Wavelength conversion member, method for manufacturing the same, and light-emitting device

Abstract

The present invention provides a wavelength conversion member that enables the precise acquisition of both desired chromaticity and thickness. [Solution] A wavelength conversion member 1 comprises a first wavelength conversion layer 10 including a first inorganic matrix 11 and a first inorganic phosphor 12 dispersed in the first inorganic matrix 11, and a second wavelength conversion layer 20 provided on the main surface 10a of the first wavelength conversion layer 10 and including a second inorganic matrix 21 and a second inorganic phosphor 22 dispersed in the second inorganic matrix 21, wherein the first inorganic phosphor 12 and the second inorganic phosphor 22 are composed of the same type of inorganic phosphor, and the volume concentration of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 is twice or more the volume concentration of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20.

Description

[Technical Field]

[0001] The present invention relates to a wavelength conversion member, a method for manufacturing the wavelength conversion member, and a light-emitting device using the wavelength conversion member. [Background technology]

[0002] Conventionally, light-emitting devices using light-emitting elements such as light-emitting diodes (LEDs) and laser diodes (LDs) are widely known. As an example of a light-emitting device, a device is known that utilizes composite light, which is the combination of excitation light emitted from a light source and passing through a wavelength conversion member, and fluorescence emitted from a phosphor contained in the wavelength conversion member. The wavelength conversion member that constitutes such a light-emitting device is manufactured, for example, by polishing a glass matrix in which an inorganic phosphor is dispersed and reducing its thickness.

[0003] Patent Document 1 discloses a wavelength conversion member comprising a glass matrix and phosphor particles arranged within the glass matrix. The wavelength conversion member of Patent Document 1 has a region in which a density gradient is provided such that the density of phosphor particles decreases from the first main surface side to the second main surface side of the wavelength conversion member. Patent Document 1 states that by having a region in which such a density gradient is provided in the wavelength conversion member, the chromaticity can be adjusted easily and with high precision. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-22096 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, even with the wavelength conversion member described in Patent Document 1, it can be difficult to accurately adjust both chromaticity and thickness. This tendency was particularly pronounced when the wavelength conversion member was designed to be thin.

[0006] The object of the present invention is to provide a wavelength conversion member, a method for manufacturing the wavelength conversion member, and a light-emitting device using the wavelength conversion member, which enable the acquisition of both desired chromaticity and thickness with high precision. [Means for solving the problem]

[0007] The following describes a wavelength conversion member that solves the above problems, a method for manufacturing the wavelength conversion member, and various embodiments of a light-emitting device using the wavelength conversion member.

[0008] A wavelength conversion member according to embodiment 1 of the present invention comprises a first wavelength conversion layer including a first inorganic matrix and a first inorganic phosphor dispersed in the first inorganic matrix, and a second wavelength conversion layer provided on the main surface of the first wavelength conversion layer and including a second inorganic matrix and a second inorganic phosphor dispersed in the second inorganic matrix, wherein the first inorganic phosphor and the second inorganic phosphor are composed of the same type of inorganic phosphor, and the volume concentration of the first inorganic phosphor contained in the first wavelength conversion layer is at least twice the volume concentration of the second inorganic phosphor contained in the second wavelength conversion layer.

[0009] In the wavelength conversion member according to Embodiment 2, it is preferable that in Embodiment 1, the first wavelength conversion layer contains one type of the first inorganic phosphor, and the second wavelength conversion layer contains one type of the second inorganic phosphor.

[0010] In the wavelength conversion member according to Embodiment 3, in Embodiment 1 or Embodiment 2, it is preferable that the absolute value of the difference between the average particle diameter of the first inorganic phosphor and the average particle diameter of the second inorganic phosphor is 5 μm or less.

[0011] In the wavelength conversion member according to Aspect 4, in any one of Aspects 1 to 3, it is preferable that the first inorganic matrix and the second inorganic matrix are each a glass matrix.

[0012] In the wavelength conversion member according to Aspect 5, in any one of Aspects 1 to 4, it is preferable that the thickness of the wavelength conversion member is 0.02 mm or more and 0.50 mm or less.

[0013] In the wavelength conversion member according to Aspect 6, in any one of Aspects 1 to 5, the ratio (first wavelength conversion layer / second wavelength conversion layer) of the thickness of the first wavelength conversion layer to the thickness of the second wavelength conversion layer is preferably 0.2 or more and 5 or less.

[0014] The method for manufacturing a wavelength conversion member according to Aspect 7 of the present invention is a method for manufacturing a wavelength conversion member according to any one of Aspects 1 to 6, and includes a step of applying a slurry containing inorganic particles to be the first inorganic matrix and inorganic phosphor particles to be the first inorganic phosphor on a support substrate to form a first green sheet; a step of applying a slurry containing inorganic particles to be the second inorganic matrix and inorganic phosphor particles to be the second inorganic phosphor on a support substrate to form a second green sheet; and a step of producing a green sheet laminate by laminating the second green sheet on the main surface of the first green sheet, and firing the green sheet laminate.

