Wavelength conversion member and light-emitting device

Abstract

To provide a wavelength conversion member which can effectively achieve higher light extraction efficiency.SOLUTION: A wavelength conversion member 1 disclosed herein comprises a tabular member 2 and a phosphor layer 3 provided on a main surface 2a of the tabular member 2, the phosphor layer 3 containing an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix. A parameter P represented by the following expression (1) is in a range of 1000 to 4500, inclusive: P=S0.5×A×T ...(1), where S(1 / cm) represents surface area per unit volume of the inorganic phosphor, A (vol.%) represents content of the inorganic phosphor in the phosphor layer 3, and T (μm) represents a thickness of the phosphor layer 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

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

[0004] By the way, as the wavelength conversion member, a member in which a phosphor layer is provided on the main surface of a plate-shaped member may be used. Such a wavelength conversion member can be formed, for example, by applying a slurry containing a phosphor to the main surface of a plate-shaped member and sintering it. Therefore, such a wavelength conversion member is being studied as a wavelength conversion member that can fill the phosphor at a high concentration while reducing the thickness of the phosphor layer and can increase the emission intensity of a light-emitting device. However, even with such a wavelength conversion member, depending on the configuration of the phosphor layer, the light extraction efficiency may not be sufficiently increased.

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

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

[0007] The wavelength conversion member according to aspect 1 of the present invention comprises a plate-shaped member and a phosphor layer provided on a main surface of the plate-shaped member, the phosphor layer including an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix, and is characterized in that a parameter P represented by the following formula (1) is 1000 or more and 4500 or less, where S (1 / cm) is a surface area per unit volume of the inorganic phosphor, A (volume %) is a content of the inorganic phosphor in the phosphor layer, and T (μm) is a thickness of the phosphor layer.

[0008] P=S 0.5 ×A×T…Formula (1)

[0009] The wavelength conversion member of aspect 2 is preferably the same as aspect 1, in which the surface area S per unit volume of the inorganic phosphor is 4000 (1 / cm) or more and 100000 (1 / cm) or less.

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

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

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

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

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

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

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

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

[0018] A method for manufacturing a wavelength conversion member according to aspect 11 of the present invention includes the steps of preparing a plate-like member and forming a phosphor layer on a main surface of the plate-like member, the phosphor layer including an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix. In the step of forming the phosphor layer, when the surface area per unit volume of the inorganic phosphor is S (1 / cm), the content of the inorganic phosphor in the phosphor layer is A (volume %), and the thickness of the phosphor layer is T (μm), S (1 / cm), A (volume %), and T (μm) are adjusted so that a parameter P represented by the following formula (1) is 1000 or more and 4500 or less.

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

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

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

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

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

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

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

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

[0027] The wavelength conversion member 1 of the present embodiment is characterized in that, when the surface area per unit volume of the inorganic phosphor 5 is S (1 / cm), the content of the inorganic phosphor 5 in the phosphor layer 3 is A (volume %), and the thickness of the phosphor layer 3 is T (μm), the parameter P represented by the following formula (1) is 1000 or more and 4500 or less. Note that in formula (1), the content A of the inorganic phosphor 5 is multiplied by the volume ratio of the content of the inorganic phosphor 5 to the entire material in the phosphor layer 3.

[0028] P=S 0.5 ×A×T…Formula (1)

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

[0030] Regarding this point, the present inventors have intensively studied and found that in a wavelength conversion member in which a phosphor layer is provided on the main surface of a plate-shaped member, the specific surface area of ​​the inorganic phosphor changes the interface area between the inorganic matrix such as glass and the inorganic phosphor, and the scattering factor of the phosphor layer changes significantly. For example, if an inorganic phosphor with a large specific surface area is packed at a high concentration to produce a thick phosphor layer, the scattering factor of the phosphor layer is large and light is difficult to transmit through the phosphor layer, so that the return light component of the fluorescence, which is wavelength-converted light, becomes large, and as a result, the light extraction efficiency on the exit side may not be sufficiently improved. In such a case, by reducing the thickness of the phosphor layer and reducing the scattering factor, it is possible to extract the fluorescence on the exit side with high efficiency.

