digital camera, a mobile phone, and a smartphone, a monitor for a personal computer (PC), a notebook personal computer, a television, a personal digital assistant (PDX), a smartphone, a tablet PC, a liquid crystal display device such as a mobile phone, and the like.

[0060] projector The projector includes the above-mentioned light emitting device, an image display system, and a projection optical system. An example of the configuration of the projector will be described with reference to FIG. 2. FIG. 2 is a schematic configuration diagram of a projector 100. The projector 100 includes a light source 110, a wavelength conversion member 50, an image display system 120, and a projection optical system 130. In the projector 100, a mixture of light from the light source 110 and light obtained by wavelength-converting the light from the light source 110 by the wavelength conversion member 50 is irradiated onto the image display system 120. The image display system 120 converts the irradiated light into an image and projects it to the outside via the projection optical system 130.

[0061] The details of the light source 110 and the wavelength conversion member 50 constituting the projector 100 are as described above. The image display system 120 displays an image projected by the projector 100. A liquid crystal panel, a digital mirror device (DMD), or the like can be used for the image display system 120. The projection optical system 130 projects to the outside an image obtained by converting the light emitted from the wavelength conversion member 50 by the image display system 120. The projection optical system 130 is composed of a plurality of lenses 131, and can adjust zoom and focus. In addition to the above configuration, the projector 100 is composed of the lenses 131, a dichroic mirror 132, and the like. Depending on the design of the projector 100, a mirror, a dichroic mirror, a lens, a prism, and the like not shown in FIG. 2 may be further provided.

[0062] The present invention may include the following aspects. [1] A wavelength converting member comprising: a substrate; and a wavelength converting layer disposed on the substrate and containing a binder and a phosphor, wherein the volume ratio of the phosphor to the binder is between 0.75 and 1.45, and the wavelength converting layer has an average thickness of between 55 μm and 146 μm.

[0063] [2] A wavelength conversion member comprising: a substrate; and a wavelength conversion layer disposed on the substrate and containing a binder and a phosphor, wherein in a cross section perpendicular to the surface on which the wavelength conversion layer is disposed on the substrate, the ratio of the sum of the cross-sectional areas of the phosphor particles to the cross-sectional area of ​​the wavelength conversion layer is 56% or more and 70% or less, and the average thickness is 55 μm or more and 146 μm or less.

[0064] [3] The wavelength conversion member according to [1] or [2], wherein the phosphor comprises a rare earth aluminate phosphor having a composition including at least one first element selected from the group consisting of yttrium, lanthanum, lutetium, gadolinium, and terbium, at least one element selected from the group consisting of aluminum, gallium, and scandium, a second element including at least aluminum, and cerium.

[0065] [4] The wavelength conversion member according to any one of [1] to [3], wherein the phosphor has a median particle size of 15 μm or more and 40 μm or less.

[0066] [5] The wavelength conversion member according to any one of [1] to [4], wherein the substrate has a reflective surface made of a material containing at least one selected from the group consisting of silver and aluminum, and the wavelength conversion layer is disposed on the reflective surface.

[0067] [6] The wavelength conversion member according to any one of [1] to [5], wherein the binder contains a silicone resin.

[0068] [7] A light emitting device comprising: a wavelength conversion member according to any one of [1] to [6]; a motor for rotating the wavelength conversion member; and a light source for irradiating the wavelength conversion member with light.

[0069] [8] A projector comprising the light-emitting device according to [7], an image display system, and a projection optical system.

[0070] [9] A method for manufacturing a wavelength conversion member, comprising: applying onto a substrate a phosphor composition comprising a binder, a solvent, and a phosphor, wherein the boiling point of the solvent is 200°C or more and 300°C or less, the mass ratio of the solvent to the binder is 0.01 or more and 0.4 or less, and the mass ratio of the phosphor to the binder is 3.15 or more and 6.05 or less; and heat-treating the phosphor composition applied to the substrate to form a wavelength conversion layer.

[0071]

[10] The method for producing a wavelength conversion member according to [9], wherein applying the phosphor composition onto a substrate includes screen-printing the phosphor composition.

[0072]

[11] The method for producing a wavelength conversion member according to [9] or

[10] , wherein the heat treatment of the phosphor composition includes a heat treatment at less than 200°C.

[0073]

[12] The method for manufacturing a wavelength conversion member according to any one of [9] to

[11] , wherein the phosphor contains a rare earth aluminate phosphor having a composition including at least one first element selected from the group consisting of yttrium, lanthanum, lutetium, gadolinium, and terbium, at least one element selected from the group consisting of aluminum, gallium, and scandium, a second element containing at least aluminum, and cerium.

[0074]

[13] The method for producing a wavelength conversion member according to any one of [9] to

[12] , wherein the phosphor has a median particle size of 15 μm or more and 40 μm or less.

[0075]

[14] The method for producing a wavelength conversion member according to any one of [9] to

[13] , wherein the solvent contains at least one selected from the group consisting of dodecane, tridecane, tetradecane, pentadecane, and hexadecane.

