JP6861952B2 - Wavelength conversion member and light emitting device using it - Google Patents

Description

The present invention relates to a wavelength conversion member for converting the wavelength of light emitted by a light emitting element such as a light emitting diode (LED: Light Emitting Diode) or a laser diode (LD: Laser Diode) into another wavelength.

In recent years, as a next-generation light source that replaces fluorescent lamps and incandescent lamps, attention has been increasing to light sources using LEDs and LDs from the viewpoints of low power consumption, small size and light weight, and easy light intensity adjustment. As an example of such a next-generation light source, for example, in Patent Document 1, a light source in which a wavelength conversion member that absorbs a part of the light from the LED and converts it into yellow light is arranged on an LED that emits blue light. Is disclosed. This light source emits white light, which is a composite light of blue light emitted from an LED and yellow light emitted from a wavelength conversion member.

Conventionally, as the wavelength conversion member, a member in which an inorganic phosphor is dispersed in a resin matrix has been used. However, when the wavelength conversion member is used, there is a problem that the resin is deteriorated by the light from the LED and the brightness of the light source tends to be lowered. In particular, there is a problem that the resin matrix is deteriorated by the heat generated by the LED or high-energy short-wavelength (blue to ultraviolet) light, causing discoloration or deformation.

Therefore, a wavelength conversion member made of a completely inorganic solid in which an inorganic phosphor is dispersed and fixed in a glass matrix instead of a resin has been proposed (see, for example, Patent Documents 2 and 3). The wavelength conversion member has a feature that the glass as a base material is less likely to be deteriorated by the heat of the LED chip or the irradiation light, and problems such as discoloration and deformation are less likely to occur.

However, the wavelength conversion members described in Patent Documents 2 and 3 have a problem that the inorganic phosphor is deteriorated by firing at the time of manufacture and the brightness is easily deteriorated. In particular, in applications such as general lighting and special lighting, high color rendering properties are required, so it is necessary to use an inorganic phosphor having relatively low heat resistance such as red or green, and the deterioration of the inorganic phosphor becomes remarkable. Tend. Therefore, a wavelength conversion member in which the softening point of the glass powder is lowered by containing an alkali metal oxide in the glass composition has been proposed (see, for example, Patent Document 4). Since the wavelength conversion member can be manufactured by firing at a relatively low temperature, deterioration of the inorganic phosphor during firing can be suppressed.

Japanese Unexamined Patent Publication No. 2000-208815 Japanese Unexamined Patent Publication No. 2003-258308 Japanese Patent No. 4895541 JP-A-2007-302858

The wavelength conversion member described in Patent Document 4 has a problem that the emission intensity tends to decrease with time. With the further increase in the output of light sources such as LEDs and LDs in recent years, the decrease in emission intensity with time has become more and more remarkable.

Therefore, an object of the present invention is to provide a wavelength conversion member having a small decrease in emission intensity with time when irradiated with light from an LED or LD, and a light emitting device using the same.

In the wavelength conversion member of the present invention, the inorganic phosphor is dispersed in the glass matrix, and the glass matrix is in mol%, SiO ₂ 40 to 60%, B ₂ O ₃ 0.1 to 35%, Al ₂ O. ₃ 0.1 to 10%, Li ₂ O 0 to 10%, Na ₂ O 0 to 10%, K ₂ O 0 to 10%, Li ₂ O + Na ₂ O + K ₂ O 0.1 to 10%, MgO 0 to 45 %, CaO 0-45%, SrO 0-45%, BaO 0-45%, MgO + CaO + SrO + BaO 0.1-45%, and ZnO 0-15%. At least one selected from the group consisting of phosphors, oxynitride phosphors, chloride phosphors, acidified phosphors, halide phosphors, aluminate phosphors and halophosphate phosphors. It is characterized by.

The present inventors have found that the decrease in emission intensity of the wavelength conversion member with time is particularly affected _{by the alkali metal component and the SiO 2 component contained in the glass composition.} The mechanism is inferred as follows.

