WO2022210009A1

WO2022210009A1 - Wavelength conversion member and light emission device

Info

Publication number: WO2022210009A1
Application number: PCT/JP2022/012515
Authority: WO
Inventors: 直輝上田
Original assignee: 日本電気硝子株式会社
Priority date: 2021-04-01
Filing date: 2022-03-18
Publication date: 2022-10-06
Also published as: CN117120886A; JP2022158107A; KR20230161940A; TW202239940A

Abstract

Provided is a wavelength conversion member that can efficiently excite phosphors even when ultraviolet light is used as excitation light, and suppress the degradation of peripheral members due to ultraviolet light leakage, as well as the effect of such leakage on the human body.　A wavelength conversion member 1 for converting the wavelength of excitation light emitted from a light source 7 comprises: a first layer 2 composed of a first glass matrix 4 and phosphor particles 5 distributed in the first glass matrix 4; and a second layer 3 provided on the first layer 2 and composed of a second glass matrix 6, wherein the first layer 2 is provided on the light source 7 side, the difference |T_A-T_B| between the transmittance T_A of the first glass matrix 4 and the transmittance T_B of the second glass matrix 6 at an excitation wavelength is greater than the difference |L_A-L_B| between the transmittance L_A of the first glass matrix 4 and the transmittance L_B of the second glass matrix 6 at a fluorescence wavelength, and T_A>T_B.

Description

Wavelength conversion member and light emitting device

The present invention relates to a wavelength conversion member that converts the wavelength of light emitted by a light emitting diode (LED) or a laser diode (LD) into another wavelength, and a light emitting device using the wavelength conversion member.

In recent years, there has been increasing interest in light-emitting devices using LEDs and LDs as next-generation light-emitting devices to replace fluorescent lamps and incandescent lamps, from the viewpoint of low power consumption, small size and light weight, and easy light intensity adjustment. As an example of such a light-emitting device, for example, in Patent Document 1 below, a wavelength conversion member that absorbs part of the light from the LED and converts it into yellow light is arranged on an LED that emits blue light. A light emitting device is disclosed. This light-emitting device emits white light, which is synthesized light of blue light emitted from the LED and yellow light emitted from the wavelength conversion member.

As light-emitting devices using LEDs and LDs, not only general lighting applications but also light-emitting devices for sensing combined with wavelength conversion members and sensors have been proposed. For example, Patent Document 2 below discloses a light source for a methane gas sensor that includes a light emitting element that emits ultraviolet light and/or visible light, and a phosphor layer provided on the light emitting element.

Japanese Patent Application Laid-Open No. 2000-208815 JP 2013-170205 A

If the excitation light leaks out together with the fluorescence, it may adversely affect the function as a sensor. Furthermore, when the wavelength of ultraviolet light is short, it tends to adversely affect the human body. Therefore, in the light-emitting device described in Patent Document 2, a filter is formed on the surface of the phosphor layer that does not transmit the excitation light but only the fluorescence. However, forming such a filter on the surface of the phosphor layer complicates the manufacturing process, leading to an increase in cost.

In view of the above, the present invention is capable of efficiently exciting phosphors even when ultraviolet light is used as excitation light, and suppresses deterioration of surrounding members and effects on the human body due to leakage of ultraviolet light. It is an object of the present invention to provide a wavelength conversion member and a light-emitting device using the wavelength conversion member.

A wavelength conversion member according to the present invention is a wavelength conversion member for converting the wavelength of excitation light emitted from a light source, and comprises a first glass matrix and fluorescent light dispersed in the first glass matrix. a first layer composed of body particles; and a second layer provided on the first layer and composed of a second glass matrix; is provided on the light source side, and the difference |T _A −T _B | between the transmittance T _A of the first glass matrix and the transmittance T _B of the second glass matrix at the excitation wavelength is greater than the difference |L _A −L _B | between the transmittance L _A of the first glass matrix and the transmittance L _B of the second glass matrix at the fluorescence wavelength, and T _A >T _B ; Characterized by

In the present invention, the difference |T _A −T _B |−|L _A −L _B | between the transmittance difference at the excitation wavelength and the transmittance difference at the fluorescence wavelength is preferably 20% or more.

In the present invention, the transmittance T _A of the first glass matrix at the excitation wavelength is 20% or more, and the transmittance T _B of the second glass matrix at the excitation wavelength is 65% or less. preferable.

In the present invention, the transmittance LA of the first glass matrix at the fluorescence wavelength is 50% or more, and the transmittance _LB of the second glass matrix at the fluorescence _wavelength is 50% or more. preferable.

In the present invention, it is preferable that the second layer does not substantially contain phosphor particles.

In the present invention, the thickness of the second layer is preferably greater than the thickness of the first layer.

In the present invention, the thickness ratio of the second layer to the first layer (second layer/first layer) is preferably 1 or more and 30 or less.

In the present invention, the excitation light is preferably UV light.

In the present invention, the fluorescence is preferably visible light.

A light-emitting device according to the present invention is characterized by comprising a light source that emits excitation light and a wavelength conversion member configured according to the present invention.