[0076]

[15] The method for manufacturing a wavelength conversion member described in any one of [9] to

[14] , wherein the substrate has a reflective surface made of a material containing at least one selected from the group consisting of silver and aluminum, and applying the phosphor composition onto the substrate includes applying the phosphor composition to the reflective surface. 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] Phosphor As phosphors, a rare earth aluminate phosphor having a theoretical composition represented by the following formula and a median particle size of 24 μm and a rare earth aluminate phosphor having a median particle size of 31 μm were prepared. Y3Al5O 12 :Ce

[0079] substrate The substrate was a disk-shaped substrate made of aluminum-containing metal with a diameter of 33 mm and a thickness of 0.47 mm. The specular reflectance of the reflective surface of the substrate for light of 450 nm was 89%.

[0080] Example 1 5 parts by mass of dodecane was added to 100 parts by mass of dimethyl silicone resin, and mixed using a vacuum defoaming mixer. 400 parts by mass of rare earth aluminate phosphor with a central particle size of 24 μm was added thereto, and mixed using a vacuum defoaming mixer to obtain a phosphor composition. The obtained phosphor composition was applied to a substrate by screen printing to form a phosphor composition layer. Thereafter, the substrate was heat-treated in an oven at 60° C. for 4 hours, and then in an oven at 150° C. for 4 hours to form a wavelength conversion layer, and the wavelength conversion member of Example 1 was obtained.

[0081] Examples 2 to 16, Comparative Example 1 and Comparative Example 2 Each wavelength conversion member was obtained in the same manner as in Example 1, except that the median particle size and amount of phosphor added, and the type and amount of solvent added were changed as shown in Table 1.

[0082] For the wavelength conversion member obtained above, the volume ratio of the phosphor to the binder in the wavelength conversion layer and the average thickness of the phosphor layer were measured as follows. The results are shown in Table 1.

[0083] Measurement of volume ratio The density of dimethyl silicone resin is 1.1 g / cm 3 The mass of the dimethyl silicone resin added to the phosphor composition was divided by its density to calculate the volume of the dimethyl silicone resin in the phosphor composition. The density of the rare earth aluminate phosphor was set to 4.6 g / cm. 3 The mass of the rare earth aluminate phosphor added to the phosphor composition was divided by its density to calculate the volume of the rare earth aluminate phosphor in the phosphor composition. The volume of the rare earth aluminate phosphor was divided by the volume of the dimethyl silicone resin contained in the phosphor composition to calculate the volume ratio of the phosphor to the binder in the formed wavelength conversion layer.

[0084] Measurement of average thickness The average thickness of the wavelength conversion layer was calculated by subtracting the arithmetic mean value of the thickness of the substrate alone measured at six points from the arithmetic mean value of the total thickness of the wavelength conversion layer and the substrate measured at six points. The total thickness of the wavelength conversion layer and the substrate and the thickness of the substrate alone were measured using a contact thickness gauge.

[0085] Relative Total Efficiency For the wavelength conversion member obtained above, the fluorescence efficiency and light collection efficiency of the light emitting device were calculated as follows, and the total efficiency was calculated as the product of the fluorescence efficiency and the light collection efficiency. The total efficiency of each light emitting device is shown in Table 1 as a relative total efficiency with the total efficiency of the light emitting device using the wavelength conversion member of Comparative Example 1 as the reference (100%).

[0086] A light emitting device as shown in Figure 1 was prepared for measuring the total efficiency. The wavelength conversion member was fixed to the rotating shaft of a motor and was made rotatable by the motor. The motor rotation speed was set to 7200 rpm, and the fluorescence efficiency and light collection efficiency were measured as follows.

[0087] Fluorescence Efficiency For the wavelength conversion members of each of the Examples and Comparative Examples, laser light from a laser diode having a wavelength of 450 nm was incident on the wavelength conversion members with a diameter of 0.25 mm. 2 The laser light was irradiated at an intensity of 10 W through a dichroic mirror so that it was incident on the wavelength conversion member. The radiant flux of the light emitted from the same surface as the surface on which the laser light was incident was separated by a dichroic mirror, and the intensity of the emitted light was measured using an integrating sphere. The fluorescence efficiency was calculated by dividing the intensity of the emitted light by the intensity of the incident light.