[0015] The light-emitting device according to Aspect 8 of the present invention includes a wavelength conversion member according to any one of Aspects 1 to 6, and a light source that emits excitation light to the wavelength conversion member.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a wavelength conversion member, a method for manufacturing the wavelength conversion member, and a light-emitting device using the wavelength conversion member that can accurately obtain both a desired chromaticity and thickness. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic cross-sectional view showing a wavelength conversion member according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing a light-emitting device according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic cross-sectional view showing a modified example of a light-emitting device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0018] Preferred embodiments are described below. However, the following embodiments are merely illustrative, and the present invention is not limited to these embodiments. In addition, in each drawing, components having substantially the same function may be referred to by the same reference numerals.

[0019] [Wavelength conversion component] Figure 1 is a schematic cross-sectional view showing a wavelength conversion member according to one embodiment of the present invention.

[0020] As shown in Figure 1, the wavelength conversion member 1 has a first main surface 1a and a second main surface 1b facing each other. In this embodiment, the first main surface 1a of the wavelength conversion member 1 is the light incident surface on which the excitation light A emitted from the light source 2 enters the wavelength conversion member 1. The second main surface 1b of the wavelength conversion member 1 is the light emission surface on which the fluorescence B is emitted from the wavelength conversion member 1.

[0021] In this embodiment, the wavelength conversion member 1 has a rectangular plate shape. However, the shape of the wavelength conversion member 1 is not particularly limited, and for example, it may have a disc shape or a tapered shape. The first main surface 1a of the wavelength conversion member 1 may be the light incident surface and does not necessarily have to be planar. The second main surface 1b of the wavelength conversion member 1 may be the light emission surface and does not necessarily have to be planar.

[0022] The wavelength conversion member 1 comprises a first wavelength conversion layer 10 and a second wavelength conversion layer 20. The first wavelength conversion layer 10 is provided on the first main surface 1a side, which is the light incident surface of the wavelength conversion member 1. The second wavelength conversion layer 20 is provided on the second main surface 1b side, which is the light emission surface of the wavelength conversion member 1.

[0023] The first wavelength conversion layer 10 includes a first inorganic matrix 11 and a first inorganic phosphor 12. In the first wavelength conversion layer 10, the first inorganic phosphor 12 is dispersed in the first inorganic matrix 11.

[0024] A second wavelength conversion layer 20 is provided on the main surface 10a of the first wavelength conversion layer 10. The second wavelength conversion layer 20 includes a second inorganic matrix 21 and a second inorganic phosphor 22. In the second wavelength conversion layer 20, the second inorganic phosphor 22 is dispersed in the second inorganic matrix 21.

[0025] The first inorganic phosphor 12 contained in the first wavelength conversion layer 10 and the second inorganic phosphor 22 contained in the second wavelength conversion layer 20 are composed of the same type of inorganic phosphor. In this embodiment, one type of first inorganic phosphor 12 and one type of second inorganic phosphor 22 are used. However, in the present invention, multiple types of first inorganic phosphors 12 and multiple types of second inorganic phosphors 22 may be used, in which case it is desirable that all first inorganic phosphors 12 and all second inorganic phosphors 22 are of the same type of phosphor.

[0026] In the wavelength conversion member 1, the volume concentration of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 is at least twice the volume concentration of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20. Furthermore, as described above, if multiple types of the first inorganic phosphor 12 and multiple types of the second inorganic phosphor 22 are used, it is sufficient that the sum of the volume concentrations of all the first inorganic phosphors 12 contained in the first wavelength conversion layer 10 is at least twice the sum of the volume concentrations of all the second inorganic phosphors 22 contained in the second wavelength conversion layer 20.

[0027] As shown in Figure 1, in the wavelength conversion member 1, excitation light A emitted from the light source 2 enters the wavelength conversion member 1 from the first main surface 1a side. The excitation light A that enters the wavelength conversion member 1 irradiates the first inorganic phosphor 12 and the second inorganic phosphor 22 contained within the wavelength conversion member 1. The excitation light A irradiated onto the first inorganic phosphor 12 and the second inorganic phosphor 22 is converted to a different wavelength by the first inorganic phosphor 12 and the second inorganic phosphor 22, and is emitted from the second main surface 1b side of the wavelength conversion member 1 as fluorescence B having the emission peak wavelength of the first inorganic phosphor 12 and the second inorganic phosphor 22. The light emitted from the second main surface 1b side of the wavelength conversion member 1 may be the combined light of excitation light A and fluorescence B, or it may be fluorescence B itself.

[0028] Since the wavelength conversion member 1 of this embodiment has the above configuration, it is possible to obtain both the desired chromaticity and thickness with high precision.

[0029] Conventionally, when manufacturing wavelength conversion components, the thickness and chromaticity of the resulting component were sometimes adjusted by polishing a glass matrix, for example, a glass base material in which an inorganic phosphor is dispersed in a glass matrix, to reduce its thickness. However, since reducing the thickness of the glass base material also reduces the chromaticity, there was a problem in that it was difficult to bring both the thickness and chromaticity of the resulting wavelength conversion component close to the target values. This tendency was particularly pronounced when designing the wavelength conversion component to be thin. Furthermore, in the method of creating a density gradient from the first main surface side to the second main surface side of the wavelength conversion component, there was a problem in that it was difficult to accurately grasp the inorganic phosphor concentration in the wavelength conversion component, making it difficult to precisely adjust the chromaticity.