[0031] Therefore, the present inventors focused on the surface area per unit volume S (1 / cm) of the inorganic phosphor 5, the content A (volume %) of the inorganic phosphor 5 in the phosphor layer 3, and the thickness T (μm) of the phosphor layer 3 constituting the wavelength conversion member 1, and found that when parameter P resulting from these is 1000 or more and 4500 or less, the light extraction efficiency of the wavelength conversion member 1 can be effectively increased.

[0032] In this embodiment, the parameter P represented by the above formula (1) is 1000 or more, preferably 1800 or more, more preferably 2000 or more, and is 4500 or less, preferably 4400 or less, more preferably 4300 or less. In this case, the light extraction efficiency in the wavelength conversion member 1 can be increased more effectively.

[0033] In this embodiment, the surface area S per unit volume of the inorganic phosphor 5 is not particularly limited, and may be 4000 (1 / cm) or more, 5000 (1 / cm) or more, or 6000 (1 / cm) or more, and may be 100,000 (1 / cm) or less, 90,000 (1 / cm) or less, or 80,000 (1 / cm) or less.

[0034] The surface area S per unit volume of the inorganic phosphor 5 affects the change in the interface area between the inorganic phosphor 5 and the inorganic matrix 4 in the phosphor layer 3, and is a factor for adjusting the scattering factor of the phosphor layer 3. When the surface area S per unit volume of the inorganic phosphor 5 is equal to or greater than the above lower limit, the interface area between the inorganic phosphor 5 and the inorganic matrix 4 can be made larger, and the scattering factor of the phosphor layer 3 can be made even larger. This allows the inorganic phosphor 5 in the phosphor layer 3 to irradiate excitation light more efficiently. When the surface area S per unit volume of the inorganic phosphor 5 is equal to or less than the above upper limit, the interface area between the inorganic phosphor 5 and the inorganic matrix 4 is not made too large, so that the scattering factor of the phosphor layer 3 is appropriately suppressed, and the fluorescence can be extracted more efficiently to the exit side. When the surface area S per unit volume of the inorganic phosphor 5 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0035] In this specification, the surface area S per unit volume of the inorganic phosphor 5 can be calculated from the product of the surface area per unit mass of the inorganic phosphor 5 and the density of the inorganic phosphor 5. The surface area per unit mass of the inorganic phosphor 5 is the BET specific surface area measured by a multipoint BET method using nitrogen as an adsorbate.

[0036] In this embodiment, the content A of the inorganic phosphor 5 in the phosphor layer 3 is preferably 20 vol.% or more, more preferably 30 vol.% or more, even more preferably 40 vol.% or more, and preferably 80 vol.% or less, more preferably 75 vol.% or less, even more preferably 70 vol.% or less, even more preferably 67 vol.% or less, and particularly preferably 64 vol.% or less.

[0037] When the content A of the inorganic phosphor 5 in the phosphor layer 3 is equal to or greater than the above lower limit, the luminescence intensity of the wavelength conversion member 1 can be further increased even when the thickness of the phosphor layer 3 is reduced. When the content A of the inorganic phosphor 5 in the phosphor layer 3 is equal to or less than the above upper limit, the thickness of the phosphor layer 3 does not need to be made too thin, and the proportion of the content of the inorganic matrix 4 in the phosphor layer 3 can be increased, so that the mechanical strength of the wavelength conversion member 1 can be further improved. When the content A of the inorganic phosphor 5 in the phosphor layer 3 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0038] In this embodiment, the thickness T of the phosphor layer 3 is preferably 2 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less.

[0039] When the thickness T of the phosphor layer 3 is equal to or greater than the above lower limit, the mechanical strength of the wavelength conversion member 1 can be further improved. When the thickness T of the phosphor layer 3 is equal to or less than the above upper limit, the luminous intensity of the wavelength conversion member 1 can be further increased. When the thickness T of the phosphor layer 3 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0040] The configuration of each layer of the wavelength conversion member 1 will be described in detail below.

