Wavelength conversion member and light emitting device

Abstract

To provide a wavelength conversion member having higher intensity of output light.SOLUTION: A wavelength conversion member includes a support, and a wavelength conversion layer which is arranged on the support and has a phosphor layer containing a phosphor with a composition expressed by Formula (1). The wavelength conversion member is configured so that a thickness of the phosphor layer is 5 μm or more and 155 μm or less, and in a cross section of the wavelength conversion layer orthogonal to an arrangement surface of the support, a ratio of a total sum of particle cross sectional areas of the phosphor is 5% or more and less than 40% with respect to a cross sectional area of the wavelength conversion layer. (In Formula (1), M1 is at least one kind selected from rare earth elements other than La and Ce, a total molar content of Y, Gd, Lu in the M1 is 90% or more, p, q, r and s satisfy 2.7≤p+q+r≤3.3, 0≤r≤1.2, 10≤s≤12, and 0<q≤1.2. The Formula (1) is: LapCeqM1rSi6 Ns.SELECTED DRAWING: Figure 1B

Description

[Technical field]

[0001] The present disclosure relates to a wavelength conversion member and a light emitting device. [Background technology]

[0002] In an image projection device (projector) that displays a color image by projecting light emitted from a light source device onto a screen using a micromirror, there is a demand for a higher output from the light source device. For example, Patent Document 1 proposes a projector that includes a phosphor wheel, which includes a disk-shaped support and a phosphor layer formed from a specific phosphor and a light-transmitting inorganic material, as a wavelength conversion member in a part of the light source device. In order to increase the output of the light source device, there is a demand for a higher emission intensity of the output light from the wavelength conversion member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-039992 A 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 and a light emitting device that output light with a higher intensity. [Means for solving the problem]

[0005] A first aspect is a wavelength conversion member comprising a support and a wavelength conversion layer disposed on the support and having a phosphor layer containing a phosphor whose composition is represented by the following formula (1). The thickness of the phosphor layer in the wavelength conversion member is 5 μm or more and 155 μm or less. In the wavelength conversion member, the ratio of the sum of the cross-sectional areas of phosphor particles in a cross section perpendicular to the arrangement surface of the wavelength conversion layer on the support to the cross-sectional area of ​​the wavelength conversion layer may be 5% or more and less than 40%. La pCe q M 1 r Si6N s (1)

[0006] In the formula (1), M 1 represents at least one selected from rare earth elements other than La and Ce, and the total molar content of Y, Gd, and Lu in M 1 is 90% or more, and p, q, r, and s satisfy 2.7 ≦ p + q + r ≦ 3.3, 0 ≦ r ≦ 1.2, 10 ≦ s ≦ 12, and 0 < q ≦ 1.2.

[0007] The second aspect is a light-emitting device including the wavelength conversion member and a light-emitting element having an emission peak wavelength within a wavelength range of 350 nm or more and 500 nm or less.

Effects of the Invention

[0008] According to one aspect of the present disclosure, it is possible to provide a wavelength conversion member and a light-emitting device having a greater intensity of output light.

Brief Description of the Drawings

[0009] [Figure 1A] It is a schematic plan view of the wavelength conversion member seen from the main surface side. [Figure 1B] It is a schematic side view of the wavelength conversion member seen from the side, and a partially enlarged view thereof. [Diagram 2] It is a schematic configuration diagram showing an example of the light-emitting device and a partially enlarged view thereof. [Diagram 3] It is a schematic configuration diagram showing another example of the light-emitting device and a partially enlarged view thereof. [Figure 4] It is a diagram showing the change in the emission intensity of the light emitted from the wavelength conversion member with respect to the output density of the excitation light source. [Diagram 5] It is a diagram showing the change in the emission intensity of the emitted light with respect to the thickness of the phosphor layer in the wavelength conversion member. [Figure 6] It is a partially enlarged cross-sectional view of the wavelength conversion member. [Figure 7] It is a partially enlarged cross-sectional view in the vicinity of the measurement position P in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In this specification, 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. Hereinafter, an embodiment of the present invention will be described in detail. However, the embodiment shown below is an example of a wavelength conversion member and a light emitting device for embodying the technical idea of ​​the present invention, and the present invention is not limited to the wavelength conversion member and the light emitting device shown below. Note that the members shown in the claims are in no way limited to the members of the embodiment. In particular, the dimensions, materials, shapes, and relative positions of the components described in the embodiment are merely explanatory examples, and are not intended to limit the scope of the present invention, unless otherwise specified. Note that the size and positional relationship of the components shown in each drawing may be exaggerated to clarify the explanation. Furthermore, in the following explanation, the same names and symbols indicate the same or similar components, and detailed explanations are omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that multiple elements are composed of the same material, and one material may serve multiple elements, or conversely, the function of one material may be shared by multiple materials. Also, the contents described in some examples and embodiments may be applicable to other examples and embodiments.

[0011] Wavelength conversion material The wavelength conversion member includes a support and a wavelength conversion layer disposed on the support, the wavelength conversion layer including a phosphor layer containing a phosphor. The phosphor has a composition represented by the following formula (1), for example. The phosphor layer has a thickness of 5 μm or more and 155 μm or less. In addition, in a cross section perpendicular to the surface on which the wavelength conversion layer is disposed on the support, the ratio of the sum of the particle cross-sectional areas of the phosphor to the cross-sectional area of ​​the wavelength conversion layer may be 5% or more and less than 40%.