According to the present invention, even when UV light is used as the excitation light, it is possible to efficiently excite the phosphor, and without using an external filter, deterioration of surrounding members and damage to the human body due to leakage of UV light can be achieved. It is possible to provide a wavelength conversion member and a light-emitting device using the wavelength conversion member that can suppress the influence.

FIG. 1 is a schematic front cross-sectional view showing a wavelength conversion member according to one embodiment of the present invention. FIG. 2 is a diagram showing an example of transmittance spectra of the first glass matrix and the second glass matrix. FIG. 3 is a schematic front sectional view showing a light emitting device according to one embodiment of the invention. FIG. 4 is a schematic front cross-sectional view showing a modification of the light emitting device according to one embodiment of the present invention. FIG. 5 is a diagram showing an example of an energy distribution spectrum of light emitted from the emission surface side of the wavelength conversion member when UVLED is irradiated.

A preferred embodiment will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Also, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

[Wavelength conversion member]
FIG. 1 is a schematic front cross-sectional view showing a wavelength conversion member according to one embodiment of the present invention. As shown in FIG. 1, the wavelength conversion member 1 of this embodiment has a rectangular plate shape. However, the wavelength conversion member 1 may have a substantially disk-like shape, and the shape is not particularly limited.

The wavelength conversion member 1 has a first layer 2 and a second layer 3 . The first layer 2 has a first major surface 2a and a second major surface 2b. A second layer 3 is provided on the first main surface 2 a of the first layer 2 . The second main surface 2b of the first layer 2 is the surface on which the light source 7 is provided. Therefore, the second layer 3 is provided on the side opposite to the light source 7 side.

The first layer 2 is phosphor glass composed of a first glass matrix 4 and phosphor particles 5 . In this embodiment the phosphor particles 5 are dispersed in the first glass matrix 4 . Also, the second layer 3 is composed of a second glass matrix 6 .

In this embodiment, excitation light A from the light source 7 is emitted to the wavelength conversion member 1 as shown in FIG. The excitation light A enters the first layer 2 from the second main surface 2b side. When the first layer 2 on which the phosphor is arranged is irradiated with the excitation light A, fluorescence B is emitted. Fluorescence B passes through the second layer 3 and is emitted from the wavelength conversion member 1 .

FIG. 2 is a diagram showing an example of transmittance spectra of the first glass matrix 4 and the second glass matrix 6 that constitute such a wavelength conversion member 1. FIG. Note that FIG. 2 shows individual transmittance spectra of the first glass matrix 4 and the second glass matrix 6, respectively. The transmittance spectra of the first glass matrix 4 and the second glass matrix 6 are each measured on a glass plate with a thickness of 1 mm. This glass plate is produced by vacuum firing a green compact of glass powder (average particle size: 2.5 μm), which is the raw material of the first glass matrix 4 or the second glass matrix 6, at the softening point of the glass powder +50° C. After obtaining the sintered body, the obtained sintered body can be produced by cutting, lapping, or polishing so as to have a thickness of 1 mm. The transmittance indicated in this patent represents the total light transmittance of a polished sintered body having a thickness of 1 mm, and can be measured by a method conforming to JIS K7105. Also, the transmittance spectra of the first glass matrix 4 and the second glass matrix 6 can be measured with a spectrophotometer.

As shown in FIG. 2, in this embodiment, the absolute value of the difference between the transmittance T _A of the first glass matrix 4 and the transmittance T _B of the second glass matrix 6 at the excitation wavelength |T _A −T _B | is greater than the absolute value |L _A −L _B | of the difference between the transmittance L _A of the first glass matrix 4 and the transmittance L _B of the second glass matrix 6 at the fluorescence wavelength. More specifically, the transmittance T _A of the first glass matrix 4 is greater than the transmittance T _B of the second glass matrix 6 at the excitation wavelength. On the other hand, at the fluorescence wavelength, both the transmittance L _A of the first glass matrix 4 and the transmittance L _B of the second glass matrix 6 are large, and the difference between them is small. In the present invention, the excitation wavelength means the wavelength at which the emission intensity of the excitation light source is maximized, and the fluorescence wavelength means the wavelength at which the fluorescence intensity is maximized. In this embodiment, the transmittance of the excitation wavelength refers to the transmittance of UV light, specifically, wavelengths of 200 nm to 380 nm. Further, the transmittance of the fluorescence wavelength means the transmittance of visible light, specifically, wavelengths of 380 nm to 800 nm.