[0041] Plate-shaped members; The shape of the plate-like member 2 is not particularly limited, and can be, for example, a substantially rectangular plate or a substantially circular plate. The thickness of the plate-like member 2 is not particularly limited, and can be, for example, 0.05 mm or more and 2 mm or less, preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, particularly preferably 0.5 mm or more, and preferably 1.5 mm or less, more preferably 1 mm or less, and even more preferably 0.75 mm or less. When the thickness of the plate-like member 2 is equal to or more than the lower limit, the mechanical strength can be further increased. When the thickness of the plate-like member 2 is equal to or less than the upper limit, the scattering and absorption of light in the plate-like member 2 can be further suppressed, and the emission efficiency of the fluorescence can be further increased.

[0042] Any light-transmitting material can be used for the plate-shaped member 2. Examples of materials for the plate-shaped member 2 include transparent materials and materials with a high haze value, regardless of whether they are colorless or colored.

[0043] The haze value of the plate-shaped member 2 is not particularly limited, and may be 1% or more, 5% or more, or 10% or more, and may be 70% or less, 60% or less, or 50% or less.

[0044] The plate-like member 2 is preferably transparent. The total light transmittance of the plate-like member 2 at a wavelength of 450 nm and a thickness of 1 mm is preferably 70% or more, more preferably 75% or more, and further preferably 80% or more. The upper limit of the total light transmittance of the plate-like member 2 at a wavelength of 450 nm and a thickness of 1 mm is not particularly limited, but may be 95% or less, 93% or less, or 90% or less.

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

[0046] The material of the plate-shaped member 2 is not particularly limited, and may be, for example, a translucent ceramic. 2 O 3 , MgO, ZrO 2 , Y 2 O 3 and oxide ceramics such as SiO 2 , sapphire single crystal, etc. Among these, from the viewpoint of further improving the heat resistance of the wavelength conversion member 1, it is preferable that the plate-shaped member 2 is a sapphire substrate or a light-transmitting alumina substrate.

[0047] The material of the plate-shaped member 2 may be glass. Examples of glass that can be used include borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, and tellurite glass. When the plate-shaped member 2 is a glass substrate, the adhesion to the inorganic matrix 4 can be further improved, particularly when the inorganic matrix 4 is a glass matrix.

[0048] Phosphor layer; The phosphor layer 3 includes an inorganic matrix 4 and an inorganic phosphor 5. The inorganic phosphor 5 is dispersed in the inorganic matrix 4.

[0049] The inorganic matrix 4 is not particularly limited as long as it can be used as a dispersion medium for the inorganic phosphor 5, and for example, a glass matrix can be used. As the glass matrix, for example, borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, tellurite glass, etc. can be used.

[0050] Borosilicate glass contains, by mass%, SiO 2 30%~85%, Al 2 O 3 0%~30%, B 2 O 3 0%~50%, Li 2 O+Na 2 O+K 2 Examples of phosphate-based glass include those containing, in mole percent, 0% to 10% O and 0% to 50% MgO+CaO+SrO+BaO.2 O 5 The tin phosphate glass contains, in mole percent, 30% to 90% SnO and P 2 O 5 Examples of bismuthate glass include those containing 1% to 70% by mass. 2 O 3 20%~70%, and B 2 O 3 The tellurite glass contains, in mole percent, TeO 2 50% or more, ZnO 0% to 45%, RO (R is at least one selected from Ca, Sr and Ba) 0% to 50%, and La 2 O 3 +Gd 2 O 3 +Y 2 O 3 Examples include those containing 0% to 50%.

[0051] The softening point of the glass matrix is ​​preferably from 250°C to 1000°C, more preferably from 300°C to 950°C, and further preferably from 500°C to 900°C.

[0052] If the softening point of the glass matrix is ​​too low, the mechanical strength and chemical durability of the wavelength conversion member 1 may decrease. In addition, since the heat resistance of the glass matrix itself is low, there is a risk of it softening and deforming due to the heat generated by the inorganic phosphor 5. On the other hand, if the softening point of the glass matrix is ​​too high, when a firing step is included in the manufacturing process, the inorganic phosphor 5 may deteriorate, and the luminescence intensity of the wavelength conversion member 1 may decrease.

[0053] From the viewpoint of further increasing the chemical stability and mechanical strength of the wavelength conversion member 1, the softening point of the glass matrix is ​​preferably 500° C. or higher, more preferably 600° C. or higher, even more preferably 700° C. or higher, particularly preferably 800° C. or higher, and most preferably 850° C. or higher. Examples of glasses constituting such a glass matrix include borosilicate glasses.