[0012] La p Ceq M 1 r Si6N s (1)

[0013] In the formula (1), M 1 represents at least one selected from rare earth elements other than La and Ce, and the total molar content of Y, Gd, and Lu in M 1 is 90% or more, and p, q, r, and s satisfy 2.7 ≤ p + q + r ≤ 3.3, 0 ≤ r ≤ 1.2, 10 ≤ s ≤ 12, and 0 < q ≤ 1.2.

[0014] The wavelength conversion member has a specific composition, and when a phosphor layer containing a phosphor activated by cerium (Ce) has a specific thickness, when constituting a light emitting device in which the phosphor and the light emitting device are combined, the emission intensity of the output light is further improved. Furthermore, the emission intensity of the output light also increases in proportion to the output of the light emitting element, and it can exhibit excellent linearity in emission characteristics and excellent emission characteristics.

[0015] First phosphor The emission peak wavelength of the phosphor (hereinafter also referred to as the first phosphor) constituting the phosphor layer of the wavelength conversion member can be adjusted according to the required wavelength region, and can be freely adjusted as long as it is within the range reproduced by the phosphor having the composition represented by formula (1). The emission peak wavelength of the first phosphor may be, for example, 480 nm or more and 620 nm or less. When the emission intensity on the short wavelength side (e.g., green) is particularly increased, the emission peak wavelength of the first phosphor may be 480 nm or more and 550 nm or less, and the lower limit may be preferably 500 nm or more, 510 nm or more, or 520 nm or more, and the upper limit may be preferably 545 nm or less, 540 nm or less, or 530 nm or less. In addition, when the emission intensity on the long wavelength side (e.g., red) is particularly increased, it may be 530 nm or more and 620 nm or less, and the lower limit may be preferably 540 nm or more, 550 nm or more, or 570 nm or more, and the upper limit may be preferably 610 nm or less, or 600 nm or less. The emission peak wavelength of the first phosphor can also be increased overall from the emission intensity on the short wavelength side to the emission intensity on the long wavelength side, and may be, for example, 520 nm or more and 580 nm or less. When the emission peak is within the above wavelength range, the emission intensity on the short wavelength side and the emission intensity on the long wavelength side in the emission spectrum can be selected as necessary, and the color reproducibility can be improved and controlled.

[0016] For example, in the composition of the first phosphor, the luminous intensity on the long wavelength side can be increased by increasing the content of cerium. In this case, by appropriately controlling the content of cerium, it is possible to suppress concentration quenching, deterioration of temperature characteristics, etc., and to suppress the decrease in luminous efficiency in high-output excitation. In addition, it is possible to replace a part of lanthanum with a rare earth element M such as yttrium or gadolinium, which has a smaller ionic radius. 1By replacing with, it is possible to increase the emission intensity on the long wavelength side. In this case, by appropriately controlling the content of the substitution element, it is possible to suppress the generation of distortion and defects in the crystal structure, and it is possible to suppress the saturation of brightness with respect to the excitation light, the decrease in linearity with respect to the excitation light output, etc. In this way, when considering color rendering properties, color reproducibility, etc. in using phosphors under high-output excitation, it is desirable to also consider factors such as substitution elements and activating elements.

[0017] The half-width in the emission spectrum of the first phosphor may be, for example, 100 nm or more, preferably 110 nm or more, 115 nm or more, or 120 nm or more. The upper limit of the half-width may be, for example, 150 nm or less, preferably 140 nm or less, or 130 nm or less. When the half-width of the first phosphor is within the above range, the light emitting device tends to have a higher emission intensity, and the emission intensity on the long wavelength side of the emission spectrum tends to be higher.

[0018] The composition of the first phosphor is lanthanum (La), cerium (Ce), and a rare earth element M other than lanthanum (La) and cerium (Ce). 1 The first phosphor may contain at least one of the above, silicon (Si), and nitrogen (N). Cerium may be included in the composition of the first phosphor as an activator element and may be the luminescence center of the first phosphor. 1 may be at least one selected from the group consisting of scandium (Sc), yttrium (Y), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). 1 may contain at least one element selected from the group consisting of yttrium (Y), gadolinium (Gd) and lutetium (Lu), and preferably contains at least yttrium (Y). 1The total molar content of yttrium (Y), gadolinium (Gd) and lutetium (Lu) with respect to the total molar amount of may be, for example, 90% or more, preferably 95% or more, or 98% or more. 1 The molar content of yttrium (Y) relative to the total molar amount may be, for example, 90% or more, preferably 95% or more, or 98% or more.

[0019] The composition of the first phosphor may have a molar content of lanthanum of 0.3 to 3.0, preferably 1.2 to 2.5, relative to 6 moles of silicon. 1 The molar content ratio of cerium in the composition of the first phosphor may be 0 or more and 1.2 or less, and preferably 0.3 or more and 1.0 or less. The molar content ratio of cerium in the composition of the first phosphor may be greater than 0 and 1.2 or less, and preferably 0.15 or more and 1.0 or less. The molar content ratio of nitrogen in the composition of the first phosphor may be 10 or more and 12 or less, and preferably 10.5 or more and 11.5 or less. The first phosphor may have a composition represented by the following formula (1), for example.