[0030] In contrast, in this embodiment, the wavelength conversion member 1 has a first inorganic phosphor 12 volume concentration in the first wavelength conversion layer 10 provided on one main surface side (the first main surface 1a side) that is more than twice the volume concentration of the second inorganic phosphor 22 in the second wavelength conversion layer 20 provided on the other main surface side (the second main surface 1b side). Therefore, if it is desired to change the chromaticity while minimizing the influence on the thickness of the wavelength conversion member 1, the chromaticity can be greatly adjusted by polishing the first wavelength conversion layer 10 side (the side with a high volume concentration of phosphor), which only slightly reduces the thickness. Furthermore, if it is desired to change the thickness while minimizing the influence of the wavelength conversion member 1 on the chromaticity, the thickness can be further reduced by polishing the second wavelength conversion layer 20 side (the side with a low volume concentration of phosphor), which only slightly changes the chromaticity.

[0031] Furthermore, in this embodiment, the volume concentrations of the inorganic phosphors contained in the first wavelength conversion layer 10 and the second wavelength conversion layer 20 can be set without deliberately providing a concentration gradient in the wavelength conversion member 1. Therefore, the volume concentrations of the inorganic phosphors in each layer constituting the wavelength conversion member 1 can be clearly determined. As a result, the chromaticity of the wavelength conversion member 1 can be adjusted with high precision. Thus, with the wavelength conversion member 1 of this embodiment, both the desired chromaticity and thickness can be obtained with high precision.

[0032] In this embodiment, the volume concentration of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 is at least twice the volume concentration of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20, preferably at least three times, more preferably at least five times, even more preferably at least eight times, and preferably 30 times or less. In this case, the desired chromaticity and thickness can be obtained with even greater precision in the wavelength conversion member 1. Furthermore, when the volume concentration of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 is 30 times or less the volume concentration of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20, warping and strength reduction caused by the difference in thermal conductivity due to the difference in the concentration of the first inorganic phosphor 12 and the second inorganic phosphor 22 can be prevented even more reliably.

[0033] The volume concentration of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 is preferably 10% by volume or more, more preferably 15% by volume or more, even more preferably 18% by volume or more, preferably 70% by volume or less, more preferably 50% by volume or less, and even more preferably 40% by volume or less. When the volume concentration of the first inorganic phosphor 12 is above the lower limit, the chromaticity can be adjusted even more significantly by only slightly reducing the thickness. When the volume concentration of the first inorganic phosphor 12 is below the upper limit, the amount of the first inorganic matrix 11 does not become too small, so the strength of the wavelength conversion member 1 can be maintained more reliably.

[0034] The volume concentration of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20 is preferably 0.1 volume% or more, more preferably 1 volume% or more, even more preferably 2 volume% or more, preferably 30 volume% or less, more preferably 20 volume% or less, and even more preferably 15 volume% or less. When the volume concentration of the second inorganic phosphor 22 is below the above upper limit, the thickness can be made even thinner by only slightly changing the chromaticity. When the concentration of the second inorganic phosphor 22 is above the above lower limit, it is possible to fine-tune the chromaticity by the wavelength conversion member 1.

[0035] In this embodiment, the absolute difference between the average particle diameter of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 and the average particle diameter of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20 is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less, and it is particularly preferable that the average particle diameters of the first inorganic phosphor 12 and the second inorganic phosphor 22 are the same. In this case, the chromaticity by the wavelength conversion member 1 can be adjusted with even greater precision, and the productivity of the wavelength conversion member 1 can be further increased. In this specification, the average particle diameter is the particle diameter D at which the cumulative frequency is 50 volume% in the volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer. 50 This refers to the following.

[0036] In this embodiment, the first inorganic matrix 11 and the second inorganic matrix 21 are glass matrices, and are composed of glass having the same composition. As in this embodiment, it is preferable that the first inorganic matrix 11 and the second inorganic matrix 21 are composed of materials having the same composition, but they may be composed of materials having different compositions. Furthermore, while it is preferable that the first inorganic matrix 11 and the second inorganic matrix 21 are composed of glass, they may also be composed of ceramics or glass ceramics, and are not particularly limited.

[0037] In this embodiment, the thickness T of the wavelength conversion member 1 is preferably 0.02 mm or more, more preferably 0.03 mm or more, even more preferably 0.05 mm or more, preferably 0.50 mm or less, more preferably 0.35 mm or less, and even more preferably 0.20 mm or less. When the thickness T of the wavelength conversion member 1 is greater than or equal to the lower limit, the emission intensity of the light emitted from the wavelength conversion member 1 can be further increased. Furthermore, when the thickness T of the wavelength conversion member 1 is less than or equal to the upper limit, the effects of the present invention can be more reliably demonstrated.

[0038] The ratio of the thickness T1 of the first wavelength conversion layer 10 to the thickness T2 of the second wavelength conversion layer 20 (first wavelength conversion layer 10 / second wavelength conversion layer 20) is preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.5 or more, preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. In this case, the desired chromaticity and thickness can be obtained with even greater precision in the wavelength conversion member 1.