[0054] However, when the softening point of the glass matrix is ​​high, the firing temperature also becomes high, and as a result, the manufacturing cost tends to become high. Furthermore, if the heat resistance of the inorganic phosphor 5 is low, it may be deteriorated by firing. Therefore, when the wavelength conversion member 1 is to be manufactured more inexpensively or when the heat resistance of the inorganic phosphor 5 is low, the softening point of the glass matrix is ​​preferably 550°C or less, more preferably 530°C or less, even more preferably 500°C or less, particularly preferably 480°C or less, and most preferably 460°C or less. Examples of glasses constituting such a glass matrix include tin phosphate glass, bismuthate glass, and tellurite glass.

[0055] The inorganic matrix 4 may be a ceramic matrix. When the inorganic matrix 4 is a ceramic matrix, the heat resistance of the wavelength conversion member 1 can be further improved. Examples of ceramics constituting the ceramic matrix include Al. 2 O 3 , MgO, AlN, etc.

[0056] The inorganic phosphor 5 is not particularly limited as long as it emits fluorescence when excitation light is incident on it. Examples of the inorganic phosphor 5 include oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, oxychloride phosphors, sulfide phosphors, oxysulfide phosphors, halide phosphors, chalcogenide phosphors, aluminate phosphors, halophosphate chloride phosphors, and garnet compound phosphors. One type of these phosphors may be used alone, or multiple types may be used in combination. When blue light is used as the excitation light, for example, a phosphor that emits yellow light as fluorescence may be used. Examples of phosphors that emit yellow light as fluorescence include (Y,Gd) 3 (Al,Ga) 5 O 12 : Ce (YAG phosphor), Lu 3 Al 5 O 12 : Ce, La 3 S 6 N 11 : Ce, Si 6-z Al zO z N 8-z : Eu(0 < z < 4.2)(β-SiAlON:Eu), Ca-α-sialon:Eu, or Li 2 SrSiO 4 :Eu, etc. may be mentioned.

[0057] The density of the inorganic phosphor 5 is not particularly limited, and may be 3.0 g / cm 3 or more, or 3.5 g / cm 3 or more, and may be 6.0 g / cm 3 or less, or 5.5 g / cm 3 or less. When the density of the inorganic phosphor 5 is within the above range, the parameter P represented by the above formula (1) can be adjusted to a more suitable range.

[0058] The surface area per unit mass of the inorganic phosphor 5 is not particularly limited, and is preferably 0.01 m 2 / g or more, more preferably 0.05 m 2 / g or more, still more preferably 0.1 m 2 / g or more, preferably 10 m 2 / g or less, more preferably 5 m 2 / g or less, still more preferably 2 m 2 / g or less. When the surface area per unit mass of the inorganic phosphor 5 is within the above range, the light extraction efficiency in the wavelength conversion member 1 can be further effectively increased.

[0059] The average particle diameter D of the inorganic phosphor 5 50 is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, and preferably 30 μm or less, more preferably 25 μm or less, still more preferably 20 μm or less. The average particle diameter D of the inorganic phosphor 5 50 is when it is above the above lower limit value, the quantum efficiency can be further improved, and the emission intensity by the wavelength conversion member 1 can be further increased. Also, the average particle diameter D of the inorganic phosphor 5 50When the average particle diameter D is equal to or less than the upper limit, the dispersibility of the inorganic phosphor 5 in the inorganic matrix 4 can be further increased, and the emission color of the wavelength conversion member 1 can be made more uniform. 50 is the particle diameter D at which the cumulative frequency is 50% by volume in the volume-based particle size distribution measured by a laser diffraction particle size distribution analyzer. 50 This refers to the following.

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

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

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

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

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

[0065] In the manufacturing method of wavelength conversion member 1, in the step of forming phosphor layer 3, when the surface area per unit volume of inorganic phosphor 5 (inorganic phosphor particles) is S (1 / cm), the content of inorganic phosphor 5 in phosphor layer 3 is A (volume %), and the thickness of phosphor layer 3 is T (μm), S (1 / cm), A (volume %), and T (μm) are adjusted so that parameter P represented by the following formula (1) is 1000 or more and 4500 or less. As a result, the manufacturing method of wavelength conversion member 1 can effectively increase the light extraction efficiency of the obtained wavelength conversion member 1.