When UV light as the excitation light A is incident on the wavelength conversion member 1 using the first glass matrix 4 and the second glass matrix 6 having such optical properties, the first layer 2 is formed. Since the first glass matrix 4 has a high transmittance at the excitation wavelength, absorption of the excitation light A by the glass can be reduced, and the wavelength can be efficiently converted into fluorescent light in the first layer 2 . On the other hand, in the second layer 3, since the second glass matrix 6 constituting the second layer 3 has a low transmittance at the excitation wavelength, the second layer 3 shields the UV light, which is the excitation light A. can do. Therefore, it is possible to suppress the deterioration of peripheral members and the influence on the human body due to the leakage of UV light. Moreover, since the transmittance of the first glass matrix 4 and the second glass matrix 6 constituting the first layer 2 and the second layer 3 is high at the fluorescence wavelength, the fluorescence can be efficiently emitted. Therefore, according to the wavelength conversion member 1 of the present embodiment, even when UV light is used as the excitation light A, the phosphor can be efficiently excited, and furthermore, leakage of the UV light can cause deterioration of peripheral members and human body. can reduce the impact on

In the present invention, the difference |T _A −T _B |−|L _A −L _B | between the transmittance difference at the excitation wavelength and the transmittance difference at the fluorescence wavelength is preferably 20% or more, more preferably It is 40% or more, more preferably 60% or more, and particularly preferably 75% or more. When the difference |T _A −T _B |−|L _A −L _B | is equal to or greater than the lower limit, the phosphor can be excited more efficiently, and furthermore, the leakage of UV light can cause deterioration of surrounding members and damage to the human body. can be further suppressed. The upper limit of the difference |T _A −T _B |−|L _A −L _B | is not particularly limited, but can be, for example, 95%.

In the present invention, the thickness of the second layer 3 is preferably greater than the thickness of the first layer 2. In this case, the emission efficiency of fluorescence can be further increased while blocking UV light more reliably.

In particular, the thickness ratio of the second layer 3 to the first layer 2 (second layer 3/first layer 2) is preferably 1 or more, more preferably 1.5 or more, and still more preferably 2 or more. , preferably 30 or less, more preferably 10 or less, still more preferably 7 or less. When the thickness ratio (second layer 3/first layer 2) is equal to or greater than the lower limit, UV light can be shielded more reliably and fluorescence emission efficiency can be further increased. On the other hand, when the thickness ratio (second layer 3/first layer 2) is equal to or less than the upper limit, the emission intensity of the wavelength conversion member can be further increased.

The thickness of the entire wavelength conversion member 1 is preferably 0.1 mm or more, more preferably 0.125 mm or more, still more preferably 0.15 mm or more, particularly preferably 0.175 mm or more, and most preferably 0.2 mm or more. be. The thickness of the entire wavelength conversion member 1 is preferably 1.5 mm or less, more preferably 1 mm or less, still more preferably 0.75 mm or less, particularly preferably 0.5 mm or less, most preferably 0.3 mm or less. When the thickness of the entire wavelength conversion member 1 is equal to or greater than the above lower limit, the emission intensity and mechanical strength of the wavelength conversion member 1 can be further enhanced. Moreover, when the thickness of the wavelength conversion member 1 is equal to or less than the upper limit value, the scattering and absorption of light in the wavelength conversion member 1 can be further suppressed, and the fluorescence emission efficiency can be further increased.

In addition, as will be described later, the first glass matrix 4 and the second glass matrix 6 are basically produced by stacking and co-firing green sheets serving as raw materials for each layer. The difference in softening point between the glass powder used for the matrix 4 and the glass powder used for the second glass matrix 6 is preferably small. The difference in softening point between the glass powder used for the first glass matrix 4 and the glass powder used for the second glass matrix 6 is preferably 200°C or less, more preferably 100°C or less, and still more preferably 50°C. Below, the temperature is particularly preferably 10° C. or less, and it is most preferable that both softening points are the same.

(first layer)
The first layer 2 is composed of a first glass matrix 4 and phosphor particles 5 dispersed in the first glass matrix 4 .

a first glass matrix;
The first glass matrix 4 is made of glass that can be used as a dispersion medium for phosphor particles 5 such as an inorganic phosphor. The first glass matrix 4 is made of glass that transmits UV light and fluorescent light (UV light transmitting glass).

The transmittance _TA of the first glass matrix 4 at the excitation wavelength is preferably 20% or more, more preferably 40% or more, even more preferably 60% or more, and particularly preferably 80% or more. When the transmittance T _A of the first glass matrix 4 at the excitation wavelength is equal to or higher than the above lower limit, the absorption of the excitation light by the glass can be further reduced, and fluorescence can be emitted in the first layer 2 more efficiently. can be emitted. Although the upper limit of the transmittance _TA of the first glass matrix 4 at the excitation wavelength is not particularly limited, it can be set to 95%, for example.

The transmittance _LA of the first glass matrix 4 at the fluorescence wavelength is preferably 50% or more, more preferably 75% or more, and even more preferably 80% or more. When the transmittance _LA of the first glass matrix 4 at the fluorescence wavelength is equal to or higher than the above lower limit value, the fluorescence can be more efficiently emitted from the first layer 2 . The upper limit of the transmittance _LA of the first glass matrix 4 at the fluorescence wavelength is not particularly limited, and can be set to 95%, for example.

The glass constituting the first glass matrix 4 is not particularly limited as long as it has the optical properties described above. system glass and tellurite system glass can be used.

Specific examples of the glass constituting the first glass matrix 4 include, in terms of mol %, SiO ₂ 40% to 60%, B ₂ O ₃ 0.1% to 35%, and Al ₂ O ₃ 0.1%. ~10%, Li2O 0%~10%, _Na2O ₀ %~10%, K2O 0%~10%, Li2O ₊ _Na2O ₊ _K2O 0.1%~10%, MgO 0%~ 45%, CaO 0%-45%, SrO 0%-45%, BaO 0%-45%, MgO+CaO+SrO+BaO 0.1%-45%, ZnO 0%-15%.