[0039] In this embodiment, the first wavelength conversion layer 10, which has a high volume concentration of inorganic phosphor, is located on the light source 2 side. However, the second wavelength conversion layer 20, which has a low volume concentration of inorganic phosphor, may also be located on the light source 2 side, and is not particularly limited. However, when the wavelength conversion member 1 is provided in contact with the light source 2, it is preferable that the first wavelength conversion layer 10, which has a high volume concentration of inorganic phosphor, is located on the light source 2 side. In this case, even if heat is generated from the first wavelength conversion layer 10, which has a high volume concentration of inorganic phosphor, the heat can be diffused through the light source 2.

[0040] The wavelength conversion member 1 can be suitably used as a component of general lighting such as white LEDs, or special lighting (for example, projector light sources, automotive headlights, turn signals, and other automotive lighting).

[0041] The following provides a more detailed explanation of each material that makes up the wavelength conversion component 1.

[0042] inorganic matrix; The first inorganic matrix 11 and the second inorganic matrix 21 are preferably composed of the same material, but they may be composed of different materials. The inorganic matrices used in the first inorganic matrix 11 and the second inorganic matrix 21 will be described in detail below.

[0043] The inorganic matrix is ​​preferably transparent. The light transmittance of the inorganic matrix at wavelengths from 380 nm to 780 nm and a thickness of 0.5 mm is preferably 30% or more, more preferably 50% or more. The upper limit of the above light transmittance is not particularly limited, but in reality it is 100% or less.

[0044] The inorganic matrix can be composed of, for example, glass or ceramics. Examples of glass that constitute the inorganic matrix include borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, or tellurite glass. Examples of ceramics that constitute the inorganic matrix include Al2O3, MgO, or AlN. The inorganic matrix may also be composed of other materials such as glass ceramics.

[0045] When the inorganic matrix is ​​a glass matrix, it is preferable that the glass matrix is ​​a glass with a low alkali metal content. Specifically, the content of Li2O+Na2O+K2O in the glass matrix is ​​preferably 0% to 10%, more preferably 0% to 5%, and even more preferably 0% to 3%, in mole percent. In this case, it is possible to suppress the formation of colored centers that serve as absorption sources for excitation light A and fluorescence B in the glass matrix, and to suppress the decrease in the emission intensity of light emitted from the wavelength conversion member 1. Furthermore, in this case, it is also possible to suppress the deterioration of the glass matrix over time under high temperature and high humidity conditions.

[0046] The softening point of the glass matrix is ​​preferably 250°C to 1000°C, more preferably 300°C to 950°C, and even more preferably 500°C to 900°C.

[0047] The softening point of the glass matrix is ​​preferably 500°C or higher, more preferably 550°C or higher, even more preferably 600°C or higher, even more preferably 650°C or higher, even more preferably 700°C or higher, even more preferably 750°C or higher, particularly preferably 800°C or higher, and most preferably 820°C or higher. Examples of glass constituting such a glass matrix include borosilicate glass. When the softening point of the glass matrix is ​​above the above lower limit, the mechanical strength and chemical durability of the wavelength conversion member 1 can be further improved. In this case, the heat resistance of the glass matrix itself can be further improved, and the softening deformation of the glass matrix due to heat generated from the inorganic phosphor can be further suppressed.

[0048] Furthermore, the softening point of the glass matrix is ​​preferably 900°C or lower, more preferably 850°C or lower, even more preferably 840°C or lower, even more preferably 830°C or lower, even more preferably 820°C or lower, even more preferably 810°C or lower, even more preferably 800°C or lower, even more preferably 790°C or lower, even more preferably 780°C or lower, even more preferably 760°C or lower, even more preferably 750°C or lower, even more preferably 700°C or lower, even more preferably 650°C or lower, even more preferably 600°C or lower, even more preferably 550°C or lower, even more preferably 530°C or lower, even more preferably 500°C or lower, particularly preferably 480°C or lower, and most preferably 460°C or lower. Examples of glass constituting such a glass matrix include borosilicate glass, tin phosphate glass, bismuthate glass, or tellurite glass. When the softening point of the glass matrix is ​​below the above upper limit, the firing temperature during the manufacture of the wavelength conversion member 1 can be further reduced, thereby suppressing the manufacturing cost of the wavelength conversion member 1. Furthermore, in this case, the degradation of the inorganic phosphor due to the firing process during the manufacturing of the wavelength conversion member 1 is suppressed, which further suppresses the decrease in the emission intensity of the light emitted from the wavelength conversion member 1.

[0049] Inorganic phosphors; The first inorganic phosphor 12 and the second inorganic phosphor 22 are composed of the same type of inorganic phosphor. Hereinafter, the inorganic phosphor used for the first inorganic phosphor 12 and the second inorganic phosphor 22 will be described in detail.

[0050] The inorganic phosphor is not particularly limited as long as it emits fluorescence upon incidence of excitation light. Examples of the inorganic phosphor include oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, oxychloride phosphors, sulfide phosphors,oxysulfide phosphors, halide phosphors, chalcogenide phosphors, aluminate phosphors, halophosphate chloride phosphors, or garnet-based compound phosphors, etc. These inorganic phosphors may be used alone or in combination of two or more.