[0020] La p Ce q M 1 r Si6N s (1)

[0021] In the above formula (1), M 1 represents at least one rare earth element other than La and Ce. 1 may contain at least one selected from the group consisting of Y, Gd and Lu, and preferably contains at least Y. 1 The total molar content of at least one element selected from Y, Gd and Lu in M ​​is 90% or more, preferably 95% or more. 1The molar content of Y therein may be 90% or more, preferably 95% or more. p, q, r, and s satisfy 2.7 ≦ p + q + r ≦ 3.3, 0 ≦ r ≦ 1.2, 10 ≦ s ≦ 12, and 0 < q ≦ 1.2, and preferably satisfy 2.9 ≦ p + q + r ≦ 3.1, 0.3 ≦ r ≦ 1.0, 10.5 ≦ s ≦ 11.5, and 0 < q ≦ 1.0. p may satisfy 0.3 ≦ p ≦ 3.0, and preferably satisfies 1.2 ≦ p ≦ 2.5.

[0022] In the composition of the first phosphor, the rare earth element M 1 A part of may be substituted with at least one selected from the group consisting of Group 2 elements, and preferably may be substituted with at least one selected from the group consisting of Mg and alkaline earth metal elements. The rare earth element M 1 When a part of is substituted with other elements other than rare earth elements, the rare earth element M 1 The molar content of other elements in is, for example, 10% or less, preferably 5% or less, or 3% or less. The lower limit of the molar content of other elements may be, for example, 0.01% or more, and preferably 1% or more. The rare earth element M 1 When a part of is substituted with other elements, the total molar content of yttrium (Y), gadolinium (Gd), and lutetium (Lu) with respect to the total molar amount of the rare earth element M 1 contained in the first phosphor may be, for example, 90% or more, preferably 95% or more, or 98% or more. Also, the molar content of yttrium (Y) with respect to the total molar amount of the rare earth element M 1 contained in the first phosphor may be, for example, 90% or more, preferably 95% or more, or 98% or more.

[0023] In the composition of the first phosphor, a part of silicon may be substituted with at least one selected from the group consisting of boron (B), aluminum (Al), gallium (Ga) and germanium (Ge). When a part of silicon is substituted with an element other than silicon, the molar content of the element other than silicon relative to the total molar amount of silicon and elements other than silicon in the composition is, for example, 50% or less, preferably 20% or less, or 10% or less. The lower limit of the molar content of the element other than silicon may be, for example, 0.01% or more, preferably 5% or more. When a part of silicon is substituted with an element other than silicon in the composition of the first phosphor, the total molar content of aluminum and silicon relative to the total molar amount of silicon and elements other than silicon may be, for example, 90% or more, preferably 95% or more, or 98% or more.

[0024] In the composition of the first phosphor, a part of the nitrogen may be replaced by an element other than nitrogen. Examples of elements other than nitrogen include oxygen, fluorine, and chlorine. The first phosphor may also be surface-treated with an oxide, hydroxide, fluoride, chloride, or the like in a form that replaces the nitrogen in the composition. When a part of the nitrogen is replaced by an element other than nitrogen, the molar content of the element other than nitrogen relative to the total molar amount of nitrogen and elements other than nitrogen in the composition may be, for example, 10% or less, preferably 5% or less, 3% or less, or 1% or less. The lower limit of the molar content of elements other than nitrogen may be 0.01% or more, preferably 0.1% or more, or 1% or more.

[0025] From the viewpoint of luminescence intensity, the particle size and particle size distribution of the first phosphor preferably show a single peak particle size distribution. The central particle size of the first phosphor may be, for example, 1 μm or more and 100 μm or less, and preferably 5 μm or more and 40 μm or less, taking into consideration the luminescence intensity and the workability in manufacturing the light emitting device. The lower limit of the central particle size of the first phosphor may be, for example, 7 μm or more, 10 μm or more, 12 μm or more, or 15 μm or more. The upper limit of the central particle size of the first phosphor may be 50 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, or 22 μm or less. Here, the central particle size of the phosphor is the particle size corresponding to 50% of the volume cumulative from the small particle size side in the volume-based particle size distribution.

[0026] The method for producing the first phosphor is not particularly limited, and can be appropriately selected from known means. For example, it can be produced as follows. The raw materials are simple substances, oxides, carbonates, nitrides, chlorides, fluorides, sulfides, etc. of the elements contained in the composition of the phosphor, and these raw materials are weighed to have a predetermined composition ratio. In addition, additive materials such as flux are appropriately added to the raw materials, and mixed wet or dry using a mixer. This makes it possible to promote a solid-phase reaction and form particles of uniform size. In addition, the mixer may be a ball mill that is commonly used in industry, or a pulverizer such as a vibration mill, roll mill, or jet mill. The specific surface area can also be increased by pulverizing using a pulverizer. In addition, in order to make the specific surface area of ​​the powder within a certain range, it can also be classified using a wet separator such as a sedimentation tank, hydrocyclone, or centrifuge, or a dry classifier such as a cyclone or air separator that is commonly used in industry. The above mixed raw materials are packed into a crucible of SiC, quartz, alumina, BN, or the like, and fired in an inert atmosphere such as argon or nitrogen, a reducing atmosphere containing hydrogen, or an oxidizing atmosphere in the air. Firing is performed at a specified temperature and time. The fired material is crushed, dispersed, filtered, or the like to obtain the desired phosphor powder. Solid-liquid separation can be performed by a method commonly used in industry, such as filtration, suction filtration, pressure filtration, centrifugation, or decantation. Drying can be performed by a device commonly used in industry, such as a vacuum dryer, a hot air heating dryer, a conical dryer, or a rotary evaporator.

