Wavelength conversion member and light-emitting device

Abstract

To provide a wavelength conversion member with which it is possible to efficiently excite a phosphor when ultraviolet light is used as excitation light, and suppress the degradation of peripheral members and the effect on human body due to the leakage of the ultraviolet light.SOLUTION: Provided is a wavelength conversion member 1 for converting the wavelength of excitation light emitted from a light source 7, comprising: a first layer 2 composed of a first glass matrix 4 and phosphor particles 5 dispersed 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. The first layer 2 is provided on the light source 7 side, and a difference |TA-TB| between a transmittance TA of the first glass matrix 4 and a transmittance TB of the second glass matrix 6 at an excitation wavelength is larger than a difference |LA-LB| between a transmittance LA of the first glass matrix 4 and a transmittance LB of the second glass matrix 6 at a fluorescent wavelength and TA>TB is satisfied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wavelength conversion member that converts the wavelength of light emitted from a light emitting diode (LED) or a laser diode (LD) into another wavelength, and a light emitting device using the wavelength conversion member.

Background Art

[0002] In recent years, as a next-generation light emitting device to replace fluorescent lamps and incandescent lamps, attention has been increasing for light emitting devices using LEDs and LDs from the viewpoints of low power consumption, small size and light weight, and easy light amount adjustment. As an example of such a light emitting device, for example, Patent Document 1 below discloses a light emitting device in which a wavelength conversion member that absorbs part of the light from an LED and converts it into yellow light is disposed on an LED that emits blue light. This light emitting device emits white light, which is a synthesized light of blue light emitted from the LED and yellow light emitted from the wavelength conversion member.

[0003] As light emitting devices using LEDs and LDs, not only for general lighting applications, but also sensing light emitting devices 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 including a light emitting element that emits ultraviolet light and / or visible light, and a phosphor layer provided on the light emitting element.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the excitation light leaks to the outside together with fluorescence, it may have an adverse effect on the function as a sensor. Furthermore, ultraviolet light is likely to have an adverse effect on the human body when its wavelength is short. Therefore, in the light-emitting device described in Patent Document 2, a filter that does not transmit the excitation light but only transmits fluorescence is formed on the surface of the phosphor layer. However, forming such a filter on the surface of the phosphor layer has a problem that the manufacturing process becomes complicated and the cost increases.

[0006] In view of the above, an object of the present invention is to provide a wavelength conversion member that can efficiently excite a phosphor even when ultraviolet light is used as excitation light, and can suppress deterioration of peripheral members and influence on the human body due to leakage of ultraviolet light, and a light-emitting device using the wavelength conversion member.

Means for Solving the Problems

[0007] The 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 is composed of a first glass matrix and phosphor particles dispersed in the first glass matrix. a first layer, and a second layer provided on the first layer and composed of a second glass matrix, wherein the first layer is provided on the light source side, and the transmittance T of the first glass matrix at the excitation wavelength A and the transmittance T of the second glass matrix B The difference |T A -T B | is the transmittance L of the first glass matrix at the fluorescence wavelength A and the transmittance L of the second glass matrix B The difference |L A -L B | and is larger than, and T A >T B It is characterized by being.

[0008] In the present invention, the difference between the transmittance difference at the excitation wavelength and the transmittance difference at the fluorescence wavelength |T A -T B |-|LA -L B It is preferably 20% or more.

[0009] In the present invention, the transmittance T at the excitation wavelength of the first glass matrix A is 20% or more, and the transmittance T at the excitation wavelength of the second glass matrix B is preferably 65% or less.

[0010] In the present invention, the transmittance L at the fluorescence wavelength of the first glass matrix A is 50% or more, and the transmittance L at the fluorescence wavelength of the second glass matrix B is preferably 50% or more.

[0011] In the present invention, it is preferable that the second layer substantially does not contain phosphor particles.

[0012] In the present invention, it is preferable that the thickness of the second layer is larger than the thickness of the first layer.

[0013] In the present invention, the ratio of the thickness of the second layer to the first layer (second layer / first layer) is preferably 1 or more and 30 or less.

[0014] In the present invention, the excitation light is preferably UV light.

[0015] In the present invention, the fluorescence is preferably visible light.

[0016] The light-emitting device according to the present invention is characterized by including a light source that emits excitation light and a wavelength conversion member configured according to the present invention.

Advantages of the Invention

[0017] According to the present invention, even when UV light is used as excitation light, the phosphor can be efficiently excited, and moreover, deterioration of peripheral members and influence on the human body due to leakage of UV light can be suppressed without using an external filter. A wavelength conversion member and a light-emitting device using the wavelength conversion member can be provided.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0019] Hereinafter, preferred embodiments will be described. However, the following embodiments are merely illustrative, 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.

[0020] [Wavelength Conversion Member] FIG. 1 is a schematic front cross-sectional view showing a wavelength conversion member according to an embodiment of the present invention. As shown in FIG. 1, the wavelength conversion member 1 of the present embodiment has a rectangular plate shape. However, the wavelength conversion member 1 may have a substantially disc shape, and its shape is not particularly limited.

[0021] The wavelength conversion member 1 includes a first layer 2 and a second layer 3. The first layer 2 has a first main surface 2a and a second main surface 2b. The second layer 3 is provided on the first main surface 2a of the first layer 2. Also, the second main surface 2b of the first layer 2 is the surface on the side where the light source 7 is provided. Therefore, the second layer 3 is provided on the side opposite to the light source 7 side.

[0022] The first layer 2 is a phosphor glass composed of a first glass matrix 4 and phosphor particles 5. In the present 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.

[0023] In the present embodiment, as shown in FIG. 1, the excitation light A from the light source 7 is emitted to the wavelength conversion member 1. The excitation light A enters the first layer 2 from the second main surface 2b side. When the excitation light A irradiates the first layer 2 where the phosphor is disposed, fluorescence B is emitted. The fluorescence B passes through the second layer 3 and is emitted from the wavelength conversion member 1.

[0024] FIG. 2 is a diagram showing an example of the transmittance spectra of the first glass matrix 4 and the second glass matrix 6 that constitute such a wavelength conversion member 1. In FIG. 2, the individual transmittance spectra of the first glass matrix 4 and the second glass matrix 6 are shown. The transmittance spectra of the first glass matrix 4 and the second glass matrix 6 are each measured for a glass plate with a thickness of 1 mm. This glass plate is obtained by vacuum firing a compact of glass powder (average particle diameter 2.5 μm), which is the raw material of the first glass matrix 4 or the second glass matrix 6, at a temperature 50°C above the softening point of the glass powder to obtain a sintered body, and then subjecting the obtained sintered body to cutting, lapping, and polishing processes so that the thickness becomes 1 mm. The transmittance shown in this patent represents the total light transmittance in the polished sintered body with 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 by a spectrophotometer.

[0025] As shown in FIG. 2, in this embodiment, the transmittance T of the first glass matrix 4 at the excitation wavelength A and the transmittance T of the second glass matrix 6 B The absolute value of the difference |T A -T B | is the transmittance L of the first glass matrix 4 at the fluorescence wavelength A and the transmittance L of the second glass matrix 6 B The absolute value of the difference |L A -L B | is larger. More specifically, at the excitation wavelength, the transmittance T of the first glass matrix 4 A is larger than the transmittance T of the second glass matrix 6 B . On the other hand, at the fluorescence wavelength, the transmittance L of the first glass matrix 4 A and the transmittance L of the second glass matrix 6 BBoth 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 maximum, and the fluorescence wavelength means the wavelength at which the fluorescence intensity is maximum. In this embodiment, the transmittance of the excitation wavelength refers to the transmittance of UV light, specifically, the transmittance at wavelengths from 200 nm to 380 nm. Also, the transmittance of the fluorescence wavelength refers to the transmittance of visible light, specifically, the transmittance at wavelengths from 380 nm to 800 nm.

[0026] When UV light as 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, since the transmittance of the first glass matrix 4 constituting the first layer 2 at the excitation wavelength is high, the absorption of the excitation light A by the glass can be reduced, and wavelength conversion to fluorescence can be efficiently performed in the first layer 2. On the other hand, in the second layer 3, since the transmittance of the second glass matrix 6 constituting the second layer 3 at the excitation wavelength is low, the UV light which is the excitation light A can be shielded in the second layer 3. Therefore, deterioration of peripheral members and influence on the human body due to leakage of UV light can be suppressed. Also, since the transmittances of the first glass matrix 4 and the second glass matrix 6 constituting the first layer 2 and the second layer 3 at the fluorescence wavelength are high, fluorescence can be efficiently emitted. Thus, according to the wavelength conversion member 1 of this embodiment, even when UV light is used as the excitation light A, the phosphor can be efficiently excited, and moreover, deterioration of peripheral members and influence on the human body due to leakage of UV light can be suppressed.

[0027] 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 40% or more, still more preferably 60% or more, and particularly preferably 75% or more. The difference |T A -T B |-|L A -L BWhen | is equal to or greater than the above lower limit value, the phosphor can be excited more efficiently, and moreover, deterioration of peripheral members due to leakage of UV light and influence on the human body can be further suppressed. Note that the above difference |T A -T B |-|L A -L B The upper limit value of | is not particularly limited, but for example, it can be set to 95%.

[0028] 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 UV light can be more reliably shielded, and the fluorescence emission efficiency can be further increased.

[0029] 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, still more preferably 2 or more, preferably 30 or less, more preferably 10 or less, and still more preferably 7 or less. When the above thickness ratio (second layer 3 / first layer 2) is equal to or greater than the above lower limit value, the UV light can be more reliably shielded, and the fluorescence emission efficiency can be further increased. On the other hand, when the above thickness ratio (second layer 3 / first layer 2) is equal to or less than the above upper limit value, the light emission intensity of the wavelength conversion member can be further increased.

[0030] Note that 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. 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, and 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 value, the light emission intensity and mechanical strength of the wavelength conversion member 1 can be further increased. Also, when the thickness of the wavelength conversion member 1 is equal to or less than the above upper limit value, light scattering and absorption in the wavelength conversion member 1 can be further suppressed, and the fluorescence emission efficiency can be further increased.

[0031] Also, as described later, since the first glass matrix 4 and the second glass matrix 6 are basically produced by laminating green sheets as raw materials for each layer and firing them simultaneously, it is preferable that 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 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, still more preferably 50 °C or less, and particularly preferably 10 °C or less. Most preferably, the softening points of both are the same.

[0032] (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.

[0033] First glass matrix; The first glass matrix 4 is composed of a glass that can be used as a dispersion medium for phosphor particles 5 such as inorganic phosphors. Also, the first glass matrix 4 is composed of a glass (UV light transmitting glass) that transmits UV light and fluorescence.

[0034] Transmittance T at the excitation wavelength of the first glass matrix 4 A is preferably 20% or more, more preferably 40% or more, still more preferably 60% or more, and particularly preferably 80% or more. When the transmittance T at the excitation wavelength of the first glass matrix 4 A is equal to or higher than the above lower limit value, the absorption of excitation light by the glass can be further reduced, and fluorescence can be emitted more efficiently in the first layer 2. The upper limit value of the transmittance T at the excitation wavelength of the first glass matrix 4 A is not particularly limited, but can be, for example, 95%.

[0035] Transmittance L at the fluorescence wavelength of the first glass matrix 4 Ais preferably 50% or more, more preferably 75% or more, and even more preferably 80% or more. The transmittance L at the fluorescence wavelength of the first glass matrix 4 A When it is equal to or higher than the above lower limit value, fluorescence can be emitted more efficiently in the first layer 2. The transmittance L at the fluorescence wavelength of the first glass matrix 4 A The upper limit value is not particularly limited, and for example, it can be 95%.

[0036] The glass constituting the first glass matrix 4 is not particularly limited as long as it has the above-described optical properties. For example, borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, and tellurite glass can be used.

[0037] As a specific example of the glass constituting the first glass matrix 4, for example, in mol%, SiO2 40% to 60%, B2O3 0.1% to 35%, Al2O3 0.1% to 10%, Li2O 0% to 10%, Na2O 0% to 10%, K2O 0% to 10%, Li2O + Na2O + K2O 0.1% to 10%, MgO 0% to 45%, CaO 0% to 45%, SrO 0% to 45%, BaO 0% to 45%, MgO + CaO + SrO + BaO 0.1% to 45%, and ZnO 0% to 15% can be used.

[0038] The glass constituting the first glass matrix 4 may be a glass containing, by mass%, SiO2 55% to 75%, Al2O3 1% to 10%, B2O3 10% to 30%, CaO 0% to 5%, BaO 0% to 5%, and Li2O + Na2O + K2O 1% to 15%.

[0039] Further, the glass constituting the first glass matrix 4 may be a glass containing, by mass%, SiO2 + B2O3 60% to 90%, Li2O + Na2O + K2O 0% to 20%, and MgO + CaO + SrO + BaO 0% to 20%.

[0040] When the glass constituting the first glass matrix 4 contains Fe2O3 or TiO2, the transmittance of UV light tends to decrease. Therefore, these contents are preferably low and preferably not substantially contained. Here, "not substantially contained" means a raw material that is not intentionally contained, and objectively refers to less than 1000 ppm.

[0041] In this specification, "x + y + ···" means the total content of each component.

[0042] The softening point of the first glass matrix 4 is preferably 250°C to 1000°C, more preferably 300°C to 950°C, and 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 decrease. Also, since the heat resistance of the first glass matrix 4 itself is low, there is a risk of softening and deformation due to the heat generated from the phosphor particles 5. On the other hand, if the softening point of the first glass matrix 4 is too high, when the manufacturing process includes a firing step, the phosphor particles 5 may deteriorate and the emission intensity of the wavelength conversion member 1 may decrease. 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 even more preferably 650°C or higher. However, when the softening point of the first glass matrix 4 increases, the firing temperature also increases, and as a result, the manufacturing cost tends to increase. Also, when the heat resistance of the phosphor particles 5 is low, there is a risk of deterioration due to firing. Therefore, when manufacturing the wavelength conversion member 1 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 lower, more preferably 530°C or lower, even more preferably 500°C or lower, particularly preferably 480°C or lower, and most preferably 460°C or lower.

[0043] Phosphor particles; The phosphor particles 5 are not particularly limited as long as they emit fluorescence upon incidence of excitation light. Examples of the phosphor particles 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, or garnet-based compound phosphors, etc. These phosphors may be used individually by one kind, or may be used in combination of plural kinds. Examples of the phosphor that absorbs UV light and emits visible light include, for example, Lu3Al5O 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), La3Si6N 11 :Ce(fluorescence wavelength 535 nm), etc.

[0044] The average particle diameter of the phosphor particles 5 is preferably 1 μm or more, more preferably 5 μm or more. When the average particle diameter 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, when the average particle diameter of the phosphor particles 5 is too large, the dispersion state in the first glass matrix 4 tends to deteriorate and the emission color tends to become non-uniform. Therefore, the average particle diameter of the phosphor particles 5 is preferably 50 μm or less, more preferably 25 μm or less.

[0045] In this specification, the average particle diameter refers to the average particle diameter D 50 measured by a laser diffraction particle size distribution measuring device.

[0046] 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 still 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 still 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 to obtain the desired fluorescence intensity. As a result, the internal scattering and matrix absorption of the wavelength conversion member 1 increase, and the light extraction efficiency may decrease. On the other hand, if the content of the phosphor particles 5 is too large, the proportion of glass relatively decreases, and the force of the glass to support the phosphor becomes weak, so the mechanical strength of the wavelength conversion member 1 may decrease.

[0047] In the present embodiment, the second glass matrix 6 is composed of a powder sintered body of only glass powder, but is not limited thereto. For example, the second glass matrix 6 may contain other inorganic powders such as filler powders for the purpose of adjusting the thermal expansion coefficient and obtaining a light scattering effect. In this way, the thermal expansion coefficients of the first layer 2 and the second layer 3 can be easily matched, and the occurrence of warping, cracks, etc. of the wavelength conversion member 1 due to the difference in thermal expansion coefficient can be further suppressed. In addition, due to the light scattering effect of the filler powder, the emission intensity of the wavelength conversion member 1 can be further improved. Furthermore, by containing a filler powder with high thermal conductivity, the heat dissipation efficiency of the wavelength conversion member 1 can be further improved. Examples of the filler powder include MgO, Al2O3, BN, AlN, etc. Among them, MgO, Al2O3, and BN are preferable because of their excellent transmittance in the visible region.

[0048] The 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. When the thickness of the first layer 2 is equal to or greater than the above lower limit value, the light emission intensity and mechanical strength of the wavelength conversion member 1 can be further enhanced. Further, when the thickness of the first layer 2 is equal to or less than the above upper limit value, light scattering and absorption in the first layer 2 can be further suppressed, and the fluorescence emission efficiency can be further enhanced.

[0049] (The second layer) The second layer 3 is composed of a second glass matrix 6. The second glass matrix 6 is composed of a glass (such as a UV light shielding glass) that shields excitation light (for example, UV light) and transmits fluorescence.

[0050] The transmittance T at the excitation wavelength of the second glass matrix 6 B is preferably 65% or less, more preferably 40% or less, still more preferably 20% or less, and particularly preferably 10% or less. When the transmittance T at the excitation wavelength of the second glass matrix 6 B is equal to or less than the above upper limit value, the excitation light can be more reliably shielded in the second layer 3, and for example, when the excitation light is UV light, deterioration of peripheral members and effects on the human body due to its leakage can be more reliably suppressed. The lower limit value of the transmittance T at the excitation wavelength of the second glass matrix 6 B is not particularly limited, but can be, for example, 0%.

[0051] The transmittance L at the fluorescence wavelength of the second glass matrix 6 B is preferably 50% or more, more preferably 75% or more, still more preferably 80% or more. When the transmittance L at the fluorescence wavelength of the second glass matrix 6 B is equal to or greater than the above lower limit value, fluorescence can be more efficiently emitted in the wavelength conversion member 1. The transmittance L at the fluorescence wavelength of the second glass matrix 6 BThe upper limit value is not particularly limited and can be, for example, 95%.

[0052] The glass constituting the second glass matrix 6 is not particularly limited as long as it has the above-described optical properties. For example, borosilicate glass, phosphate glass, tin phosphate glass, bismuthate glass, and tellurite glass can be used.

[0053] As a specific example of the glass constituting the second glass matrix 6, for example, in mol%, a glass containing 40% to 60% of SiO2, 0.1% to 35% of B2O3, 0.1% to 10% of Al2O3, 0% to 10% of Li2O, 0% to 10% of Na2O, 0% to 10% of K2O, 0.1% to 10% of Li2O + Na2O + K2O, 0% to 45% of MgO, 0% to 45% of CaO, 0% to 45% of SrO, 0% to 45% of BaO, 0.1% to 45% of MgO + CaO + SrO + BaO, 0% to 15% of ZnO, and 0.001% to 10% of CeO2 can be used.

[0054] The glass constituting the second glass matrix 6 may be a glass containing 30% to 85% of SiO2, 0% to 30% of Al2O3, 0% to 50% of B2O3, 0% to 10% of Li2O + Na2O + K2O, and 0% to 50% of MgO + CaO + SrO + BaO by mass%.

[0055] The softening point of the second glass matrix 6 is preferably 250°C to 1000°C, more preferably 300°C to 950°C, and 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 decrease. On the other hand, if the softening point of the second glass matrix 6 is too high, when the firing process is included during manufacturing, the phosphor particles 5 may deteriorate and the light emission intensity of the wavelength conversion member 1 may decrease.

[0056] The 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 equal to or greater than the above lower limit value, the excitation light can be more reliably shielded in the second layer 3. For example, when the excitation light is UV light, the deterioration of peripheral members and the influence on the human body due to its leakage can be more reliably suppressed. Further, when the thickness of the second layer 3 is equal to or less than the above upper limit value, the light scattering and absorption in the second layer 3 can be further suppressed, and the fluorescence emission efficiency can be further increased.

[0057] The second layer 3 desirably does not substantially contain phosphor particles. However, the second layer 3 may contain phosphor particles.

[0058] (Method for manufacturing wavelength conversion member) Hereinafter, an example of a method for manufacturing a wavelength conversion member will be described.

[0059] First, a green sheet for forming the first layer is prepared. Specifically, a slurry containing glass particles that will become the first glass matrix 4 and phosphor particles 5 is prepared. Usually, a binder resin and a solvent are contained in the above slurry. Subsequently, the prepared slurry is applied onto a support substrate, and a doctor blade installed at a predetermined interval from the substrate is relatively moved with respect to the slurry to form a green sheet for forming the first layer. As the above support substrate, for example, a resin film such as polyethylene terephthalate can be used.

[0060] Next, a green sheet for forming the second layer is prepared. Specifically, a slurry containing glass particles that will become the second glass matrix 6 is prepared, and a green sheet for forming the second layer is obtained in the same manner as above.

[0061] Note that, as the materials of the glass particles that form the first glass matrix 4 and the second glass matrix 6, the same materials as those of the first glass matrix 4 and the second glass matrix 6 described above can be used. Also, the average particle diameter of the glass particles is preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 2 μm or more. If the average particle diameter 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 diameter of the glass particles is too large, in the obtained wavelength conversion member 1, bubbles are likely to remain in the glass matrix after firing, and the light extraction efficiency of the wavelength conversion member 1 may decrease. Therefore, the average particle diameter 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. Also, the average particle diameter of the phosphor particles is desirably within the range described in the first layer 2 above.

[0062] Next, the green sheet for forming the first layer and the green sheet for forming the second layer are laminated by thermocompression bonding or the like to obtain a laminate. Subsequently, the laminate is fired at a temperature of about the softening point of the glass particles to the softening point of the glass particles + 100 °C, whereby the wavelength conversion member 1 composed of a sintered body in which the first layer 2 and the second layer 3 are laminated can be obtained. The above firing is preferably performed in a reduced-pressure atmosphere, and more preferably performed in a vacuum atmosphere. In this case, a wavelength conversion member 1 having even better denseness can be obtained. Also, it is preferable to fire the laminate while sandwiching it between a pair of restraint members. In this case, the flatness of the wavelength conversion member 1 (particularly, the flatness of the interface between the first layer 2 and the second layer 3) is improved, and it becomes easier to process it to a desired thickness in the subsequent polishing process. Note that, before firing, it is preferable to perform a debinding treatment at a temperature lower than the softening point of the glass particles. In this case, in the obtained wavelength conversion member 1, the residue of organic components that cause light absorption and scattering can be reduced, and the light emission intensity can be further improved.

[0063] Further, it is preferable to polish the first layer 2 in the obtained sintered body to a desired thickness. Specifically, it is preferable to polish the first layer 2 in the sintered body to a predetermined thickness to adjust the chromaticity of the wavelength conversion member 1. The second layer 3 in the obtained sintered body may be polished to a desired thickness.

[0064] Note that the manufacturing method of the wavelength conversion member 1 is not limited to the above method. For example, after separately firing the green sheet for forming the first layer and the green sheet for forming the second layer, the obtained fired bodies may be joined by thermocompression bonding or an adhesive to obtain the wavelength conversion member 1.

[0065] [Light-emitting device] FIG. 3 is a schematic front cross-sectional view showing a light-emitting device according to an embodiment of the present invention. As shown in FIG. 3, the light-emitting device 11 includes the wavelength conversion member 1 according to the above-described embodiment 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 such that the excitation light A directly enters the wavelength conversion member 1 from the side of the first layer 2.

[0066] Also in the wavelength conversion member 1 of the light-emitting device 11, by providing the first layer 2 and the second layer 3, it is possible to efficiently excite the phosphor and suppress the deterioration of peripheral members and the influence on the human body due to the leakage of UV light.

[0067] Note that the arrangement of the light source 7 is not limited to the above. For example, in the modification 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 such that the excitation light A directly enters 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 face of the light guide plate 12, exits from the main face 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.

[0068] The light-emitting device 11 can be suitably used, for example, as a light-emitting device for sensing or for high-color-rendering illumination.

[0069] Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be implemented with appropriate modifications without changing the gist thereof.

[0070] (Example 1) As glass particles serving as the first glass matrix, glass particles A having a composition of 45% SiO2, 4% Al2O3, 18% B2O3, 1.5% Li2O, 1.5% Na2O, 1.5% K2O, 25% BaO, and 3.5% ZnO in mol% (softening point: 690 °C, thermal expansion coefficient: 86.1×10 -7 / °C, average particle diameter: 2.5 μm) were prepared.

[0071] Next, glass particles A, phosphor particles (Lu3Al5O 12 , average particle diameter: 15 μm), a binder resin (manufactured by Kyoeisha Chemical Co., Ltd., Oricox), a plasticizer (dioctyl adipate), a dispersant (manufactured by Kyoeisha Chemical Co., Ltd., Floren G-700), and an organic solvent (methyl ethyl ketone) were kneaded to obtain a slurry-like mixture. The obtained slurry-like mixture was formed into a sheet by the doctor blade method and dried at room temperature to obtain a green sheet for forming the first layer. The addition amount of the phosphor particles was adjusted to be 30% by volume in the first layer.

[0072] Next, as glass particles serving as the second glass matrix, glass particles X having a composition of 45% SiO2, 4% Al2O3, 18% B2O3, 1.5% Li2O, 1.5% Na2O, 1.5% K2O, 25% BaO, 3% ZnO, and 0.5% CeO2 in mol% (softening point: 690 °C, thermal expansion coefficient: 86.1×10 -7 / °C, average particle diameter: 2.5 μm) were prepared.

[0073] Next, glass particles X, a binder resin (manufactured by Koei Chemical Co., Ltd., Orinox), a plasticizer (dioctyl adipate), a dispersant (manufactured by Koei Chemical Co., Ltd., Floren G-700), and an organic solvent (methyl ethyl ketone) were kneaded to obtain a slurry-like mixture. The obtained slurry-like mixture was formed into a sheet by the doctor blade method and dried at room temperature to obtain a green sheet for forming the second layer.

[0074] Next, after cutting the green sheet for forming the first layer and the green sheet for forming the second layer into a predetermined size, both were thermocompression-bonded. The obtained laminate was subjected to a debinding treatment in an electric furnace, and then vacuum firing was carried out at 740 °C (the softening point of the glass particles that become the first glass matrix and the glass particles that become the second glass matrix + 50 °C) in a vacuum gas replacement furnace. The obtained fired body was polished on each side so as to have a desired layer thickness, thereby obtaining a wavelength conversion member in which the first layer and the second layer were laminated. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

[0075] (Example 2) As the glass particles that become the first glass matrix, glass particles B having a composition of 68% SiO2, 4% Al2O3, 19% B2O3, 7% Na2O, 1% K2O, and 1% F2 by mass% (softening point: 700 °C, thermal expansion coefficient: 41.9×10 -7 / °C, average particle diameter: 2.5 μm) were prepared.

[0076] Also, as the glass particles that become the second glass matrix, glass particles Y having a composition of 50% SiO2, 6% Al2O3, 5% B2O3, 12% CaO, 25% BaO, and 2% ZnO by mass% (softening point: 850 °C, thermal expansion coefficient: 68.0×10 -7 / °C, average particle diameter: 2.5 μm) were prepared.

[0077] Also, vacuum firing was carried out at 900 °C (the higher softening point of the glass particles that become the first glass matrix and the glass particles that become the second glass matrix + 50 °C).

[0078] For other points, in the same manner as in Example 1, a wavelength conversion member was obtained. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

[0079] (Example 3) As the glass particles serving as the first glass matrix, glass particles C having a composition of 71% SiO2, 6% Al2O3, 13% B2O3, 7% Na2O, 1% K2O, 1% CaO, and 1% BaO by mass% (softening point: 737 °C, thermal expansion coefficient: 66.0×10 -7 / °C, average particle diameter: 2.5 μm) were prepared.

[0080] Also, as the glass particles serving as the second glass matrix, the same glass particles Y as in Example 2 were prepared.

[0081] Also, vacuum firing was carried out at 900 °C (the higher softening point of the glass particles serving as the first glass matrix and the glass particles serving as the second glass matrix + 50 °C).

[0082] For other points, in the same manner as in Example 1, a wavelength conversion member was obtained. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

[0083] In addition, the measurement results of the transmittance at a wavelength of 250 nm (UV-C transmittance), the transmittance at a wavelength of 280 nm (transmittance at the excitation wavelength), 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 the fluorescence wavelength) of each of the first glass matrix and the second glass matrix used in Examples 1 to 3 are shown in Table 1 below. The transmittance of the first glass matrix and the second glass matrix was measured for a glass plate with a thickness of 1 mm. This glass plate was produced by the method described above. Also, the transmittance of the first glass matrix and the second glass matrix was measured using a spectrophotometer (manufactured by JASCO Corporation, model number V-670).

[0084]

Table 1

[0085] (Comparative Example 1) As the glass particles serving as the first glass matrix, the same glass particles X as the second glass matrix in Example 1 were prepared.

[0086] Next, a slurry-like mixture was obtained by kneading glass particles X, phosphor particles (Lu3Al5O 12 , average particle diameter: 15 μm), a binder resin (manufactured by Kyoeisha Chemical Co., Ltd., Orinox), a plasticizer (dioctyl adipate), a dispersant (manufactured by Kyoeisha Chemical Co., Ltd., Floren G-700), and an organic solvent (methyl ethyl ketone). The obtained slurry-like mixture was formed into a sheet by the doctor blade method and dried at room temperature to obtain a green sheet. The addition amount of the phosphor particles was adjusted to be 6% by volume in the resulting wavelength conversion member.

[0087] Next, the obtained green sheet was subjected to a debinding treatment in an electric furnace, and then vacuum firing was carried out at 740 °C in a vacuum gas replacement furnace. The obtained fired body was polished to have a desired layer thickness to obtain a wavelength conversion member composed of only the first layer. The thickness of the wavelength conversion member was 200 μm.

[0088] (Comparative Example 2) As the glass particles serving as the first glass matrix, the same glass particles A as the first glass matrix in Example 1 were prepared. In other respects, in the same manner as in Comparative Example 1, a wavelength conversion member composed of only the first layer was obtained. The thickness of the wavelength conversion member was 200 μm.

[0089] (Comparative Example 3) As the glass particles serving as the first glass matrix, the same glass particles A as the first glass matrix in Example 1 were prepared.

[0090] Also, as the glass particles that form the second glass matrix, the same glass particles B as those of the first glass matrix in Example 2 were prepared.

[0091] Also, vacuum firing was carried out at 750 °C (the higher softening point of the glass particles that form the first glass matrix and the glass particles that form the second glass matrix + 50 °C).

[0092] In other respects, a wavelength conversion member was obtained in the same manner as in Example 1. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

[0093] (Comparative Example 4) As the glass particles that form the first glass matrix, the same glass particles X as those of the second glass matrix in Example 1 were prepared.

[0094] Also, as the glass particles that form the second glass matrix, the same glass particles Y as those of the second glass matrix in Example 2 were prepared.

[0095] Also, vacuum firing was carried out at 900 °C (the higher softening point of the glass particles that form the first glass matrix and the glass particles that form the second glass matrix + 50 °C).

[0096] In other respects, a wavelength conversion member was obtained in the same manner as in Example 1. The thickness of the first layer was 40 μm, and the thickness of the second layer was 160 μm.

[0097] (Evaluation) First, the energy distribution spectrum of a UVLED (λp = 280 nm) as an excitation light source was measured using a luminescence spectrum measuring device (manufactured by Ocean Photonics). The peak intensity at this time was designated as I1.

[0098] Next, for each of the wavelength conversion members produced in Examples 1 to 3 and Comparative Examples 1 to 4, a UV LED (λp = 280 nm) was irradiated, and the energy distribution spectrum of the light emitted from the emission surface side of the wavelength conversion member was measured using the same emission spectrum measuring device (manufactured by Ocean Photonics). As shown in an example 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 defined as I3 and measured. The ratios of the measured I2 to I1 (I2 / I1) and I3 to I1 (I3 / I1) are shown in Table 2 below.

[0099]

Table 2

[0100] From Table 2, it can be seen that in the wavelength conversion members of Examples 1 to 3, the ratio (I2 / I1) is small, indicating that the UV light can be sufficiently shielded. Also, in the wavelength conversion members of Examples 1 to 3, the ratio (I3 / I1) is large, indicating that the phosphor can be efficiently excited.

[0101] On the other hand, in the wavelength conversion members of Comparative Examples 1 and 4, the ratio (I3 / I1) was small, and the phosphor could not be efficiently excited. Also, in the wavelength conversion members of Comparative Examples 2 and 3, the ratio (I2 / I1) was large, and the UV light could not be sufficiently shielded.

[0102] 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 larger than the transmittance difference |L A -L B | between the first glass matrix and the second glass matrix at the fluorescence wavelength, and T A >T B In the wavelength conversion members of Examples 1 to 3 which satisfy the above conditions, even when UV light is used as the excitation light, it was confirmed that the phosphor can be efficiently excited, and moreover, deterioration of peripheral members and influence on the human body due to leakage of UV light can be suppressed without using an external filter.

Explanation of symbols

[0103] 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

1. A wavelength conversion member for converting the wavelength of excitation light emitted from a light source, comprising: 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; wherein the first layer is provided on the light source side; Transmittance T of the first glass matrix at the excitation wavelength Ａ and transmittance T of the second glass matrix Ｂ The difference |T Ａ −T Ｂ | is greater than the difference |L Ａ between the transmittance L of the first glass matrix and the transmittance L of the second glass matrix at the fluorescence wavelength Ｂ |, and T Ａ > T Ｂ |, and Ａ T Ｂ is true, the wavelength conversion member in which the difference |TA−TB|−|LA−LB| between the transmittance difference at the excitation wavelength and the transmittance difference at the fluorescence wavelength is 20% or more.

2. A wavelength conversion member for converting the wavelength of excitation light emitted from a light source, comprising: 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; wherein the first layer is provided on the light source side; the difference |TA−TB| between the transmittance TA of the first glass matrix and the transmittance TB of the second glass matrix at the excitation wavelength is larger than the difference |LA−LB| between the transmittance LA of the first glass matrix and the transmittance LB of the second glass matrix at the fluorescence wavelength, and TA>TB. Transmittance T at the excitation wavelength of the first glass matrix Ａ is 20% or more, and the transmittance T at the excitation wavelength of the second glass matrix Ｂ is 65% or less, a wavelength conversion member.

3. The transmittance L at the fluorescence wavelength of the first glass matrix Ａ is 50% or more, and the transmittance L at the fluorescence wavelength of the second glass matrix Ｂ is 50% or more. The wavelength conversion member according to claim 1 or 2

4. The wavelength conversion member according to any one of claims 1 to 3, wherein the second layer substantially does not contain phosphor particles.

5. The wavelength conversion member according to any one of claims 1 to 4, wherein the thickness of the second layer is larger than the thickness of the first layer.

6. The wavelength conversion member according to any one of claims 1 to 5, wherein the ratio of the thickness of the second layer to the thickness of the first layer (second layer / first layer) is 1 or more and 30 or less.

7. The wavelength conversion member according to any one of claims 1 to 6, wherein the excitation light is UV light.

8. The wavelength conversion member according to any one of claims 1 to 7, wherein the fluorescence is visible light.

9. The wavelength conversion member according to any one of claims 1 to 8, wherein the second glass matrix is composed of a glass containing, in mol%, 40% to 60% of SiO₂, 0.1% to 35% of B₂O₃, 0.1% to 10% of Al₂O₃, 0% to 10% of Li₂O, 0% to 10% of Na₂O, 0% to 10% of K₂O, 0.1% to 10% of Li₂O + Na₂O + K₂O, 0% to 45% of MgO, 0% to 45% of CaO, 0% to 45% of SrO, 0% to 45% of BaO, 0.1% to 45% of MgO + CaO + SrO + BaO, 0% to 15% of ZnO, and 0.001% to 10% of CeO₂.

10. The wavelength conversion member according to any one of claims 1 to 8, wherein the second glass matrix is composed of a glass containing, in mass%, 30% to 85% of SiO₂, 0% to 30% of Al₂O₃, 0% to 50% of B₂O₃, 0% to 10% of Li₂O + Na₂O + K₂O, and 0% to 50% of MgO + CaO + SrO + BaO.

11. A light source that emits excitation light, The wavelength conversion member according to any one of claims 1 to 10, A light emitting device comprising the same.

Images