The glass constituting the first glass matrix 4 is composed of, in mass %, SiO ₂ 55% to 75%, Al ₂ O ₃ 1% to 10%, B ₂ O ₃ 10% to 30%, CaO 0% to 5%. , BaO 0% to 5%, and Li ₂ O+Na ₂ O+K ₂ O 1% to 15%.

The glass constituting the first glass matrix 4 contains, in mass %, SiO ₂ +B ₂ O ₃ 60% to 90%, Li ₂ O+Na ₂ O+K ₂ O 0% to 20%, and MgO+CaO+SrO+BaO 0% to 20%. It may be a glass containing.

If the glass constituting the first glass matrix 4 contains Fe ₂ O ₃ or TiO ₂ , the transmittance of UV light tends to decrease. is preferred. Here, "substantially free" means a raw material that is not intentionally contained, and objectively means less than 1000 ppm.

In this specification, "x + y + ..." means the total content of each component.

The softening point of the first glass matrix 4 is preferably 250°C to 1000°C, more preferably 300°C to 950°C, even more preferably 500°C to 900°C. If the softening point of the first glass matrix 4 is too low, the mechanical strength and chemical durability of the wavelength conversion member 1 may deteriorate. In addition, since the heat resistance of the first glass matrix 4 itself is low, there is a risk of softening deformation due to heat generated from the phosphor particles 5 . On the other hand, if the softening point of the first glass matrix 4 is too high, the phosphor particles 5 may deteriorate and the emission intensity of the wavelength conversion member 1 may decrease if a baking process is included in the manufacturing process. From the viewpoint of further enhancing the chemical stability and mechanical strength of the wavelength conversion member 1, the softening point of the first glass matrix 4 is preferably 500° C. or higher, more preferably 600° C. or higher, and still more preferably 600° C. or higher. 650° C. or higher. However, when the softening point of the first glass matrix 4 increases, the firing temperature also increases, which tends to increase the manufacturing cost. Moreover, if the heat resistance of the phosphor particles 5 is low, there is a risk of deterioration due to firing. Therefore, when the wavelength conversion member 1 is manufactured at a lower cost, or when the heat resistance of the phosphor particles 5 is lower, the softening point of the first glass matrix 4 is preferably 550° C. or less, more preferably 530° C. C. or lower, more preferably 500.degree. C. or lower, particularly preferably 480.degree. C. or lower, and most preferably 460.degree.

phosphor particles;
The phosphor particles 5 are not particularly limited as long as they emit fluorescence upon incidence of excitation light. Examples of phosphor particles 5 include oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, acid chloride phosphors, sulfide phosphors, oxysulfide phosphors, and halide phosphors. phosphors, chalcogenide phosphors, aluminate phosphors, halophosphate phosphors, garnet-based compound phosphors, and the like. One type of these phosphors may be used alone, or a plurality of types may be used in combination. Phosphors that absorb UV light and emit visible light include, for example, Lu ₃ Al ₅ O ₁₂ (fluorescence wavelength: 550 nm), Si _6-z Al _z O _z N _8-z : Eu (0<z<4 .2) (=β-SiAlON:Eu) (fluorescence wavelength: 545 nm), La ₃ Si ₆ N ₁₁ :Ce (fluorescence wavelength: 535 nm), and the like.

The average particle size of the phosphor particles 5 is preferably 1 μm or more, more preferably 5 μm or more. If the average particle size of the phosphor particles 5 is too small, the quantum efficiency tends to be poor and the emission intensity tends to decrease. On the other hand, if the average particle diameter of the phosphor particles 5 is too large, the dispersion state in the first glass matrix 4 deteriorates, and the emission color tends to be non-uniform. Therefore, the average particle size of the phosphor particles 5 is preferably 50 μm or less, more preferably 25 μm or less.

In this specification, the average particle size means the average particle size _D50 measured by a laser diffraction particle size distribution analyzer.

The content of the phosphor particles 5 in the first layer 2 is preferably 1% by volume or more, more preferably 3% by volume or more, and even more preferably 5% by volume or more. The content of the phosphor particles 5 in the first layer 2 is preferably 70% by volume or less, more preferably 65% by volume or less, and even more preferably 50% by volume or less. If the content of the phosphor particles 5 is too small, it is necessary to increase the thickness of the first layer 2 in order to obtain the desired fluorescence intensity, and as a result, the internal scattering of the wavelength conversion member 1 and the absorption by the matrix increase. As a result, the light extraction efficiency may decrease. On the other hand, if the content of the phosphor particles 5 is too large, the ratio of the glass is relatively decreased, and the strength of the glass to support the phosphor is weakened, which may reduce the mechanical strength of the wavelength conversion member 1. be.