[0027] The first phosphor constituting the phosphor layer may be one type alone or may be a combination of two or more types. When the phosphor layer contains two or more types of first phosphors, they may have different emission peak wavelengths and different compositions. When the phosphor layer contains two or more types of first phosphors, they may be included in the same phosphor layer or different phosphor layers. The different phosphor layers may be, for example, stacked and arranged on the support, or may be arranged in different regions on the support. The phosphor layer may contain a second phosphor in addition to the first phosphor. The second phosphor may be, for example, a phosphor that has a different composition from the first phosphor and allows the color of the output light to be adjusted. The content of the first phosphor relative to the total mass of the phosphors constituting the phosphor layer may be, for example, 50% by mass or more and 100% by mass or less, and may be preferably 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more.

[0028] The phosphor layer may contain a binder in addition to the first phosphor. Examples of the binder include inorganic materials such as glass and organic materials such as resin. The resin is preferably a light-transmitting resin, and examples of the resin include epoxy resin and silicone resin. When the wavelength conversion member contains a binder, the content of the binder in the wavelength conversion layer consisting of the phosphor layer and the light transmitting layer may be, for example, 15% by mass or more and 50% by mass or less, preferably 20% by mass or more or 25% by mass or more, and preferably 45% by mass or less or 40% by mass or less. The binder may be used alone or in combination of two or more types.

[0029] The thickness of the phosphor layer is 5 μm or more and 155 μm or less. This allows the wavelength conversion member to have a higher luminous intensity of output light. The lower limit of the thickness of the phosphor layer may be preferably 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. The upper limit of the thickness of the phosphor layer may be preferably 155 μm or less, 150 μm or less, 130 μm or less, 100 μm or less, 80 μm or less, 75 μm or less, or 70 μm or less. Here, the thickness of the phosphor layer means the thickness of the region in which the phosphor is present in the direction perpendicular to the support in the cross section of the wavelength conversion member perpendicular to the support. In addition, when multiple phosphor layers are stacked on the support, the thickness of the phosphor layer is the sum of the thicknesses of the phosphor layers.

[0030] Specifically, the thickness of the phosphor layer is measured as follows. In an image of a cross section of the phosphor layer in a direction perpendicular to the support, where the entire width of the phosphor layer can be observed, a perpendicular line to the surface of the support is set at a position halfway through the entire width of the phosphor layer. The thickness of the phosphor layer is determined by measuring the distance between the intersection of the perpendicular line and the interface between the support and the phosphor layer, and the intersection of the perpendicular line and the surface of the phosphor layer or the interface between the phosphor layer and the light-transmitting layer. For example, when the phosphor layer is provided with a predetermined width along the circumference of a disk-shaped support, the thickness of the phosphor layer may be measured for an image of a cross section that passes through the center of the disk, is perpendicular to the support, and includes the predetermined width of the phosphor layer as the entire width.

[0031] The thickness of the wavelength conversion layer consisting of the phosphor layer and the light transmitting layer, and the method of measuring the thickness of the phosphor layer will be described with reference to the drawings. FIG. 6 is a partially enlarged cross-sectional view of a wavelength conversion member in which a phosphor layer is provided with a predetermined width along the circumference of a disk-shaped support, and FIG. 7 is a partially enlarged cross-sectional view in the vicinity of the measurement position P in FIG. 6. As shown in FIG. 6, the thickness of the phosphor layer 52 is measured at the measurement position P, which is half the total width L of the phosphor layer 52 arranged on the support 54. At the measurement position P, a perpendicular line V to the surface of the support 54 is set as shown in FIG. 7. The distance between the intersection point P1 of the interface between the support 54 and the phosphor layer 80 and the perpendicular line V, and the distance between the intersection point P2 of the interface between the phosphor layer 80 and the light transmitting layer 82 and the perpendicular line V are measured to obtain the thickness 80T of the phosphor layer. The distance between the intersection point P1 of the interface between the support 54 and the phosphor layer 80 and the perpendicular line V, and the distance between the intersection point P3 of the surface of the light transmitting layer 82 and the perpendicular line V are measured to obtain the thickness 52T of the wavelength conversion layer. The thickness 82T of the light transmitting layer is calculated by subtracting the thickness 80T of the phosphor layer from the thickness 52T of the wavelength conversion layer.

[0032] In the wavelength conversion member, the thinner the phosphor layer containing the first phosphor, the higher the luminous intensity of the output light tends to be. That is, in the wavelength conversion member, the thickness of the phosphor layer containing the first phosphor and the luminous intensity of the output light may have a negative correlation.

[0033] When the median particle size of the first phosphor is, for example, 5 μm or more and 40 μm or less, or 10 μm or more and 35 μm or less, the ratio of the thickness of the phosphor layer to the median particle size of the first phosphor (thickness / median particle size) may be, for example, 1 or more and 40 or less, preferably 20 or less, 10 or less, or 5 or less, and preferably 2 or more, or 2.2 or more.

[0034] The phosphor layer is disposed, for example, on one of the main surfaces of the support, but may be disposed in a partial region of the main surface, or may be disposed over the entire surface or almost the entire surface of the main surface. The shape of the phosphor layer may be appropriately selected depending on the purpose, etc.

[0035] The phosphor layer may be part of a wavelength conversion layer that includes a phosphor and a binder. The wavelength conversion layer may have, for example, a phosphor layer disposed on a support and a light transmitting layer that includes a binder and is disposed on the phosphor layer.

[0036] The wavelength conversion layer may further contain other components in addition to the phosphor and the resin. 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 is not particularly limited and 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 resin.