[0051] As the inorganic phosphor, phosphor particles coated with a coating material such as an oxide may be used. In this case, the activation of the movement of electrons, holes, or alkali ions in the inorganic matrix can be suppressed, and as a result, the formation of coloring centers can be suppressed. Also, in this case, the conduction of heat generated from the inorganic phosphor to the inorganic matrix can be suppressed.

[0052] [[ID=I2]]As the inorganic phosphor, a phosphor having an excitation band between wavelengths of 300 nm and 500 nm and an emission peak between wavelengths of 500 nm and 780 nm, particularly a phosphor that emits light in green (wavelength 500 nm to 540 nm), yellow (wavelength 540 nm to 595 nm), or red (wavelength 600 nm to 700 nm) can be preferably used.

[0053] Examples of the inorganic phosphor having an excitation band between wavelengths of 300 nm and 440 nm, which is an ultraviolet to near-ultraviolet wavelength range, and having a green emission peak include SrAl2O4:Eu 2+ , SrBaSiO4:Eu 2+ , Y3(Al,Gd)5O 12 :Ce 3+ , SrSiON:Eu 2+ , BaMgAl 10 O 17 :Eu 2+ ,Mn 2+ , Ba2MgSi2O7:Eu2+ Ba2SiO4:Eu 2+ Ba2Li2Si2O7:Eu 2+ BaAl2O4:Eu 2+ These are some examples.

[0054] As an inorganic phosphor having an excitation band in the blue wavelength range of 440 nm to 480 nm and a green emission peak, SrAl2O4:Eu 2+ Lu3Al5O 12 :Ce,SrBaSiO4:Eu 2+ Y3(Al,Gd)5O 12 :Ce 3+ SrSiON:Eu 2+ β-SiAlON:Eu 2+ These are some examples.

[0055] As an inorganic phosphor having an excitation band in the ultraviolet to near-ultraviolet wavelength range of 300 nm to 440 nm and a yellow emission peak, La3Si6N is an example. 11 :Ce 3+ These are some examples.

[0056] An inorganic phosphor having an excitation band in the blue wavelength range of 440 nm to 480 nm and a yellow emission peak is Y3(Al,Gd)5O 12 :Ce 3+ Lu3Al5O 12 :Ce,Sr2SiO4:Eu 2+ These are some examples.

[0057] An inorganic phosphor having an excitation band in the ultraviolet to near-ultraviolet wavelength range of 300 nm to 440 nm and exhibiting a red emission peak is MgSr3Si2O8:Eu 2+ ,Mn 2+ Ca2MgSi2O7:Eu 2+ ,Mn 2+ These are some examples.

[0058] As an inorganic phosphor having an excitation band in the blue wavelength range of 440 nm to 480 nm and a yellow to red, so-called amber emission peak, CaAlSiN3:Eu2+ (CASN), (Ca,Sr)AlSiN3:Eu 2+ (SCASN), CaSiN3:Eu 2+ (Ca,Sr)2Si5N8:Eu 2+ α-SiAlON:Eu 2+ Ba2Si5N8:Eu 2+ Examples include Ce-activated CALSON phosphors.

[0059] When the inorganic matrix is ​​a glass matrix, the refractive index of the inorganic phosphor is often higher than that of the glass matrix. In the wavelength conversion member 1, if the refractive index difference between the inorganic phosphor and the glass matrix is ​​large, the excitation light A is more likely to be scattered at the interface between the inorganic phosphor and the glass matrix. As a result, the irradiation efficiency of the excitation light A to the inorganic phosphor increases, and the luminescence efficiency of the inorganic phosphor tends to improve. However, if the refractive index difference between the inorganic phosphor and the glass matrix is ​​too large, the scattering of the excitation light becomes excessive, resulting in scattering loss and conversely, a decrease in the luminescence efficiency of the inorganic phosphor tends to occur.

[0060] Considering these factors, the refractive index difference between the inorganic phosphor and the glass matrix is ​​preferably 0.001 to 0.6. Furthermore, the refractive index (nd) of the glass matrix is ​​preferably 1.45 to 1.8, more preferably 1.47 to 1.75, and even more preferably 1.48 to 1.7.

[0061] The average particle size of the inorganic phosphor is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. When the average particle size of the inorganic phosphor is greater than or equal to the lower limit, the emission intensity of the light emitted from the wavelength conversion member 1 can be further increased. Also, when the average particle size of the inorganic phosphor is less than or equal to the upper limit, the dispersibility of the inorganic phosphor in the inorganic matrix can be further increased, and the emission color of the light emitted from the wavelength conversion member 1 can be made even more uniform.

[0062] Other additives; The first wavelength conversion layer 10 and the second wavelength conversion layer 20 may contain additives other than inorganic phosphors. Examples of these additives include light-diffusing materials such as alumina, silica, or magnesia. The content of each of these additives in the first wavelength conversion layer 10 and the second wavelength conversion layer 20 is not particularly limited as long as it does not hinder the effects of the present invention, but can be, for example, 5% by volume or less.

[0063] The following describes an example of a method for manufacturing the wavelength conversion member 1.