In this embodiment, the second glass matrix 6 is made of a powder sintered body of only glass powder, but is not limited to this. For example, the second glass matrix 6 may contain other inorganic powder such as filler powder for the purpose of adjusting the coefficient of thermal expansion and obtaining a light scattering effect. By doing so, the thermal expansion coefficients of the first layer 2 and the second layer 3 can be easily matched, and the occurrence of warpage, cracks, etc. of the wavelength conversion member 1 due to the difference in thermal expansion coefficients can be reduced. can be further suppressed. Moreover, the light scattering effect of the filler powder can further improve the emission intensity of the wavelength conversion member 1 . Furthermore, the heat dissipation efficiency of the wavelength conversion member 1 can be further improved by containing a filler powder with a high thermal conductivity. Filler powders include MgO, Al ₂ O ₃ , BN, AlN, and the like. Among them, MgO, Al ₂ O ₃ and BN are preferable because of their excellent transmittance in the visible region.

a first layer;
The thickness of the first layer 2 is not particularly limited, but is preferably 0.01 mm or more, more preferably 0.03 mm or more, preferably 0.5 mm or less, and more preferably 0.3 mm or less. be. When the thickness of the 1st layer 2 is more than the said lower limit, the light emission intensity and mechanical strength of the wavelength conversion member 1 can be heightened further. Moreover, when the thickness of the first layer 2 is equal to or less than the above upper limit, the scattering and absorption of light in the first layer 2 can be further suppressed, and the emission efficiency of fluorescence can be further increased.

(second layer)
The second layer 3 is composed of a second glass matrix 6 . The second glass matrix 6 is made of glass (such as UV light shielding glass) that shields excitation light (eg, UV light) and allows fluorescence to pass through.

The transmittance T _B of the second glass matrix 6 at the excitation wavelength is preferably 65% or less, more preferably 40% or less, even more preferably 20% or less, and particularly preferably 10% or less. . When the transmittance T _B of the excitation wavelength of the second glass matrix 6 is equal to or less than the above upper limit, the excitation light can be shielded more reliably in the second layer 3. For example, when the excitation light is UV light, In addition, deterioration of peripheral members and effects on the human body due to the leakage can be more reliably suppressed. Although the lower limit of the transmittance T _B of the second glass matrix 6 at the excitation wavelength is not particularly limited, it can be set to 0%, for example.

The transmittance L _B of the second glass matrix 6 at the fluorescence wavelength is preferably 50% or more, more preferably 75% or more, still more preferably 80% or more. When the transmittance _LB of the second glass matrix 6 at the fluorescence wavelength is equal to or higher than the above lower limit, fluorescence can be emitted more efficiently from the wavelength conversion member 1 . The upper limit of the transmittance L _B of the second glass matrix 6 at the fluorescence wavelength is not particularly limited, and can be set to 95%, for example.

The glass constituting the second glass matrix 6 is not particularly limited as long as it has the optical properties described above. system glass and tellurite system glass can be used.

Specific examples of the glass constituting the second glass matrix 6 include, in terms of mol %, SiO ₂ 40% to 60%, B ₂ O ₃ 0.1% to 35%, and Al ₂ O ₃ 0.1%. ~10%, Li2O 0%~10%, _Na2O ₀ %~10%, K2O 0%~10%, Li2O ₊ _Na2O ₊ _K2O 0.1%~10%, MgO 0%~ 45%, CaO 0%-45%, SrO 0%-45%, BaO 0%-45%, MgO+CaO+SrO+BaO 0.1%-45%, ZnO ₀ %-15%, CeO2 0.001%-10% Containing glasses can be used.

The glass constituting the second glass matrix 6 is SiO ₂ 30% to 85%, Al ₂ O ₃ 0% to 30%, B ₂ O ₃ 0% to 50%, and Li ₂ O + Na ₂ O + K ₂ in mass %. The glass may contain 0% to 10% O and 0% to 50% MgO+CaO+SrO+BaO.

The softening point of the second glass matrix 6 is preferably 250°C to 1000°C, more preferably 300°C to 950°C, even more preferably 500°C to 900°C. If the softening point of the second glass matrix 6 is too low, the mechanical strength and chemical durability of the wavelength conversion member 1 may deteriorate. On the other hand, if the softening point of the second glass matrix 6 is too high, the phosphor particles 5 may deteriorate and the emission intensity of the wavelength conversion member 1 may decrease if a baking process is included in the manufacturing process.

a second layer;
The thickness of the second layer 3 is not particularly limited, but is preferably 0.05 mm or more, more preferably 0.1 mm or more, preferably 1 mm or less, and more preferably 0.5 mm or less. When the thickness of the second layer 3 is at least the above lower limit, the excitation light can be shielded more reliably in the second layer 3. For example, when the excitation light is UV light, the leakage of the surrounding members deterioration and the effects on the human body can be suppressed more reliably. Moreover, when the thickness of the second layer 3 is equal to or less than the upper limit value, the scattering and absorption of light in the second layer 3 can be further suppressed, and the fluorescence emission efficiency can be further increased.

It is desirable that the second layer 3 does not substantially contain phosphor particles. However, the second layer 3 may contain phosphor particles.

(Manufacturing method of wavelength conversion member)
An example of the method for manufacturing the wavelength conversion member will be described below.