[0037] The thickness of the wavelength conversion layer may be, for example, 5 μm to 400 μm, preferably 30 μm to 150 μm, 40 μm to 100 μm, or 50 μm to 100 μm. The thickness of the light transmission layer in the wavelength conversion layer may be, for example, 50 μm or less, preferably 40 μm or less, or 30 μm or less. The lower limit of the thickness of the light transmission layer may be, for example, greater than 0 μm, 5 μm or more, or 10 μm or more.

[0038] In a cross section of the wavelength conversion layer perpendicular to the support, the ratio of the sum of the particle cross-sectional areas of the phosphor to the cross-sectional area of ​​the wavelength conversion layer (hereinafter also referred to as the "cross-sectional ratio") may be, for example, 5% or more and less than 40%. The cross-sectional ratio may be preferably 7% or more, 10% or more, or 12% or more. The cross-sectional ratio may also be 35% or less, 30% or less, 28% or less, 25% or less, or 20% 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 particle cross-sectional areas of the phosphor 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 an image of a cross section of the wavelength conversion layer perpendicular to the main surface of the support on which the wavelength conversion layer is arranged, where the full width of the wavelength conversion layer can be observed, a perpendicular line to the surface of the support is set at a position halfway to the full width of the wavelength conversion layer. The distance between the intersection of the perpendicular line with the interface between the support and the wavelength conversion layer and the intersection of the perpendicular line with the surface of the wavelength conversion layer is measured to determine the thickness of the wavelength conversion layer. For example, when the wavelength conversion layer is provided with a predetermined width along the circumference of a disk-shaped support, the thickness of the wavelength conversion layer may be measured for an image of a cross section that passes through the center of the disk, is perpendicular to the support, and includes the predetermined width of the wavelength conversion layer as the full width. The cross-sectional area of ​​the wavelength conversion layer is calculated by multiplying the length of the full width of the wavelength conversion layer by the thickness of the wavelength conversion layer.

[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. 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 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] support The support may be a light-transmitting member containing a light-transmitting inorganic material such as glass or alumina. By using a light-transmitting member as the support, light incident on the wavelength conversion member can be wavelength-converted and emitted to the opposite side of the incident surface. At least one of the main surface on which the wavelength conversion layer of the light-transmitting member 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.

[0042] The support may be a metal member containing a metal material such as aluminum or copper. By using a metal member as the support, the light incident on the wavelength conversion member can be wavelength converted and emitted to the same side as the incident surface. Furthermore, the heat dissipation from the phosphor is improved, so that the luminous efficiency of the phosphor can be improved. The thickness of the support is not particularly limited and may be appropriately selected depending on the purpose, etc.

[0043] Method for manufacturing wavelength conversion member A method for producing the wavelength conversion member will be described below. The wavelength conversion member is produced, for example, by a production method including disposing a wavelength conversion layer including a phosphor layer on one main surface of a support.

[0044] The wavelength conversion layer may be formed on one main surface of the support by, for example, a printing method. The method of forming the wavelength conversion layer is not limited to the printing method, and the printing method and other known forming methods such as compression molding, phosphor electrodeposition, and adhesion of a phosphor sheet, or combinations of these forming methods can be appropriately used. When the wavelength conversion layer is formed by the printing method, the thickness of the wavelength conversion layer is set to the above-mentioned range in consideration of the suppression of uneven emission of the wavelength conversion member and the workability during printing.

[0045] Printing method A phosphor paste containing a phosphor and a binder is placed on the surface of the support. The phosphor may be the first phosphor described above. The binder may be an inorganic binder such as a resin, such as a silicone resin, an epoxy resin, a phenol resin, or a polyimide resin, or glass. The phosphor paste may contain a filler as necessary. The filler may be at least one selected from the group consisting of silica, titanium oxide, barium titanate, aluminum oxide, and silicon oxide. The phosphor paste is placed, for example, by moving a squeegee so that the phosphor paste passes through a screen plate placed on the support, and placing a predetermined thickness of phosphor paste on the support. This allows the phosphor paste to be placed with a substantially uniform thickness.

[0046] Then, when the desired distribution of phosphors is obtained in the phosphor paste, the binder of the phosphor paste is cured to form the wavelength conversion layer. The binder may be cured by an appropriate method such as drying, heating, or ultraviolet irradiation depending on the type of binder.

[0047] The wavelength conversion member can be manufactured by the above-mentioned method. An example of the obtained wavelength conversion member is shown in FIG. 1A and FIG. 1B. FIG. 1A is a schematic plan view of the wavelength conversion member 50 seen from the main surface side, and FIG. 1B is a schematic plan view of the wavelength conversion member 50 seen from the side surface side and a partially enlarged view thereof. As shown in FIG. 1A, the wavelength conversion layer 52 is disposed along the circumference of a disk-shaped support 54. Also, as shown in FIG. 1B, the wavelength conversion layer 52 is disposed on one of the main surfaces of the support 54 by laminating a phosphor layer 80 containing a phosphor 70 and a light transmission layer 82 containing a resin 76 in this order.

[0048] Light-emitting device The light emitting device includes a light emitting element and a wavelength conversion member including a phosphor excited by the light emitting element. The light emitting element has an emission peak wavelength within a wavelength range of, for example, 350 nm to 500 nm. The phosphor layer constituting the wavelength conversion member includes a first phosphor. The first phosphor may have a composition represented by, for example, formula (1). The phosphor layer has a thickness of 5 μm to 155 μm.