When the glass matrix containing an alkali metal element in the composition is irradiated with excitation light, the electrons existing in the outermost shell of oxygen ions in the glass matrix are excited by the energy of the excitation light and separated from the oxygen ions. A part of it combines with alkaline ions in the glass matrix to form a colored center (where vacancies are formed after the alkaline ions are removed). On the other hand, the holes generated by the escape of electrons move in the glass matrix, and some of them are captured by the holes formed after the alkali ions are removed to form a colored center. It is considered that these colored centers formed in the glass matrix serve as an absorption source of excitation light and fluorescence, and the emission intensity of the wavelength conversion member decreases. Further, the heat generated from the inorganic phosphor (heat generated due to the wavelength conversion loss) tends to activate the movement of electrons, holes, and alkaline ions in the glass matrix. As a result, the formation of the coloring center is accelerated, and the emission intensity tends to decrease. Therefore, in the present invention, while containing the alkali metal element as an essential component, the content thereof is regulated to be small as described above, thereby suppressing the increase in the softening point and suppressing the generation of the coloring center.

Further, when the SiO ₂ content is high in the composition, the proportion of Si—O—Si bonds, which are network formers, increases in the glass matrix, and the glass matrix structure is stabilized. Therefore, the non-crosslinked oxygen formed by breaking the bond between Si and O in the Si—O—Si bond is stably retained, and the non-crosslinked oxygen becomes a coloring center and causes a decrease in emission intensity. Become. On the other hand, when the SiO ₂ content is low in the composition, the content of other components is relatively high, and bonds other than the Si—O—Si bond increase (for example, Ba or Na between Si and O). The stability of the glass matrix structure is reduced due to the entry of other elements such as. When non-crosslinked oxygen is formed in that state, the stability of the bonded state around the Si element is reduced, so that the non-crosslinked oxygen is less likely to be stably retained. As a result, the formation of coloring centers is suppressed.

The glass matrix in the wavelength conversion member of the present invention contains an alkaline earth oxide (including MgO) as an essential component. Alkali earth oxides inhibit the movement of alkali metal ions and other ions in the glass matrix. As a result, it becomes difficult to form a colored center, and it is possible to suppress a decrease in emission intensity with time.

In the wavelength conversion member of the present invention, it is preferable that the glass matrix contains 0.1% or more of _{Li 2} O, Na ₂ O and K _{2 O, respectively.}

In the wavelength conversion member of the present invention, the softening point of the glass matrix is preferably 400 to 800 ° C.

The wavelength conversion member of the present invention preferably contains an inorganic phosphor in an amount of 0.01 to 30% by mass.

The wavelength conversion member of the present invention is preferably made of a powder sintered body.

The light emitting device of the present invention is characterized by comprising the above-mentioned wavelength conversion member and a light source for irradiating the wavelength conversion member with excitation light.

According to the present invention, it is possible to provide a wavelength conversion member having a small decrease in emission intensity with time when irradiated with light from an LED or LD, and a light emitting device using the same.

It is a schematic side view of the light emitting device which concerns on one Embodiment of this invention.

The wavelength conversion member of the present invention is formed by dispersing an inorganic phosphor in a glass matrix. Glass matrix, in _{mol%, SiO 2 40~60%, B} 2 O 3 0.1~35%, Al 2 O 3 0.1~10%, Li 2 O 0~10%, Na 2 O 0~ 10%, K ₂ O 0-10%, Li ₂ O + Na ₂ O + K ₂ O 0.1-10%, MgO 0-45%, CaO 0-45%, SrO 0-45%, BaO 0-45%, MgO + CaO + SrO + BaO It contains 0.1 to 45% and ZnO 0 to 15%. The reason for limiting the glass composition range in this way will be described below.