First, a green sheet for forming the first layer is prepared. Specifically, a slurry containing glass particles to be the first glass matrix 4 and phosphor particles 5 is prepared. The slurry usually contains a binder resin and a solvent. Subsequently, the prepared slurry is applied onto the support base material, and a doctor blade placed at a predetermined distance from the base material is moved relative to the slurry, thereby forming the first layer-forming green sheet. Form. As the supporting substrate, for example, a resin film such as polyethylene terephthalate can be used.

Next, a green sheet for forming the second layer is prepared. Specifically, a slurry containing glass particles to be the second glass matrix 6 is prepared, and a second layer-forming green sheet is obtained in the same manner as described above.

The materials of the glass particles that form the first glass matrix 4 and the second glass matrix 6 can be the same as the materials of the first glass matrix 4 and the second glass matrix 6 described above. Also, the average particle size of the glass particles is preferably 0.1 μm or more, more preferably 1 μm or more, and still more preferably 2 μm or more. If the average particle size of the glass particles is too small, the production cost tends to increase and the handleability tends to deteriorate. On the other hand, if the average particle size of the glass particles is too large, bubbles tend to remain in the glass matrix after firing in the obtained wavelength conversion member 1, and the light extraction efficiency of the wavelength conversion member 1 may decrease. Therefore, the average particle size of the glass particles is preferably 100 µm or less, more preferably 50 µm or less, still more preferably 20 µm or less, and particularly preferably 10 µm or less. Moreover, it is desirable that the average particle size of the phosphor particles is within the range described for the first layer 2 above.

Next, the first layer-forming green sheet and the second layer-forming green sheet are laminated by thermocompression bonding or the like to obtain a laminate. Subsequently, the laminated body is fired at about the softening point of the glass particles to the softening point of the glass particles +100° C., thereby obtaining a wavelength conversion member made of a sintered body in which the first layer 2 and the second layer 3 are laminated. 1 can be obtained. The firing is preferably performed in a reduced pressure atmosphere, and more preferably in a vacuum atmosphere. In this case, it is possible to obtain the wavelength conversion member 1 which is even more excellent in denseness. Moreover, it is preferable to bake the laminate while sandwiching it between a pair of restraining members. In this case, the flatness of the wavelength conversion member 1 (in particular, the flatness of the interface between the first layer 2 and the second layer 3) is improved, and it becomes easier to process the wavelength conversion member 1 to a desired thickness in the subsequent polishing process. Before firing, it is preferable to perform a binder removal treatment at a temperature lower than the softening point of the glass particles. In this case, in the obtained wavelength conversion member 1, it is possible to reduce organic component residues that cause light absorption and scattering, and to further improve the emission intensity.

Further, it is preferable to grind the first layer 2 in the obtained sintered body to a desired thickness. Specifically, it is preferable to adjust the chromaticity of the wavelength conversion member 1 by polishing the first layer 2 of the sintered body to a predetermined thickness. The second layer 3 in the obtained sintered body may be ground to a desired thickness.

The method for manufacturing the wavelength conversion member 1 is not limited to the method described above. For example, after separately firing the first layer-forming green sheet and the second layer-forming green sheet, the obtained fired bodies are joined by thermocompression or an adhesive, whereby the wavelength conversion member 1 may be obtained.

[Light emitting device]
FIG. 3 is a schematic front sectional view showing a light emitting device according to one embodiment of the invention. As shown in FIG. 3 , the light emitting device 11 includes the wavelength conversion member 1 according to the embodiment described above and a light source 7 that emits excitation light A to the wavelength conversion member 1 . In the light emitting device 11 , the light source 7 is arranged so that the excitation light A directly enters the wavelength conversion member 1 from the first layer 2 side.

Also in the wavelength conversion member 1 of the light emitting device 11, by providing the first layer 2 and the second layer 3, the phosphor can be efficiently excited, and furthermore, deterioration of peripheral members due to leakage of UV light and damage to the human body can be prevented. The impact can be suppressed.

Note that the arrangement of the light sources 7 is not limited to the above. For example, in the modified example shown in FIG. 4, a light guide plate 12 is arranged between the light source 7 and the wavelength conversion member 1 . The light source 7 is arranged so that the excitation light A is directly incident on the light guide plate 12 . The excitation light A emitted from the light source 7 passes through the light guide plate 12 and enters the wavelength conversion member 1 . Specifically, the excitation light A enters from the end surface 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 suppresses absorption of the excitation light A as much as possible.

The light-emitting device 11 can be suitably used, for example, as a light-emitting device for sensing and high color rendering lighting.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is by no means limited to the following examples, and can be modified as appropriate without changing the gist of the invention.

(Example 1)
As the glass particles to be the first glass matrix, SiO ₂ 45%, Al ₂ O ₃ 4%, B ₂ O ₃ 18%, Li ₂ O 1.5%, Na ₂ O 1.5%, Glass particles A having a composition of 1.5% K ₂ O, 25% BaO, and 3.5% ZnO (softening point: 690° C., coefficient of thermal expansion: 86.1×10 ⁻⁷ /° C., average particle diameter: 2 .5 μm) was prepared.