[0049] The light emitting device includes a wavelength conversion member including a first phosphor having a specific composition and a phosphor layer having a specific thickness, and thus has excellent luminous intensity of output light. In addition, the light emitting device can exhibit luminous characteristics with excellent linearity according to the output of the light emitting element constituting the light emitting device, and has excellent luminous characteristics at high output. Details of the wavelength conversion member constituting the light emitting device are as described above.

[0050] Light emitting element The emission peak wavelength of the light-emitting element may be within a wavelength range of 350 nm to 500 nm, preferably within a wavelength range of 380 nm to 470 nm, or within a wavelength range of 400 nm to 460 nm. By using a light-emitting element having an emission peak wavelength within this wavelength range as an excitation light source, it is possible to configure a light-emitting device that emits a mixed color light of the light from the light-emitting element and the fluorescence from the phosphor. Furthermore, a part of the light emitted from the light-emitting element can be effectively used as a part of the light emitted to the outside from the light-emitting device, so that a light-emitting device with high luminous efficiency can be obtained.

[0051] The half-width of the emission spectrum of the light-emitting element may be, for example, 30 nm or less. As the light-emitting element, it is preferable to use, for example, a semiconductor light-emitting element using a nitride-based semiconductor. By using a semiconductor light-emitting element as an excitation light source, it is possible to obtain a stable light-emitting device that is highly efficient, has high linearity of output relative to input, and is resistant to mechanical shock. The light-emitting element may be a light-emitting diode (LED) or a laser diode (LD). Furthermore, the light-emitting element may be used alone or in combination of two or more types.

[0052] The output of the light emitting element is, for example, 0.5 W / mm as the optical power density incident on 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 When the output of the light emitting element is within the above range, the wavelength conversion member has better linearity according to the output of the light emitting element.

[0053] Here, an example of the configuration of the light emitting device will be described with reference to the drawings. FIG. 2 is a schematic diagram showing an example of the configuration of the light emitting device. The light emitting device 100 includes a light emitting element 10, an incident optical system 20, and a wavelength conversion member 50. The wavelength conversion member 50 includes a support 54 and a wavelength conversion layer 52 that is disposed on the support 54 and includes a phosphor layer 80 containing phosphor 70 and a light transmission layer 82 containing a resin 76. The light emitted from the light emitting element 10 passes through the incident optical system 20, enters the wavelength conversion member 50 from the support 54 side, passes through the phosphor layer 80 containing phosphor 70, and at least a part of the incident light is wavelength converted by the phosphor 70. Alternatively, both the wavelength converted light and the remaining part of the incident light that has not been wavelength converted are emitted from the wavelength conversion member 50. In this case, the light emitted from the light emitting device is a mixed light of the light from the light emitting element 10 and the wavelength converted light.

[0054] FIG. 3 is a schematic diagram showing an example of the configuration of a light emitting device. The light emitting device 110 includes a light emitting element 10, an incident optical system 20, and a wavelength conversion member 50. The wavelength conversion member 50 includes a support 54 and a wavelength conversion layer 52 arranged on the support 54, in which a phosphor layer 80 containing a first phosphor 70 and a light transmission layer 82 containing a resin 76 are laminated in this order. The light emitted from the light emitting element 10 passes through the incident optical system 20, enters the wavelength conversion member 50 from the wavelength conversion layer 52 side, passes through the wavelength conversion layer 52, and the reflected light is emitted from the wavelength conversion layer 52. At least a part of the light passing through the wavelength conversion layer 52 is wavelength converted by the phosphor 70. Alternatively, both the wavelength converted light and the remaining part of the incident light that has not been wavelength converted are emitted from the wavelength conversion member 50. In this case, the light emitted from the light emitting device 210 is a mixed light of the light from the light emitting element 10 and the wavelength converted light.

[0055] Projector light source device A light source device for a projector includes the light emitting device described above. By including a light emitting device that has excellent light emission characteristics at high output, a high output projector can be configured.

[0056] A light emitting device having a wavelength conversion member according to the present disclosure 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 for general lighting devices such as ceiling lights, special lighting devices such as spotlights, stadium lighting, and studio lighting, vehicle lighting devices such as headlamps, projection devices such as head-up displays, endoscope lights, imaging devices such as digital cameras, mobile phones, and smartphones, monitors for personal computers (PCs), notebook personal computers, televisions, personal digital assistants (PDX), smartphones, tablet PCs, liquid crystal display devices such as mobile phones, and the like. EXAMPLES

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0058] Phosphors 1 to 4 are La p Ce q Y r Si6N s Four types of nitride phosphors having compositions represented by the following formula were prepared. The chromaticity (x, y) of the prepared phosphors was measured using a quantum efficiency measurement system (QE-2000 manufactured by Otsuka Electronics Co., Ltd.). In addition, the luminous intensity (ENG) of each phosphor was determined as a relative ENG (%) with the luminous intensity of phosphor 1 set at 100%. The median particle size (Dm) was measured using a laser diffraction particle size distribution measurement device (MASTER SIZER 3000 manufactured by MALVERN). The median particle size of the nitride phosphor is the particle size (Dm: median diameter) at which the volume cumulative frequency from the small particle size side in the particle size distribution reaches 50%.

[0059] [Table 1]

[0060] Example 1 A phosphor paste was prepared by mixing 100 parts by mass of silicone resin, which was a binder, and 135 parts by mass of phosphor 1. A metal member made of aluminum was used as the support, which was plate-like and disk-shaped when viewed from the main surface side. A phosphor paste was printed on one main surface of the support in a circular shape with a predetermined width along the circumference of the metal member to form a wavelength conversion layer. As a result, the desired wavelength conversion member was obtained.