[0064] Method for manufacturing wavelength conversion components; In the method for manufacturing the wavelength conversion member 1, first, a first slurry is prepared containing inorganic particles that will form the first inorganic matrix 11 and inorganic phosphor particles that will form the first inorganic phosphor 12. The first slurry may also contain organic components such as a binder or solvent.

[0065] Next, a second slurry is prepared containing inorganic particles that will form a second inorganic matrix 21 and inorganic phosphor particles that will form a second inorganic phosphor 22. The second slurry may also contain organic components such as a binder or solvent.

[0066] The inorganic phosphor particles that form the first inorganic phosphor 12 and the inorganic phosphor particles that form the second inorganic phosphor 22 shall be of the same type. Furthermore, the volume concentration of inorganic phosphor particles contained in the first slurry shall be adjusted to be at least twice the volume concentration of inorganic phosphor particles contained in the second slurry. It is desirable that the inorganic particles that form the first inorganic matrix 11 and the inorganic particles that form the second inorganic matrix 21 be of the same type.

[0067] The volume concentration of inorganic phosphor particles contained in the first slurry is preferably adjusted to be at least twice the volume concentration of inorganic phosphor particles contained in the second slurry, more preferably at least three times, even more preferably at least five times, and preferably 30 times or less.

[0068] Next, the first green sheet is formed by applying the prepared first slurry onto the support substrate. A second green sheet is also formed by applying the prepared second slurry onto the support substrate. The first and second green sheets can be formed, for example, by applying the prepared slurry onto the support substrate and moving a doctor blade, positioned at a predetermined distance from the support substrate, relative to the slurry. As the support substrate, for example, a resin film such as polyethylene terephthalate can be used.

[0069] Next, the first green sheet and the second green sheet are heat-dried. Then, a green sheet laminate is made by laminating the second green sheet onto the main surface of the first green sheet. At this time, it is preferable to make the green sheet laminate by heat-pressing the second green sheet onto the main surface of the first green sheet.

[0070] Next, the prepared green sheet laminate is fired to obtain the wavelength conversion member 1. The firing temperature of the green sheet laminate is preferably within ±150°C of the softening point of the glass powder, and more preferably within ±100°C of the softening point of the glass powder, when the inorganic particles are glass powder. If the firing temperature of the green sheet laminate is too low, the glass powder will not flow sufficiently, and it will be difficult to obtain a dense sintered body. On the other hand, if the firing temperature of the green sheet laminate is too high, the inorganic phosphor particles may degrade due to heat, or foaming may occur due to the reaction between the inorganic phosphor particles and the glass powder, which may reduce the luminescence intensity and mechanical strength of the wavelength conversion member 1. Also, if the firing temperature of the green sheet laminate is too high, the inorganic phosphor particles may dissolve into the glass matrix, reducing the luminescence intensity of the wavelength conversion member 1, or the inorganic phosphor particles may diffuse into the glass matrix, causing the glass matrix to become discolored and reducing the luminescence intensity of the wavelength conversion member 1. The firing atmosphere for the green sheet laminate is preferably a reduced pressure atmosphere, and more preferably a vacuum atmosphere. However, the firing atmosphere for the green sheet laminate may be under atmospheric pressure or a nitrogen atmosphere. Furthermore, the firing time for the green sheet laminate can be, for example, 3 hours or more and 24 hours or less.

[0071] Furthermore, the obtained wavelength conversion member 1 may be used after adjusting its thickness and chromaticity by polishing at least one of its first main surface 1a and second main surface 1b. In particular, the obtained wavelength conversion member 1 has a volume concentration of the first inorganic phosphor 12 contained in the first wavelength conversion layer 10 provided on the first main surface 1a side that is at least twice the volume concentration of the second inorganic phosphor 22 contained in the second wavelength conversion layer 20 provided on the second main surface 1b side. Therefore, if it is desired to change the chromaticity while minimizing the impact on the thickness of the wavelength conversion member 1, polishing the first wavelength conversion layer 10 side (the side with a higher volume concentration of phosphor) will allow for a significant adjustment of the chromaticity by only slightly reducing the thickness. Alternatively, if it is desired to change the thickness while minimizing the impact on the chromaticity of the wavelength conversion member 1, polishing the second wavelength conversion layer 20 side (the side with a lower volume concentration of phosphor) will allow for an even thinner thickness by only slightly changing the chromaticity.

[0072] Examples of polishing methods for the wavelength conversion member 1 include lapping and mirror polishing. Lapping has the advantage of being faster than mirror polishing. On the other hand, mirror polishing has the advantage of producing a better surface finish than lapping. The polishing method for the wavelength conversion member 1 should be appropriately determined according to the application in which the wavelength conversion member 1 is used.

[0073] The surface roughness Ra of the first main surface 1a and the second main surface 1b of the wavelength conversion member 1 is preferably 0.5 μm or less, and more preferably 0.1 μm or less, respectively. Furthermore, the lower limit of the surface roughness Ra is not particularly limited, but is substantially 0.0001 μm or more. Note that surface roughness Ra refers to the arithmetic mean roughness Ra as defined in JIS B0601-2001.

[0074] Functional films such as reflective films, anti-reflective films, or filter films may be provided on the first main surface 1a and the second main surface 1b of the wavelength conversion member 1. These functional films can be, for example, conventionally known dielectric multilayer films.