Next, glass particles A, phosphor particles (Lu ₃ Al ₅ O ₁₂ , average particle size: 15 μm), a binder resin (Oricox manufactured by Kyoeisha Chemical Co., Ltd.), a plasticizer (dioctyl adipate), A slurry-like mixture was obtained by kneading a dispersant (Floren G-700, manufactured by Kyoeisha Chemical Co., Ltd.) and an organic solvent (methyl ethyl ketone). The resulting slurry mixture was formed into a sheet by a doctor blade method and dried at room temperature to obtain a first layer-forming green sheet. The amount of phosphor particles added was adjusted to 30% by volume in the first layer.

Next, as the glass particles to be the second glass matrix, SiO ₂ 45%, Al ₂ O ₃ 4%, B ₂ O ₃ 18%, Li ₂ O 1.5%, Na ₂ O 1.5% by mol %. Glass particles X having a composition of 5%, K ₂ O 1.5%, BaO 25%, ZnO 3%, and CeO ₂ 0.5% (softening point: 690° C., coefficient of thermal expansion: 86.1×10 ⁻⁷ /° C., average particle size: 2.5 μm).

Next, glass particles X, 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 kneaded to obtain a slurry-like mixture. The resulting slurry mixture was formed into a sheet by a doctor blade method and dried at room temperature to obtain a green sheet for forming a second layer.

Next, after cutting the first layer-forming green sheet and the second layer-forming green sheet into a predetermined size, they were thermocompression bonded. After degreasing the obtained laminate in an electric furnace, it is heated to 740° C. (the softening point of the glass particles that form the first glass matrix and the glass particles that form the second glass matrix) in a vacuum gas replacement furnace +50°C) and vacuum firing was carried out. A wavelength conversion member in which a first layer and a second layer are laminated was obtained by polishing the obtained sintered body so that each side thereof had a desired layer thickness. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

(Example 2)
As the glass particles to be the first glass matrix, SiO ₂ 68%, Al ₂ O ₃ 4%, B ₂ O ₃ 19%, Na ₂ O 7%, K ₂ O 1%, F ₂ 1% in mass % Glass particles B (softening point: 700° C., thermal expansion coefficient: 41.9×10 ⁻⁷ /° C., average particle size: 2.5 μm) were prepared.

Further, the glass particles to be the second glass matrix have a composition of 50% SiO ₂ , 6% Al ₂ O ₃ , 5% B ₂ O ₃ , 12% CaO, 25% BaO, and 2% ZnO in mass %. glass particles Y (softening point: 850° C., coefficient of thermal expansion: 68.0×10 ⁻⁷ /° C., average particle size: 2.5 μm) were prepared.

In addition, vacuum firing was performed at 900°C (the softening point of the higher one of the glass particles forming the first glass matrix and the glass particles forming the second glass matrix + 50°C).

Other points were the same as in Example 1 to obtain a wavelength conversion member. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

(Example 3)
As the glass particles to be the first glass matrix, in mass %, SiO ₂ 71%, Al ₂ O ₃ 6%, B ₂ O ₃ 13%, Na ₂ O 7%, K ₂ O 1%, CaO 1%, Glass particles C (softening point: 737° C., coefficient of thermal expansion: 66.0×10 ⁻⁷ /° C., average particle size: 2.5 μm) having a composition of 1% BaO were prepared.

In addition, the same glass particles Y as in Example 2 were prepared as the glass particles forming the second glass matrix.

The transmittance at a wavelength of 250 nm (UV-C transmittance), the transmittance at a wavelength of 280 nm (transmittance at the excitation wavelength), and The results of measuring the transmittance at a wavelength of 300 nm (UV-B transmittance), the transmittance at a wavelength of 350 nm (UV-A transmittance), and the transmittance at a wavelength of 550 nm (VIS transmittance = transmittance at fluorescence wavelength) are shown below. shown in Table 1. The transmittances of the first glass matrix and the second glass matrix were each measured on a glass plate having a thickness of 1 mm. This glass plate was produced by the method described above. Further, the transmittance of the first glass matrix and the second glass matrix was measured with a spectrophotometer (manufactured by JASCO Corporation, product number V-670).

(Comparative example 1)
The same glass particles X as the second glass matrix of Example 1 were prepared as the glass particles forming the first glass matrix.

Next, glass particles X, phosphor particles (Lu ₃ Al ₅ O ₁₂ , average particle size: 15 μm), a binder resin (Oricox, manufactured by Kyoeisha Chemical Co., Ltd.), a plasticizer (dioctyl adipate), A slurry-like mixture was obtained by kneading a dispersant (Floren G-700, manufactured by Kyoeisha Chemical Co., Ltd.) and an organic solvent (methyl ethyl ketone). The resulting slurry mixture was formed into a sheet by a doctor blade method and dried at room temperature to obtain a green sheet. The amount of phosphor particles added was adjusted to 6% by volume in the resulting wavelength conversion member.

Next, after degreasing the obtained green sheet in an electric furnace, it was vacuum fired at 740°C in a vacuum gas replacement furnace. A wavelength conversion member consisting of only the first layer was obtained by subjecting the obtained sintered body to a polishing process so as to obtain a desired layer thickness. In addition, the thickness of the wavelength conversion member was 200 μm.