[0061] The thicknesses of the phosphor layer, the light transmission layer, and the wavelength conversion layer were measured as follows. An image of a cross section passing through the center of the disk-shaped support and perpendicular to the support was obtained, in which a predetermined width of the phosphor layer could be observed as the full width. In the image of the cross section, a perpendicular line to the surface of the support was set at a position halfway across the full width of the phosphor layer. The distance between the intersection of the interface of the support and the phosphor layer with the perpendicular line and the intersection of the interface of the phosphor layer and the light transmission layer with the perpendicular line was measured to determine the thickness of the phosphor layer. The distance between the intersection of the interface of the support and the phosphor layer with the perpendicular line and the intersection of the perpendicular line with the surface of the wavelength conversion layer was measured to determine the thickness of the wavelength conversion layer. The thickness of the light transmission layer was determined by subtracting the thickness of the phosphor layer from the thickness of the wavelength conversion layer.

[0062] Examples 2 to 15, Comparative Example 1 A wavelength conversion member was obtained in the same manner as in Example 1, except that the type and amount of phosphor added were changed as shown in Table 2, and the amount of phosphor paste placed was changed so that the thickness of the phosphor layer was as shown in Table 2 below.

[0063] [Table 2]

[0064] The obtained wavelength conversion member is shown in schematic form in Fig. 1A and Fig. 1B. Fig. 1A is a schematic plan view of wavelength conversion member 50 as viewed from the main surface side, and Fig. 1B is a schematic plan view of wavelength conversion member 50 as viewed from the side surface side and a partially enlarged view thereof. As shown in Fig. 1A, wavelength conversion layer 52 is disposed in an annular shape with a predetermined width along the circumference of disk-shaped support 54. Also, as shown in Fig. 1B, wavelength conversion layer 52 composed of phosphor layer 80 containing phosphor 70 and a light transmitting layer containing resin 76 is disposed on one of the main surfaces of support 54.

[0065] The emission intensity of the wavelength conversion member was measured as follows. A disk-shaped wavelength conversion member was fixed to a driving device, and the emission characteristics were measured while rotating at a rotation speed of 7200 rpm. A laser diode (LD) with an emission peak wavelength of 455 nm was prepared as an excitation light source for the wavelength conversion member, and the output density (W / mm 2 ) was changed, and the emission intensity of the emitted light from the wavelength conversion member at each output density was measured in the range of 470 nm or more and 800 nm or less. The emission intensity is shown as a relative Po (%) with the emission intensity for each output density of the laser diode in Comparative Example 1 as the reference (100.0%). FIG. 4 also shows the change in emission intensity (relative Po (%)) of the emitted light from the wavelength conversion member with respect to the change in output density of the laser diode for the wavelength conversion members of Examples 1 and 4 and Comparative Example 1. FIG. 5 also shows the change in emission intensity of the emitted light from the wavelength conversion member with respect to the change in output density of the laser diode for the wavelength conversion members including phosphors 1, 2, and 3, which have similar compositions, and the wavelength conversion member including phosphor 4, at an output density of the laser diode (LD) of 132 W / mm 2 The change in relative Po (%) versus phosphor layer thickness is shown.

[0066] [Table 3]

[0067] As shown in Table 3, in the examples in which the thickness of the phosphor layer is smaller than that of Comparative Example 1, the relative Po is larger at each measured output. Also, as shown in FIG. 4, by using the wavelength conversion members according to Examples 1 and 4, the luminous intensity of the emitted light increases according to the change in the output density of the laser diode, and luminous characteristics with excellent linearity are shown. As shown in FIG. 5, it is found that the thinner the phosphor layer of the wavelength conversion member is, the higher the luminous intensity of the output light is.

[0068] For representative wavelength conversion members obtained above, the ratio of the sum of the cross-sectional areas of phosphor particles in the cross section of the wavelength conversion layer to the cross-sectional area of ​​the wavelength conversion layer (cross-sectional ratio) was evaluated as follows. The results are shown in Table 4.

[0069] Cross-sectional ratio evaluation Cross-sectional SEM images of the wavelength conversion layer obtained using a scanning electron microscope (SEM) were 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 images were binarized. The cross-sectional areas of each binarized phosphor were added up to calculate the total cross-sectional area of ​​the phosphors, and this was divided by the cross-sectional area of ​​the wavelength conversion layer to calculate the cross-sectional ratio.

[0070] [Table 4]

[0071] Examples 16 to 20 A wavelength conversion member was obtained in the same manner as in Example 1, except that phosphor 1 was used, the amount of phosphor added was changed as shown in Table 4, and the amount of phosphor paste placed was changed so that the thickness of the phosphor layer was as shown in Table 5 below.

[0072] The cross-sectional ratio of the wavelength conversion member obtained above was evaluated in the same manner as above. The results are shown in Table 5.

[0073] [Table 5]

[0074] The emission intensity was measured in the same manner as described above for the wavelength conversion members obtained in Examples 16 to 21. The emission intensity was shown as a relative Po (%) with the emission intensity for each output density of the laser diode in Example 17 as the reference (100.0%).