[0075] [Light-emitting devices] Figure 2 is a schematic cross-sectional view showing a light-emitting device according to one embodiment of the present invention. As shown in Figure 2, the light-emitting device 31 comprises a wavelength conversion member 1 according to the above-described embodiment and a light source 2 that emits excitation light A to the wavelength conversion member 1. In the light-emitting device 31, the light source 2 is arranged so that the excitation light A is directly incident on the wavelength conversion member 1.

[0076] Figure 3 is a schematic cross-sectional view showing a modified example of a light-emitting device according to one embodiment of the present invention. As shown in Figure 3, in the light-emitting device 41, a light guide plate 42 is arranged between the light source 2 and the wavelength conversion member 1. The light source 2 is arranged so that the excitation light A is directly incident on the light guide plate 42. The excitation light A emitted from the light source 2 passes through the light guide plate 42 and is incident on the wavelength conversion member 1. Specifically, the excitation light A is incident from the end face of the light guide plate 42, exits from the main surface of the light guide plate 42, and is incident on the wavelength conversion member 1. A material with low absorption of excitation light A can be used as the light guide plate 42. In addition, the light guide plate 42 and the wavelength conversion member 1 may be joined together.

[0077] Since the light-emitting devices 31 and 41 are equipped with the wavelength conversion member 1 described above, light of a desired chromaticity can be efficiently extracted from the wavelength conversion member 1.

[0078] The present invention will be described in more detail below based on specific examples. The present invention is not limited in any way to the following examples, and can be implemented with appropriate modifications without changing its essence.

[0079] (Example 1) As inorganic particles for the first and second inorganic matrices, a glass powder (average particle size D) having a composition of SiO2 61.4%, B2O 35.3%, Al2O 33.6%, CaO 13.2%, BaO 12%, and ZnO 4.5% in molars is used. 50 YAG phosphor particles (average particle size D: 2 μm, softening point: 850°C) were prepared. In addition, as inorganic phosphor particles to be the first and second inorganic phosphors, YAG phosphor particles (average particle size D: 2 μm, softening point: 850°C) were prepared. 50A 25 μm (25 μm) was prepared. Thus, the same glass powder was used as the inorganic particles for the first and second inorganic matrices. In addition, the same YAG phosphor particles were used as the inorganic phosphor particles for the first and second inorganic phosphors.

[0080] Next, a binder resin (Oricox, manufactured by Kyoeisha Chemical Co., Ltd.), a plasticizer (dioctyl adipate), a dispersant (Floren G-700, manufactured by Kyoeisha Chemical Co., Ltd.), and an organic solvent (methyl ethyl ketone) were added to the prepared glass powder and inorganic phosphor particles and kneaded to obtain a first slurry. In the first slurry, the inorganic phosphor particles were added so that the volume concentration of the first inorganic phosphor in the formed first wavelength conversion layer was 30% by volume.

[0081] Next, a second slurry was obtained by adding a binder resin (Oricox, manufactured by Kyoeisha Chemical Co., Ltd.), a plasticizer (dioctyl adipate), a dispersant (Floren G-700, manufactured by Kyoeisha Chemical Co., Ltd.), and an organic solvent (methyl ethyl ketone) to the prepared glass powder and inorganic phosphor particles and kneading them together. In the second slurry, the inorganic phosphor particles were added so that the volume concentration of the second inorganic phosphor in the formed second wavelength conversion layer was 3% by volume.

[0082] Next, the obtained first slurry was formed into a sheet using the doctor blade method and dried at room temperature to obtain the first green sheet. Furthermore, the obtained second slurry was formed into a sheet using the doctor blade method and dried at room temperature to obtain the second green sheet.

[0083] Next, a green sheet laminate was fabricated by heat-pressing a second green sheet onto the main surface of the obtained first green sheet.

[0084] Next, the obtained green sheet laminate was degreased in an electric furnace, and then vacuum-fired in a vacuum gas-purged furnace at 900°C (softening point of glass powder + 50°C) for 12 hours to obtain a wavelength conversion member in which a second wavelength conversion layer was provided on top of a first wavelength conversion layer. The thickness of the obtained wavelength conversion member was 0.10 mm, the thickness of the first wavelength conversion layer was 0.05 mm, and the thickness of the second wavelength conversion layer was 0.05 mm.

[0085] (Example 2) A wavelength conversion member was obtained in the same manner as in Example 1, except that in the first slurry, inorganic phosphor particles were added so that the content of the first inorganic phosphor in the formed first wavelength conversion layer was 25% by volume, and in the second slurry, inorganic phosphor particles were added so that the content of the second inorganic phosphor in the formed second wavelength conversion layer was 5% by volume. The thickness of the obtained wavelength conversion member was 0.10 mm, the thickness of the first wavelength conversion layer was 0.05 mm, and the thickness of the second wavelength conversion layer was 0.05 mm.

[0086] (Example 3) A wavelength conversion member was obtained in the same manner as in Example 1, except that in the first slurry, inorganic phosphor particles were added so that the content of the first inorganic phosphor in the formed first wavelength conversion layer was 20% by volume, and in the second slurry, inorganic phosphor particles were added so that the content of the second inorganic phosphor in the formed second wavelength conversion layer was 10% by volume. The thickness of the obtained wavelength conversion member was 0.15 mm, the thickness of the first wavelength conversion layer was 0.10 mm, and the thickness of the second wavelength conversion layer was 0.05 mm.