[0088] Light collection efficiency The wavelength conversion members of each Example and Comparative Example were irradiated with laser light from a laser diode having a wavelength of 455 nm. This irradiation was performed so that the diameter of the incident light was 0.6 mm on the upper surface of the wavelength conversion member into which the laser light was incident. Next, the outgoing light emitted from the same surface as the upper surface of the wavelength conversion member into which the laser light was incident was measured by the following method. First, the emission luminance of the light emitted from the wavelength conversion member of each Example and Comparative Example was measured with a color luminance meter, and the position showing the maximum luminance in the obtained emission spectrum was set as the center (measurement center), and the distance (mm) from the measurement center to two positions where the luminance was 1 / 100 (1%) of the maximum luminance in the emission spectrum was measured as an absolute value. Then, the sum of the distances (mm) from the measurement center to the two positions was calculated. This value is called the "1% width (mm)". The smaller the value of this 1% width, the narrower the area in which light is emitted, and the easier it is for light to enter the secondary optical system, resulting in a higher light collection efficiency. Comparing the obtained 1% width value with the light collection efficiency (=emission output x 100 / fluorescence output) measured with a typical actual secondary optical system, it is found that the light collection efficiency can be approximated by the following formula, where the 1% width value is x. Using this formula, the light collection efficiency was calculated from the measured 1% width value. Light collection efficiency = -0.0012x 2 +0.1243x+58.783

[0089] [Table 1]

[0090] As shown in Table 1, the volume ratio of the phosphor to the binder in the wavelength conversion layer was 0.75 to 1.45, and the average thickness of the wavelength conversion layer was 55 μm to 146 μm, so that the light emitting device according to the example had a higher total efficiency than the light emitting device according to the comparative example. Also, as shown in Table 1, by using a solvent having a boiling point of 200° C. to 300° C., such as dodecane (boiling point 216° C.), tridecane (boiling point 234° C.), and hexadecane (boiling point 287° C.), the mass ratio of the solvent to the binder was 0.01 to 0.4, and the mass ratio of the phosphor to the binder was 3.15 to 6.05, the wavelength conversion layer was formed with a thickness of, for example, 55 μm to 146 μm, so that the light emitting device obtained by the manufacturing method according to the example had a higher total efficiency than the light emitting device according to the comparative example.

[0091] For representative wavelength conversion members obtained above, the ratio of the sum of the phosphor particle cross-sectional areas to the cross-sectional area of ​​the wavelength conversion layer (cross-sectional ratio) was evaluated as follows. The results are shown in Table 2.

[0092] Cross-sectional ratio evaluation A cross-sectional SEM image (width: 640 μm) of the wavelength conversion layer obtained using a scanning electron microscope (SEM) was analyzed using image analysis software (ImageJ), and particles in which the cross-sectional outline of each phosphor could be confirmed in the cross-sectional SEM image were binarized. The cross-sectional area of ​​each binarized phosphor particle was added up to calculate the total cross-sectional area of ​​the phosphor. The cross-sectional area of ​​the wavelength conversion layer was calculated by visually adjusting the positions of two parallel lines perpendicular to the thickness direction of the wavelength conversion layer so that the wavelength conversion layer was sandwiched between them, and multiplying the vertical width of the wavelength conversion layer, measured as the distance between the two parallel lines, by the horizontal width of 640 μm. Next, the cross-sectional ratio (%) was calculated by dividing the total cross-sectional area of ​​the phosphor by the cross-sectional area of ​​the wavelength conversion layer.

[0093] [Table 2] [Industrial Applicability]

[0094] The wavelength conversion member according to the present disclosure and a light emitting device including the same can be used as a light source device for a projector, an illumination device, an automobile display, a backlight source for a liquid crystal display, and the like. [Explanation of symbols]

[0095] 100 projector; 110 light source; 50 wavelength conversion member; 130 projection optical system; 200 light emitting device

Claims

1. applying a phosphor composition containing a binder, a solvent, and a phosphor, the solvent having a boiling point of 200° C. or more and 300° C. or less, a mass ratio of the solvent to the binder being 0.05 or more and 0.35 or less, and a mass ratio of the phosphor to the binder being 4 or more and 6 or less, onto a substrate; and heat treating the phosphor composition applied on the substrate to form a wavelength conversion layer, the phosphor includes a rare earth aluminate phosphor having a composition including at least one first element selected from the group consisting of yttrium, lanthanum, lutetium, gadolinium, and terbium, at least one second element selected from the group consisting of aluminum, gallium, and scandium, and including at least aluminum, and cerium; The median particle size is 15 μm or more and 40 μm or less, In the volume-based particle size distribution, the particle size D corresponding to 10% of the cumulative volume from the small diameter side １０ Particle size D corresponding to 90% cumulative volume ９０ The ratio (D ９０ / D １０ ) is 3.0 or less.

2. The method for producing a wavelength conversion member according to claim 1 , wherein applying the phosphor composition onto a substrate comprises screen-printing the phosphor composition.

3. The method for producing a wavelength conversion member according to claim 1 , wherein the heat treatment of the phosphor composition includes a heat treatment at a temperature of less than 200° C.

4. The method for producing a wavelength conversion member according to claim 1 , wherein the solvent contains at least one selected from the group consisting of dodecane, tridecane, tetradecane, pentadecane, and hexadecane.

5. 2. The method for manufacturing a wavelength conversion member according to claim 1, wherein the substrate has a reflective surface made of a material containing at least one selected from the group consisting of silver and aluminum, and applying the phosphor composition onto the substrate includes applying the phosphor composition to the reflective surface.

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