[0075] [Table 6]

[0076] As shown in Table 5, when Examples 16 and 17 are compared with Examples 18 to 20, it is found that Examples 18 to 20, which have a smaller cross-sectional ratio, have a larger relative Po at each measured output than Examples 16 and 17. From this, it is considered that when the thickness of the phosphor layer is equal to or less than a predetermined value and the cross-sectional ratio is small, the relative Po at each measured output is larger.

[0077] From the above results, it is considered that by reducing the amount of phosphor in the wavelength conversion layer, the effect of heat can be reduced and the luminescence characteristics can be maintained even under high output conditions. In general, in phosphors, electrons in the ground state transition to an excited state due to the light energy from the light source, and when returning to the ground state, excess energy is released as light. At that time, 100% of the light energy from the light source is rarely converted into light, and from this excited state, part of the energy is converted into heat and released. In other words, the more conversion to heat occurs, the greater the amount of heat generated in the wavelength conversion layer. Thus, since phosphors can be not only a light source but also a heat source, if more phosphors than necessary are contained in the wavelength conversion layer, there is a concern that the luminescence intensity will decrease due to heat.

[0078] From the evaluation results of Examples 1 to 15, by reducing the thickness of the phosphor layer, the influence of heat from the phosphor is reduced, and a good relative Po can be maintained even when the light source is in a high output condition. Also, from the evaluation results of Examples 16 to 20, a larger relative Po can be achieved by reducing not only the thickness of the phosphor layer but also the cross-sectional ratio. The reduction in the cross-sectional ratio, for example, reduces the density of the phosphor particles in the wavelength conversion layer. For example, in Examples 18 to 20, which have a lower cross-sectional ratio than Examples 16 and 17, a larger relative Po can be achieved. From the above, it is considered that a larger relative Po can be achieved by reducing the thickness of the phosphor layer, reducing the cross-sectional ratio, or considering both.

[0079] The thickness of the phosphor layer is required to be set so that it is efficiently excited by the light from the excitation light source. In addition, since light emission due to self-absorption between particles from the light emitted by the phosphor excited by the excitation light source is also considered, a certain phosphor layer thickness is required. However, as the thickness of the phosphor layer increases, it becomes more susceptible to the influence of heat emitted from the excitation light source. In particular, in laser diodes and light-emitting diodes used at high power, it is necessary to effectively dissipate heat from the wavelength conversion member. If a binder such as silicone resin is used to form the phosphor layer, the heat dissipation of the phosphor layer may be reduced. In that case, it is thought that the phosphor is affected by heat and the luminous efficiency of the phosphor decreases. In addition, since part of the excited energy of the phosphor is converted into heat, the phosphor itself also acts as a heat source. Therefore, it is thought that a phosphor layer having a minimum thickness that efficiently converts the wavelength of the excitation light is ideal. By considering these factors and making the wavelength conversion member of this embodiment, it is thought that the wavelength conversion member of this embodiment can sufficiently absorb the excitation light and reduce the influence of heat, thereby providing a wavelength conversion member with a greater luminous intensity of the output light. [Industrial Applicability]

[0080] The wavelength conversion member or light emitting device of the present disclosure can be used as a wavelength conversion member or light emitting device provided in a light source in, for example, general lighting devices such as ceiling lights, special lighting devices such as spotlights, stadium lighting, and studio lighting, vehicle lighting devices such as headlamps, projection devices such as projectors and head-up displays, endoscope lights, imaging devices such as digital cameras, mobile phones, and smartphones, monitors for personal computers (PCs), notebook personal computers, televisions, personal digital assistants (PDXs), smartphones, tablet PCs, liquid crystal display devices such as mobile phones, and the like. [Explanation of symbols]

[0081] 10: light emitting element, 50: wavelength conversion member, 52: wavelength conversion layer, 54: support, 70: phosphor, 80: phosphor layer, 82: light transmitting layer, 100, 110: light emitting device.

Claims

1. A wavelength conversion layer is provided on the support and has a phosphor layer including a phosphor having a composition represented by the following formula (1), The thickness of the phosphor layer is 40 μm or more and 155 μm or less, A wavelength conversion member, in a cross section perpendicular to a surface on which the wavelength conversion layer is placed on the support, the ratio of the sum of the particle cross-sectional areas of the phosphor particles to the cross-sectional area of ​​the wavelength conversion layer is 10% or more and 30% or less. L ｐ Yes ｑ M １ ｒ Yes ６ N ｓ (1) (In the above formula (1), M １ represents at least one rare earth element other than La and Ce, M １ the total molar content of Y, Gd and Lu in the composition is 90% or more, and p, q, r and s satisfy the following conditions: 2.7≦p+q+r≦3.3, 0≦r≦1.2, 10≦s≦12, and 0<q≦1.

2.

2. 2. The wavelength conversion member according to claim 1, wherein the phosphor layer has a thickness of 40 μm or more and 75 μm or less.

3. 3. The wavelength conversion member according to claim 1, wherein a ratio of a total particle cross-sectional area of ​​the phosphor to a cross-sectional area of ​​the wavelength conversion layer is 12% or more and 25% or less.

4. 4. The wavelength conversion member according to claim 1, wherein the median particle diameter of the phosphor is 5 μm or more and 40 μm or less.

5. In the formula (1), the M １ The wavelength conversion member according to claim 1 , wherein the molar content of Y in the wavelength conversion member is 90% or more.

6. A light emitting device comprising: the wavelength conversion member according to claim 1 ; and a light emitting element having an emission peak wavelength in a wavelength range of 350 nm or more and 500 nm or less.

7. The light emitting device according to claim 6 , wherein the light emitting element comprises a laser diode.

Images