[0087] (Comparative Example 1) A slurry was obtained by kneading glass powder and inorganic phosphor particles, prepared in the same manner as in Example 1, with a binder resin (Oricox, manufactured by Kyoeisha Chemical Co., Ltd.), a plasticizer (dioctyl adipate), a dispersant (Floren G-700, manufactured by Kyoeisha Chemical Co., Ltd.), and an organic solvent (methyl ethyl ketone). In the slurry, inorganic phosphor particles were added so that the inorganic phosphor content in the formed wavelength conversion member was 30% by volume.

[0088] Next, the obtained slurry was formed into a sheet using the doctor blade method and dried at room temperature to settle the inorganic phosphor particles, creating a concentration gradient of inorganic phosphor particles and obtaining a green sheet. Then, the obtained green sheet was degreased in an electric furnace, and vacuum firing was performed in a vacuum gas displacement furnace at 900°C (softening point of glass powder + 50°C) for 12 hours to obtain a wavelength conversion member. The thickness of the obtained wavelength conversion member was 0.10 mm.

[0089] [evaluation] (Evaluation of chromaticity and thickness accuracy) The wavelength conversion members obtained in Examples 1-3 and Comparative Example 1 were polished, and the accuracy of chromaticity and thickness relative to the target value was evaluated according to the following evaluation criteria.

[0090] <Evaluation Criteria> A... We were able to achieve the target values ​​for chromaticity and thickness. B…Although less accurate than A, it nearly achieved the target values ​​for chromaticity and thickness. C... Either the chromaticity or the thickness was significantly different from the target value.

[0091] (Evaluation of chromaticity variation) Ten wavelength conversion members were prepared according to Examples 1-3 and Comparative Example 1, and the chromaticity variation of the polished wavelength conversion members was evaluated using the following evaluation criteria.

[0092] <Evaluation Criteria> ○...Color variation within ±0.0050 ×...Color variation is greater than ±0.0050

[0093] The results are shown in Table 1 below. In Table 1, the ratio of the volume concentration of the first inorganic phosphor contained in the first wavelength conversion layer to the volume concentration of the second inorganic phosphor contained in the second wavelength conversion layer is referred to as the volume concentration ratio.

[0094] [Table 1] [Explanation of Symbols]

[0095] 1...Wavelength conversion component 1a...First main surface 1b...Second principal surface 2...Light source 10…First wavelength conversion layer 10a…main surface 11…The first inorganic matrix 12…First inorganic phosphor 20...Second wavelength conversion layer 21... The second inorganic matrix 22…Second inorganic phosphor 31, 41… Light-emitting devices 42...Light guide plate A...Excitation light B...Fluorescent

Claims

1. A first wavelength conversion layer comprising a first inorganic matrix and a first inorganic phosphor dispersed in the first inorganic matrix, A second wavelength conversion layer is provided on the main surface of the first wavelength conversion layer and includes a second inorganic matrix and a second inorganic phosphor dispersed in the second inorganic matrix, Equipped with, The first inorganic phosphor and the second inorganic phosphor are composed of the same type of inorganic phosphor. A wavelength conversion member in which the volume concentration of the first inorganic phosphor contained in the first wavelength conversion layer is twice or more the volume concentration of the second inorganic phosphor contained in the second wavelength conversion layer.

2. The first wavelength conversion layer contains one type of the first inorganic phosphor, The wavelength conversion member according to claim 1, wherein the second wavelength conversion layer contains one type of the second inorganic phosphor.

3. The wavelength conversion member according to claim 1 or 2, wherein the absolute value of the difference between the average particle diameter of the first inorganic phosphor and the average particle diameter of the second inorganic phosphor is 5 μm or less.

4. The wavelength conversion member according to claim 1 or 2, wherein the first inorganic matrix and the second inorganic matrix are each glass matrices.

5. The wavelength conversion member according to claim 1 or 2, wherein the thickness of the wavelength conversion member is 0.02 mm or more and 0.50 mm or less.

6. The wavelength conversion member according to claim 1 or 2, wherein the ratio of the thickness of the first wavelength conversion layer to the thickness of the second wavelength conversion layer (first wavelength conversion layer / second wavelength conversion layer) is 0.2 or more and 5 or less.

7. A method for manufacturing a wavelength conversion member according to claim 1 or 2, A step of forming a first green sheet by applying a slurry containing inorganic particles that form the first inorganic matrix and inorganic phosphor particles that form the first inorganic phosphor onto a support substrate, A step of forming a second green sheet by applying a slurry containing inorganic particles that form the second inorganic matrix and inorganic phosphor particles that form the second inorganic phosphor onto a support substrate, The process involves laminating the second green sheet onto the main surface of the first green sheet to produce a green sheet laminate, and then firing the green sheet laminate. A method for manufacturing a wavelength conversion member, comprising the above.

8. A wavelength conversion member according to claim 1 or 2, The wavelength conversion member is provided with a light source that emits excitation light, A light-emitting device comprising the above features.

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