(Comparative example 2)
The same glass particles A as the first glass matrix of Example 1 were prepared as the glass particles to be the first glass matrix. Otherwise, in the same manner as in Comparative Example 1, a wavelength conversion member consisting of only the first layer was obtained. In addition, the thickness of the wavelength conversion member was 200 μm.

(Comparative Example 3)
The same glass particles A as the first glass matrix of Example 1 were prepared as the glass particles to be the first glass matrix.

In addition, the same glass particles B as the first glass matrix of Example 2 were prepared as the glass particles to form the second glass matrix.

In addition, vacuum firing was performed at 750°C (the softening point of the higher one of the glass particles forming the first glass matrix and the glass particles forming the second glass matrix + 50°C).

(Comparative Example 4)
The same glass particles X as the second glass matrix of Example 1 were prepared as the glass particles forming the first glass matrix.

Also, the same glass particles Y as the second glass matrix of Example 2 were prepared as the glass particles forming the second glass matrix.

(evaluation)
First, the energy distribution spectrum of a UVLED (λp=280 nm) as an excitation light source was measured using an emission spectrum measurement device (manufactured by Ocean Photonics). The peak intensity at this time was defined as I1.

Next, the wavelength conversion members produced in Examples 1 to 3 and Comparative Examples 1 to 4 were irradiated with a UVLED (λp=280 nm), and the energy distribution spectrum of the light emitted from the emission surface side of the wavelength conversion member was obtained. was measured using the same emission spectrometer (manufactured by Ocean Photonics). As an example is shown in FIG. 5, from the obtained energy distribution spectrum, the peak intensity of the transmitted light of the excitation light source was defined as I2, and the fluorescence peak intensity was measured as I3. The measured ratios of I2 to I1 (I2/I1) and I3 to I1 (I3/I1) are shown in Table 2 below.

From Table 2, it can be seen that the wavelength conversion members of Examples 1 to 3 have a small ratio (I2/I1) and can sufficiently shield UV light. Further, the wavelength conversion members of Examples 1 to 3 have a large ratio (I3/I1), and it can be seen that the phosphor can be efficiently excited.

On the other hand, the wavelength conversion members of Comparative Examples 1 and 4 had a small ratio (I3/I1) and could not efficiently excite the phosphor. Moreover, the wavelength conversion members of Comparative Examples 2 and 3 had a large ratio (I2/I1) and could not sufficiently block UV light.

From the above, the transmittance difference |T _A −T _B | between the first glass matrix and the second glass matrix at the excitation wavelength is the transmittance difference |L In the wavelength conversion members of Examples 1 to 3, _where _A _−L _B | Moreover, it was confirmed that the deterioration of surrounding members and the influence on the human body due to the leakage of UV light can be suppressed without using an external filter.

DESCRIPTION OF SYMBOLS 1... Wavelength conversion member 2... First layer 2a... First main surface 2b... Second main surface 3... Second layer 4... First glass matrix 5... Phosphor particles 6... Second glass matrix 7 Light source 11 Light emitting device 12 Light guide plate

Claims

A wavelength conversion member for converting the wavelength of excitation light emitted from a light source,
a first layer composed of a first glass matrix and phosphor particles dispersed in the first glass matrix;
a second layer provided on the first layer and composed of a second glass matrix;
with
The first layer is provided on the light source side,
The difference |T A −T B | between the transmittance T A of the first glass matrix and the transmittance T B of the second glass matrix at the excitation wavelength is the transmittance L of the first glass matrix at the fluorescence wavelength. A and the second glass matrix transmittance L B difference is larger than |L A −L B |, and T A >T B.
The wavelength conversion according to claim 1, wherein a difference |T A −T B |−|L A −L B | between the transmittance difference at the excitation wavelength and the transmittance difference at the fluorescence wavelength is 20% or more. Element.
3. The method according to claim 1 or 2, wherein the first glass matrix has a transmittance TA at an excitation wavelength of 20% or more, and the second glass matrix has a transmittance TB at an excitation wavelength of 65% or less. A wavelength conversion member as described.
4. The method according to any one of claims 1 to 3, wherein the transmittance L A of the first glass matrix at the fluorescence wavelength is 50% or more, and the transmittance L B of the second glass matrix at the fluorescence wavelength is 50% or more. The wavelength conversion member according to any one of items 1 and 2.
The wavelength conversion member according to any one of claims 1 to 4, wherein the second layer does not substantially contain phosphor particles.
The wavelength conversion member according to any one of claims 1 to 5, wherein the thickness of the second layer is greater than the thickness of the first layer.
The wavelength according to any one of claims 1 to 6, wherein the thickness ratio of the second layer to the first layer (second layer/first layer) is 1 or more and 30 or less. conversion material.
The wavelength conversion member according to any one of claims 1 to 7, wherein the excitation light is UV light.
The wavelength conversion member according to any one of claims 1 to 8, wherein the fluorescence is visible light.
a light source that emits excitation light;
A wavelength conversion member according to any one of claims 1 to 9;
A light emitting device comprising: