WO2011111462A1 - Wavelength conversion member, optical device, and process for production of wavelength conversion member - Google Patents

Abstract

Disclosed is a wavelength conversion member comprising an inorganic phosphor powder dispersed in a glass matrix and can have high light emission efficiency. The wavelength conversion member comprises a glass matrix, an inorganic phosphor powder dispersed in the glass matrix, and an intermediate layer, wherein the intermediate layer is arranged at the interface between the inorganic phosphor powder and the glass matrix, comprises a reaction product of the inorganic phosphor powder with the glass matrix, and has a thickness of 0.01 to 5 μm.

Description

Wavelength conversion member, optical device, and method of manufacturing wavelength conversion member

The present invention relates to a wavelength conversion member used as a constituent member such as a white LED (Light Emitting Diode), an optical device using the same, and a method of manufacturing the wavelength conversion member.

In recent years, white LEDs have been actively developed. The white LED is composed of, for example, an LED that emits blue or ultraviolet excitation light, and a wavelength conversion member in which inorganic phosphor powder is dispersed in a matrix such as a resin. The inorganic phosphor powder receives the excitation light from the LED and emits light (fluorescence) having a wavelength different from that of the excitation light. On the other hand, a part of the excitation light from the LED does not contribute to wavelength conversion and passes through the wavelength conversion member. These lights are mixed to obtain white light.

White LEDs are characterized by low power consumption and long life compared to incandescent and fluorescent lamps. For this reason, white LEDs are being used as backlights for mobile phones and digital cameras. In the future, white LEDs are expected to be applied to lighting applications as next-generation light sources that replace incandescent and fluorescent lamps.

By the way, white LEDs are required to have higher brightness (higher power) depending on the application. For this reason, the conventional method of dispersing the inorganic phosphor powder in the resin matrix has a problem that the resin matrix is discolored by heat from the LED and the luminance is lowered when used for a long time. In addition, when a resin containing an inorganic phosphor powder is applied onto an LED, the thickness tends to vary, and the light distribution may be lowered.

In order to solve these problems, a method has been proposed in which inorganic phosphor powder is dispersed in a glass matrix and the wavelength conversion member is completely mineralized (see, for example, Patent Documents 1 and 2). According to this method, the heat resistance and weather resistance of the wavelength conversion member can be improved. Specifically, even when exposed to a high temperature environment (for example, 150 ° C., 600 hours) or a high temperature / humidity environment (for example, 2000 hours, temperature 85 ° C., humidity 85%) for a long time, the white LED has almost no light emission characteristics. It does not change, and there is almost no coloring or deterioration even if it is exposed to ultraviolet rays of sunlight for a long time. Furthermore, since it is excellent in workability, it is possible to suppress a decrease in light distribution due to thickness variation.

JP 2005-11933 A Japanese Patent No. 4158012

Although the wavelength conversion member formed by dispersing the inorganic phosphor powder in the glass matrix is superior in long-term stability compared to the wavelength conversion member using the resin matrix, the conventional inorganic phosphor powder is dispersed in the glass matrix. In such a wavelength conversion member, light loss due to reflection or scattering at the interface between the inorganic phosphor powder and the glass matrix is large. For this reason, it is difficult to sufficiently increase the luminous efficiency. The reflection and scattering at the interface between the inorganic phosphor powder and the glass matrix are caused by the difference in refractive index between the inorganic phosphor powder and the glass matrix.

Therefore, an object of the present invention is to provide a wavelength conversion member in which an inorganic phosphor powder is dispersed in a glass matrix, and which can obtain high light emission efficiency.

As a result of intensive studies, the present inventors have found that the above problem can be solved by forming a specific layer at the interface between the glass matrix and the inorganic phosphor powder, and propose the present invention.

That is, the wavelength conversion member according to the present invention is provided at the interface between the glass matrix, the inorganic phosphor powder dispersed in the glass matrix, and the inorganic phosphor powder and the glass matrix. And an intermediate layer having a thickness of 0.01 to 5 μm made of a reaction product of a glass matrix.

Generally, in a wavelength conversion member in which an inorganic phosphor powder is dispersed in a glass matrix, the refractive index of the inorganic phosphor powder is different from the refractive index of the glass matrix. For example, while the refractive index of borosilicate glass is about 1.5 to 1.6, YAG phosphor powder has a refractive index (about 1.83) higher than that of borosilicate glass by 0.2 or more. Thus, when the refractive index difference between the inorganic phosphor powder and the glass matrix is large, the ratio of the excitation light reflected at the interface between the inorganic phosphor powder and the glass matrix increases. As a result, the excitation light does not efficiently enter the inorganic phosphor powder, and it is difficult to sufficiently increase the conversion efficiency of the excitation light. Therefore, it is difficult to obtain an LED with high luminous efficiency.

In the present invention, an intermediate layer made of a reaction product of both is formed at the interface between the inorganic phosphor powder and the glass matrix in the wavelength conversion member. For this reason, the reflectance in the interface of inorganic fluorescent substance powder and a glass matrix can be reduced. That is, the intermediate layer has an intermediate refractive index between the inorganic phosphor powder and the glass matrix, and the refractive index continuously changes between the glass matrix → the intermediate layer → the inorganic phosphor powder, so that the glass matrix and the inorganic fluorescent material change. The reflection of excitation light at the body powder interface is reduced. Therefore, it becomes possible to improve the luminous efficiency of the LED by using the wavelength conversion member of the present invention. For example, in the case of a wavelength conversion member in which a YAG phosphor is dispersed in borosilicate glass, the refractive index gradually increases from the glass matrix toward the inorganic phosphor powder, so that reflection at the interface hardly occurs.

In addition, even if the thickness of the intermediate layer is too small or too large, no improvement in luminous efficiency is expected. In the present invention, the thickness of the intermediate layer is set to 0.01 μm to 5 μm, thereby realizing high light emission efficiency.

The wavelength conversion member is preferably made of a sintered body of inorganic phosphor powder and glass powder.

According to this configuration, it is possible to easily produce a wavelength conversion member in which inorganic phosphor powder is uniformly dispersed in a glass matrix.

The inorganic phosphor powder is preferably composed of one or more selected from oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides and halophosphates.

The optical device according to the present invention includes the wavelength conversion member according to the present invention.

The manufacturing method of the wavelength conversion member according to the present invention relates to a method for manufacturing the wavelength conversion member according to the present invention. In the method for producing a wavelength conversion member according to the present invention, the mixed powder containing the inorganic phosphor powder and the glass powder is heated at a temperature of 65 ° C. higher than the softening point of the glass powder to 100 ° C. higher than the softening point of the glass powder. Bake in the range.

By firing the mixed powder containing the inorganic phosphor powder and the glass powder at a relatively high temperature of 65 ° C. higher than the softening point of the glass powder to 100 ° C. higher than the softening point of the glass powder, And the glass powder react with each other, and an intermediate layer composed of the inorganic phosphor powder and the glass reaction product can be suitably formed at the interface between the two.

It is a typical expanded sectional view of the wavelength conversion member concerning one embodiment of the present invention. 1 is a schematic side view of an optical device according to an embodiment of the present invention.

As shown in FIG. 1, in the wavelength conversion member 1 of the present embodiment, an intermediate layer 4 made of a reaction product of an inorganic phosphor powder and glass is formed at the interface between the inorganic phosphor powder 2 and the glass matrix 3. It is characterized by that. The thickness of the intermediate layer 4 is 0.01 μm to 5 μm, preferably 0.1 μm to 4 μm. When the thickness of the intermediate layer 4 is less than 0.01 μm, it is difficult to obtain an effect of suppressing reflection of excitation light at the interface between the inorganic phosphor powder 2 and the glass matrix 3. On the other hand, if the thickness of the intermediate layer 4 is greater than 5 μm, the proportion of the inorganic phosphor powder 2 in the wavelength conversion member 1 decreases as the proportion of the intermediate layer 4 in the wavelength conversion member 1 increases. For this reason, the conversion efficiency of the wavelength conversion member 1 may become too low. Therefore, a decrease in light emission intensity of a light emitting device such as an LED using the wavelength conversion member 1 is likely to decrease.

As described later, the thickness of the intermediate layer 4 can be adjusted by controlling the heat treatment temperature when the wavelength conversion member 1 is manufactured.

Examples of the inorganic phosphor powder 2 include those that emit fluorescence having a wavelength longer than the wavelength of the excitation light when ultraviolet or visible excitation light is incident thereon. For example, when an inorganic phosphor powder that emits a complementary color fluorescence with respect to the hue of the excitation light when an excitation light composed of visible light is incident, white light that is a mixed light of the transmitted excitation light and fluorescence is obtained. A white LED device can be easily obtained. In particular, it is preferable to use the inorganic phosphor powder 2 in which the excitation light is a light beam having a central wavelength of 430 nm to 490 nm and the fluorescence is a light beam having a central wavelength of 530 nm to 590 nm because white light can be easily obtained.

Specific examples of the inorganic phosphor powder 2 preferably used include, for example, garnets such as YAG and other oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, The thing which consists of halophosphate chloride etc. is mentioned.

Among the above inorganic phosphor powders, those having an excitation band at a wavelength of 300 nm to 500 nm and an emission peak at a wavelength of 380 nm to 780 nm, particularly blue (wavelength 440 nm to 480 nm), green (wavelength 500 nm to 540 nm), yellow (wavelength 540 nm) To 595 nm) and red (wavelength 600 nm to 700 nm) are preferably used.

Examples of the inorganic phosphor powder that emits blue light when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 nm to 440 nm include Sr ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ , (Sr, Ba) MgAl ₁₀ O ₁₇ : Eu ²⁺ , (Sr, Ba) ₃ MgSi ₂ O ₈ : Eu ^{2+ and the} like.

As inorganic phosphor powders that emit green fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 nm to 440 nm, SrAl ₂ O ₄ : Eu ²⁺ , SrGa ₂ S ₄ : Eu ²⁺ , SrBaSiO ₄ : Eu ²⁺ , CdS : In, CaS: Ce ³⁺ , Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ²⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , SrSiOn: Eu ²⁺ , ZnS: Al ³⁺ , Cu ⁺ , CaS: Sn ²⁺ , CaS: Sn ²⁺ , F, CaSO ₄ : Ce ³⁺ , Mn ²⁺ , LiAlO ₂ : Mn ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ , ZnS: Cu ⁺ , Cl ⁻ , Ca ₃ WO ₆ : U, Ca ₃ SiO ₄ Cl ₂ : Eu ²⁺ , Sr _0.2 Ba _0.7 Cl _1.1 Al ₂ O _3.45 : Ce ^{3 +} , Mn ²⁺ , Ba ₂ MgSi ₂ O ₇ : Eu ²⁺ , Ba ₂ SiO ₄ : Eu ²⁺ , Ba ₂ Li ₂ Si ₂ O ₇ : Eu ²⁺ , ZnO: S, ZnO: Zn, Ca ₂ Ba ₃ (PO ₄ ) ₃ Cl: Eu ²⁺ , BaAl ₂ O ₄ : Eu ^{2+ and the} like.

Inorganic phosphor powders that emit green fluorescence when irradiated with blue excitation light having a wavelength of 440 nm to 480 nm include SrAl ₂ O ₄ : Eu ²⁺ , SrGa ₂ S ₄ : Eu ²⁺ , SrBaSiO ₄ : Eu ²⁺ , CdS: In, CaS: Ce ³⁺ , Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ²⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , SrSiOn: Eu ^{2+ and the} like.

Inorganic phosphor powders that emit yellow fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 nm to 440 nm include ZnS: Eu ²⁺ , Ba ₅ (PO ₄ ) ₃ Cl: U, Sr ₃ WO ₆ : U, CaGa ₂ S ₄ : Eu ²⁺ , SrSO ₄ : Eu ²⁺ , Mn ²⁺ , ZnS: P, ZnS: P ³⁻ , Cl ⁻ , ZnS: Mn ^{2+ and the} like can be mentioned.

Inorganic phosphor powders that emit yellow fluorescence when irradiated with blue excitation light having a wavelength of 440 nm to 480 nm include Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ²⁺ , Ba ₅ (PO ₄ ) ₃ Cl: U, CaGa ₂ S ₄ : Eu ²⁺ , Sr ₂ SiO ₄ : Eu ²⁺ .

Examples of the inorganic phosphor powder that emits red fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 nm to 440 nm include CaS: Yb ²⁺ , Cl, Gd ₃ Ga ₄ O ₁₂ : Cr ³⁺ , CaGa ₂ S ₄ : Mn ²⁺ , Na (Mg, Mn) ₂ LiSi ₄ O ₁₀ F ₂ : Mn, ZnS: Sn ²⁺ , Y ₃ Al ₅ O ₁₂ : Cr ³⁺ , SrB ₈ O ₁₃ : Sm ²⁺ , MgSr ₃ Si ₂ O ₈ : Eu ²⁺ , Mn ²⁺ , α-SrO.3B ₂ O ₃ : Sm ²⁺ , ZnS—CdS, ZnSe: Cu ⁺ , Cl, ZnGa ₂ S ₄ : Mn ²⁺ , ZnO: Bi ³⁺ , BaS: Au, K, ZnS: Pb ²⁺ ZnS: Sn ²⁺ , Li ⁺ , ZnS: Pb, Cu, CaTiO ₃ : Pr ³⁺ , CaTiO ₃ : Eu ³⁺ , Y ₂ O ₃ : Eu ³⁺ , (Y, Gd) ₂ O ₃ : Eu ³⁺ , CaS: Pb ²⁺ , Mn ²⁺ , YPO ₄ : Eu ³⁺ , Ca ₂ MgSi ₂ O ₇ : Eu ²⁺ , Mn ²⁺ , Y (P, V) O ₄ : Eu ³⁺ , Y ₂ O ₂ S: Eu ³⁺ , SrAl ₄ O ₇ : Eu ³⁺ , CaYAlO ₄ : Eu ³⁺ , LaO ₂ S: Eu ³⁺ , LiW ₂ O ₈ : Eu ³⁺ , Sm ³⁺ , (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , Mn ²⁺ , Ba ₃ MgSi ₂ O ₈ : Eu ²⁺ , Mn ^{2+ and the} like.

As inorganic phosphor powders that emit red fluorescence when irradiated with blue excitation light having a wavelength of 440 nm to 480 nm, ZnS: Mn ²⁺ , Te ²⁺ , Mg ₂ TiO ₄ : Mn ⁴⁺ , K ₂ SiF ₆ : Mn ⁴⁺ , SrS: Eu ²⁺ , CaS: Eu ²⁺ , Na _1.23 K _0.42 Eu _0.12 TiSi ₄ O ₁₁ , Na _1.23 K _0.42 Eu _0.12 TiSi ₅ O ₁₃ : Eu ³⁺ , CdS: In, Te CaAlSiN ₃ : Eu ²⁺ , CaSiN ₃ : Eu ²⁺ , (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ , Eu ₂ W ₂ O _{7 and the} like.

A plurality of inorganic phosphor powders may be mixed and used in accordance with the wavelength range of excitation light or light emission. For example, when white light is obtained by irradiation with ultraviolet excitation light, inorganic phosphor powders emitting blue, green, yellow, and red fluorescence may be mixed and used.

The glass matrix 3 has a role as a medium for stably holding the inorganic phosphor powder 2. In addition, since the color tone of the wavelength conversion member 1 varies depending on the glass composition of the glass matrix 3 and the reactivity with the inorganic phosphor powder 2 varies, the glass composition of the glass matrix 3 to be used is determined in consideration of these conditions. It is preferable to select. Furthermore, it is also important to determine the addition amount of the inorganic phosphor powder 2 suitable for the glass composition of the glass matrix 3 and the thickness of the wavelength conversion member.

Examples of the glass matrix 3 include SiO ₂ —B ₂ O ₃ —RO-based glass (R represents Mg, Ca, Sr, Ba), SiO ₂ —B ₂ O ₃ —R ′ ₂ O-based glass (R ′ Represents Li, Na, K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —ZnO glass, ZnO—B ₂ O ₃ glass, SnO—P ₂ O ₅ -based glass can be used. What is necessary is just to select these glasses suitably according to the characteristic made into the objective. For example, when firing at a low temperature, ZnO—B ₂ O ₃ based glass or SnO—P ₂ O ₅ based glass having a relatively low softening point may be selected, and when it is desired to improve the weather resistance of the wavelength conversion member 1 SiO ₂ —B ₂ O ₃ —RO glass, SiO ₂ —B ₂ O ₃ —R ′ ₂ O glass, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ -ZnO-based glass may be selected.

When using a _SiO 2 _-B 2 _O 3 -RO based glass as a glass, in _{mol%, SiO 2 30 ~ 80%} , B 2 O 3 1 ~ 30%, MgO 0 ~ 10%, CaO 0 ~ 30%, SrO It is preferable to use a glass containing 0-20%, BaO 0-40%, MgO + CaO + SrO + BaO 5-45%, Al ₂ O ₃ 0-10% and ZnO 0-10%.

In addition to the above components, the total amount of Li ₂ O, Na ₂ O and K ₂ O is 5% in order to improve the meltability of the glass or to lower the softening point of the glass to facilitate firing at a low temperature. Can be added. In addition, up to 5% of P ₂ O _{5 in} order to improve the meltability of the glass, and Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ in order to improve the chemical durability of the glass. , La ₂ O ₃ may be added up to 15% each.

When SiO ₂ —B ₂ O ₃ —R ′ ₂ O-based glass is used as the glass, it is mol%, SiO ₂ 30 to 80%, B ₂ O ₃ 1 to 55%, Li ₂ O 0 to 20%, Na ₂ It is preferable to use a glass containing O 0-25%, K ₂ O 0-25%, Li ₂ O + Na ₂ O + K ₂ O 5-35%, Al ₂ O ₃ 0-10% and ZnO 0-10%. .

In addition to the above components, MgO, CaO, SrO and BaO can be added up to 5% in total in order to improve the meltability of the glass. In addition, in order to improve the melting property of glass, P ₂ O ₅ is up to 5%, and in order to improve the chemical durability of glass, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ and La ₂ O ₃ may be added up to 15% each.

When SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass is used as the glass, it is 30% to 70% SiO ₂ , 15 to 55% B ₂ O _3, 15 to 55% Al ₂ O _{3, and} 15% Li. _{2 O 0 ~ 10%, Na} 2 O 0 ~ 10%, K 2 O 0 ~ 10%, MgO 0 ~ 10%, CaO 0 ~ 10%, SrO 0 ~ 10% , and glasses containing BaO 0 ~ 10% Is preferably used.

In addition to the above components, P ₂ O ₅ can be up to 5% in order to improve the meltability of the glass, and Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , in order to improve the chemical durability of the glass, Gd ₂ O ₃ and La ₂ O ₃ may be added up to 15% each.

When SiO ₂ —B ₂ O ₃ —ZnO-based glass is used as the glass, it is SiO ₂ 5-50%, B ₂ O ₃ 15-55%, ZnO 30-80%, Li ₂ O 0-10% in mol%. It is preferable to use glass containing Na ₂ O 0-10%, K ₂ O 0-10%, MgO 0-10%, CaO 0-10%, SrO 0-10% and BaO 0-10%. .

In addition to the above components, Al ₂ O ₃ may be added up to 5% in order to improve the chemical durability of the glass, and Ta ₂ O ₅ and TiO _{2 in} order to improve the chemical durability of the glass. Nb ₂ O ₅ , Gd ₂ O ₃ , La ₂ O ₃ may be added up to 15% each.

When ZnO—B ₂ O ₃ glass is used as the glass, it is ZnO 30-80%, B ₂ O ₃ 20-70%, SiO ₂ 0-5%, Li ₂ O 0-10%, Na _{2 in} mol%. It is preferable to use a glass containing O 0-10%, K ₂ O 0-10%, MgO 0-10%, CaO 0-10%, SrO 0-10% and BaO 0-10%.

In addition to the above components, Al ₂ O ₃ may be added up to 5% in order to improve the chemical durability of the glass, and Ta ₂ O ₅ and TiO _{2 in} order to improve the chemical durability of the glass. Nb ₂ O ₅ , Gd ₂ O ₃ , La ₂ O ₃ may be added up to 15% each.

When SnO—P ₂ O ₅ glass is used as the glass, it is SnO 35 to 80%, P ₂ O ₅ 5 to 40%, B ₂ O ₃ 0 to 30%, Al ₂ O ₃ 0 to 10% in mol%. SiO ₂ 0-10%, Li ₂ O 0-10%, Na ₂ O 0-10%, K ₂ O 0-10%, MgO 0-10%, CaO 0-10%, SrO 0-10% and Preference is given to using glass containing 0-10% of BaO.

In addition to the above components, ZnO, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , and La ₂ O ₃ may be added up to a total amount of 10% in order to improve the weather resistance. .

In order to lower the softening point and stabilize the glass, it is preferable to set SnO / P ₂ O ₅ (molar ratio) in the range of 0.9 to 16. When SnO / P ₂ O ₅ is smaller than 0.9, the softening point is increased, making low-temperature firing difficult, and the inorganic phosphor powder tends to deteriorate. Further, the weather resistance tends to be remarkably lowered. On the other hand, when SnO / P ₂ O ₅ is larger than 16, devitrification bumps due to Sn are precipitated in the glass, and the transmittance of the glass tends to be lowered. As a result, the wavelength conversion member having high luminous efficiency. 1 is difficult to obtain. A more preferable range of SnO / P ₂ O ₅ is 1.5 to 10, and a more preferable range of SnO / P ₂ O ₅ is 2 to 5.

The wavelength conversion member 1 of the present embodiment is preferably made of a sintered body of a mixed powder containing an inorganic phosphor powder and a glass powder. This is because the inorganic phosphor powder can be easily and uniformly dispersed in the glass matrix.

The average particle diameter D ₅₀ of the glass powder is preferably 0.1 μm to 100 μm, and more preferably 1 μm to 50 μm. When the average particle diameter D ₅₀ of the glass powder is too small, there are cases where the bubble generation amount is too large at the time of firing. If many bubbles are included in the wavelength conversion member 1, it causes light scattering and the light emission efficiency tends to decrease. A preferable porosity is 2% or less, and a more preferable porosity is 1% or less. On the other hand, when the average particle diameter D ₅₀ is too large, the inorganic phosphor powder 2 is less likely to be uniformly dispersed in the wavelength conversion member 1, as a result, there is a tendency that emission efficiency of the wavelength conversion member 1 is reduced.

The light emission efficiency (lm / W) of the wavelength conversion member 1 varies depending on the type and content of the inorganic phosphor powder 2 dispersed in the glass matrix 3 and the thickness of the light emission color conversion member 1. If you want to increase the luminous efficiency of the wavelength conversion member 1, reduce the thickness to increase the transmittance of excitation light or fluorescence, or increase the content of the inorganic phosphor powder 2 to increase the amount of light to be converted. Good. However, if the content of the inorganic phosphor powder 2 is too large, a dense structure is difficult to obtain and the porosity tends to increase. As a result, problems such as difficulty in efficiently irradiating the excitation light to the inorganic phosphor powder, and the mechanical strength of the wavelength conversion member 1 tend to decrease may occur. On the other hand, when there is too little content of the inorganic fluorescent substance powder 2, it becomes difficult to obtain sufficient light emission. Therefore, the content of the inorganic phosphor powder 2 in the wavelength conversion member 1 is preferably from 0.01 to 30%, more preferably from 0.05 to 20%, and more preferably from 0.08 to 0.08% by mass. More preferably, it is 15%.

The wavelength conversion member 1 can be manufactured, for example, by preforming a mixed powder containing an inorganic phosphor powder and a glass powder and firing it at a predetermined temperature. After obtaining the sintered body, if necessary, it may be processed into a desired shape by grinding, polishing, repressing or the like.

The preforming method is not particularly limited, and methods such as a press molding method, an injection molding method, a sheet molding method, and an extrusion molding method can be employed.

The temperature at which the mixed powder of the glass powder and the inorganic phosphor powder is fired is preferably within a temperature range of 65 ° C. higher than the softening point of the glass powder to 100 ° C. higher than the softening point of the glass powder, More preferably, the temperature is within a temperature range from 70 ° C. higher than the softening point of the glass powder to 90 ° C. higher than the softening point of the glass powder. If the firing temperature is lower than a temperature 65 ° C higher than the softening point of the glass powder, the thickness of the intermediate layer between the inorganic phosphor powder and the glass becomes too thin, and reflection at the interface cannot be reduced, resulting in luminous efficiency. Tends to decrease. On the other hand, when the firing temperature is higher than a temperature 100 ° C. higher than the softening point of the glass powder, the reaction between the glass and the inorganic phosphor powder proceeds excessively, and the content of the inorganic phosphor powder is lowered, so the conversion efficiency is low. As a result, the emission intensity tends to decrease.

It is also possible to pulverize the mixed powder of the inorganic phosphor powder and the glass powder to form a reaction product layer (intermediate layer) with glass on the surface of the inorganic phosphor powder by a mechanochemical effect.

As shown in FIG. 2, the wavelength conversion member 1 is used as an optical device 6 such as a white LED combined with a light source 5 such as an LED chip. In this case, the wavelength conversion member 1 may be directly adhered on the light source 5 or may be adhered on a box surrounding the light source 5. Further, by installing a plurality of LED chips below the wavelength conversion member of the plate-like body, it can be used as a surface emitting device having a light emitting function and a diffusing function.

(Example)
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

Table 1 shows examples (No. 2, 5, 8) and comparative examples (No. 1, 3, 4, 6, 7, 9) of the present invention.

First, glass raw materials were weighed and mixed so as to have the glass composition shown in Table 1, and the mixture was melted in a platinum crucible at 900 to 1400 ° C. for 1 hour to be vitrified. Molding the molten glass into a film, and the obtained film-like glass was pulverized by a ball mill and then classified through a sieve of 325 mesh, average particle diameter D ₅₀ was obtained glass powder 30 [mu] m. The softening point of the obtained glass powder was measured. The softening point was measured using a macro type parallax thermal analyzer, and the value of the fourth inflection point of the obtained graph was used as the softening point. The average particle diameter D ₅₀ was dispersed glass powder in water was measured using a laser scattering particle size distribution analyzer.

Next, glass powder and inorganic phosphor powder were mixed so as to have a blending ratio shown in Table 1, and pressure-molded using a mold to prepare a cylindrical preform having a diameter of 1 cm. This preform was fired at the firing temperature shown in Table 1 to obtain a sintered body. The sintered body was polished and processed into a disk shape having a diameter of 8 mm and a thickness of 0.3 mm. About the obtained wavelength conversion member, the thickness and luminous efficiency of the intermediate | middle layer formed in the interface of a glass matrix and inorganic fluorescent substance powder were measured. The results are shown in Table 1. Sample No. In 1, 4, and 7, no intermediate layer was confirmed.

The thickness of the reaction product layer was measured by SEM-EPMA. In addition, by the said measurement, the element contained in inorganic fluorescent substance powder and glass powder was detected in the intermediate | middle layer. As a result, it was confirmed that the intermediate layer was composed of reactive organisms of inorganic phosphor powder and glass powder.

The light emission characteristics of the wavelength conversion member were evaluated as follows. Each sample was excited by a blue LED, and light emitted from the front of the sample was measured in an integrating sphere to obtain its emission spectrum. Luminous efficiency was calculated from the obtained spectrum.

As is clear from Table 1, sample No. which is an example of the present invention. The wavelength conversion members 2, 5, and 8 have a reaction layer thickness in the range of 0.01 to 5 μm. Luminous efficiency was better than that.

Claims (5)

A glass matrix;
An inorganic phosphor powder dispersed in the glass matrix;
A wavelength conversion member provided at an interface between the inorganic phosphor powder and the glass matrix, and comprising an intermediate layer having a thickness of 0.01 μm to 5 μm made of a reaction product of the inorganic phosphor powder and the glass matrix. The wavelength conversion member according to claim 1, comprising a sintered body of the inorganic phosphor powder and glass powder. 2. The inorganic phosphor powder comprising at least one selected from oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, and halophosphate chlorides. 2. The wavelength conversion member according to 2. An optical device comprising the wavelength conversion member according to any one of claims 1 to 3. The method for producing the wavelength conversion member according to any one of claims 1 to 3, wherein the mixed powder containing the inorganic phosphor powder and the glass powder is at a temperature 65 ° C higher than the softening point of the glass powder. A method for producing a wavelength conversion member that is fired in a temperature range of 100 ° C. higher than the softening point of the glass powder.

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