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

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

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

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

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

[0071] In the wavelength conversion member 21 of the present embodiment, when the surface area per unit volume of the inorganic phosphor 5 in the phosphor layer 3 is S (1 / cm), the content of the inorganic phosphor 5 in the phosphor layer 3 is A (volume %), and the thickness of the phosphor layer 3 is T (μm), the parameter P expressed by the above formula (1) is 1000 or more and 4500 or less, and therefore the light extraction efficiency of the wavelength conversion member 21 can be effectively increased.

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

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

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

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

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

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

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

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

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

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

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

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

[0084] [Table 1]

[0085] The surface area per unit mass of each inorganic phosphor was measured using a fully automatic specific surface area measuring device (Mountec Co., Ltd., product number "HM model-1201"). The surface area per unit volume of the inorganic phosphor was calculated by multiplying the BET surface area per unit mass of the inorganic phosphor by the density.

[0086] In addition, the average particle diameter D 50 was measured using a laser diffraction particle size distribution analyzer (Shimadzu Corporation, model number "SALD-7500").

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

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

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

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

[0091] In the phosphor layer formed in Example 1, the surface area per unit volume of inorganic phosphor a is S (1 / cm), the content of inorganic phosphor a in the phosphor layer is A (volume %), and the thickness of the phosphor layer is T (μm), and the value of parameter P represented by the following formula (1) was calculated. In formula (1), the content A of inorganic phosphor a is multiplied by the volume ratio of the content of inorganic phosphor a to the entire material in the phosphor layer.

[0092] P=S 0.5 ×A×T…Formula (1)

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

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

[0095] [Table 2]

[0096] Fig. 6 is a graph showing the relationship between the value of parameter P and the fluorescence peak intensity in Examples 1 to 4 and Comparative Examples 1 and 2. As shown in Fig. 6, it can be seen that the fluorescence peak intensity is effectively increased when the value of parameter P is 1000 or more and 4500 or less.

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

[0098] [Table 3]

[0099] Fig. 7 is a graph showing the relationship between the value of parameter P and the fluorescence peak intensity in Examples 5 to 8 and Comparative Example 3. As shown in Fig. 7, it can be seen that the fluorescence peak intensity is effectively increased when the value of parameter P is 1000 or more and 4500 or less. [Explanation of symbols]

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

Claims

1. A plate-like member; A phosphor layer provided on a main surface of the plate-shaped member; Equipped with the phosphor layer includes an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix; A wavelength conversion member, wherein a parameter P represented by the following formula (1) is 1000 or more and 4500 or less, where S (1 / cm) is a surface area per unit volume of the inorganic phosphor, A (volume %) is a content of the inorganic phosphor in the phosphor layer, and T (μm) is a thickness of the phosphor layer. P = S ０．５ ×A×T …Formula (1)

2. 2. The wavelength conversion member according to claim 1, wherein a surface area S per unit volume of the inorganic phosphor is 4000 (1 / cm) or more and 100000 (1 / cm) or less.

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

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

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

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

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

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

9. the plate-like member has a first main surface and a second main surface opposed to each other; The phosphor layer is provided on the first main surface side of the plate-shaped member, The wavelength conversion member according to claim 1 or 2, further comprising a bandpass filter provided between the first main surface of the plate-shaped member and the phosphor layer, or on the second main surface of the plate-shaped member.

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

11. preparing a plate-like member; forming a phosphor layer on a main surface of the plate-like member, the phosphor layer including an inorganic matrix and an inorganic phosphor dispersed in the inorganic matrix; Equipped with a surface area per unit volume of the inorganic phosphor is S (1 / cm), a content of the inorganic phosphor in the phosphor layer is A (volume %), and a thickness of the phosphor layer is T (μm), the method for manufacturing a wavelength conversion member comprising adjusting S (1 / cm), A (volume %), and T (μm) so that a parameter P represented by the following formula (1) is 1000 or more and 4500 or less: P = S ０．５ ×A×T …Formula (1)

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