SiO ₂ is a component that forms a glass network. The content of SiO ₂ is 40 to 60%, preferably 45 to 55%. If _{the content of SiO 2} is too small, the weather resistance and mechanical strength tend to decrease. On the other hand, _{if the content of SiO 2} is too large, the emission intensity tends to decrease with time. In addition, the sintering temperature becomes high during the manufacture of the wavelength conversion member, and the inorganic phosphor tends to deteriorate.

B ₂ O ₃ is a component that lowers the melting temperature and significantly improves the meltability. The content of B ₂ O ₃ is 0.1 to 35%, preferably 1 to 30%. If _{the content of B 2} O ₃ is too small, it becomes difficult to obtain the above effect. In addition, the sintering temperature becomes high during the manufacture of the wavelength conversion member, and the inorganic phosphor tends to deteriorate. On the other hand, _{if the content of B 2} O ₃ is too large, the emission intensity tends to decrease with time. In addition, the weather resistance tends to decrease.

The ratio of SiO ₂ and B ₂ O _{3 SiO 2} / B ₂ O ₃ (molar ratio) is 1 to 7, 1 to 6.5, 1.1 to 6, 1.15 to 5, 1.2. It is preferably ~ 4, 1.5 to 3.5, particularly 1.7 to 2.5. If the value of _{SiO 2} / B ₂ O _{3 is too large, the proportion of SiO 2} becomes large, a colored center due to desorption of the O element is likely to be formed, and the emission intensity tends to decrease with time. On the other hand, if the value of _{SiO 2} / B ₂ O _{3 is too small, the ratio of B 2} O ₃ becomes large, and the weather resistance tends to decrease.

Al ₂ O ₃ is a component that improves weather resistance and mechanical strength. The content of Al ₂ O ₃ is 0.1 to 10%, preferably 2 to 8%. If _{the content of Al 2} O ₃ is too small, it becomes difficult to obtain the above effect. On the other hand, _{if the content of Al 2} O ₃ is too large, the meltability tends to decrease.

In order to achieve high weather resistance, _{the content of SiO 2} + B ₂ O ₃ + Al ₂ O ₃ is preferably 55% or more, more preferably 60% or more, and 65% or more. More preferably, it is particularly preferably 67% or more, and most preferably 70% or more. The upper limit of the content of SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ is not particularly limited, but if it is too large, the meltability tends to decrease, so it is preferably 85% or less, and more preferably 84% or less. It is preferably 83% or less, and more preferably 83% or less.

Li ₂ O, Na ₂ O and K ₂ O are components that lower the melting temperature to improve the meltability and lower the softening point. The contents of these components are 0 to 10%, preferably 0 to 5%, and more preferably 0.1 to 2%, respectively. If the content of these components is too high, the weather resistance tends to decrease.

The content of Li ₂ O + Na ₂ O + K ₂ O is 0.1 to 10%, preferably 1 to 7%, and more preferably 2 to 5%. If _{the content of Li 2} O + Na ₂ O + K ₂ O is too small, the softening point is unlikely to decrease. On the other hand, _{if the content of Li 2} O + Na ₂ O + K ₂ O is too large, the weather resistance tends to decrease, and the light emission intensity tends to decrease with time due to the light irradiation of the LED or LD. Li ₂ O, Na ₂ O and K ₂ O are preferably used in combination of two or more, particularly three. Specifically, _{it is preferable to contain Li 2} O, Na ₂ O and K ₂ O in an amount of 0.1% or more, respectively. In this way, the softening point can be efficiently lowered due to the mixed alkali effect. Further, when the contents of each alkali oxide are the same, the mixed alkali effect can be easily obtained.

In order to achieve high weather resistance, the _{total amount of SiO 2} , B ₂ O ₃ and Al ₂ O ₃ , which are components that contribute to the improvement of weather resistance, and the alkali metal oxide (Li ₂ O,) that causes a decrease in weather resistance. It is preferable to appropriately adjust the ratio of the contents of Na ₂ O and K _{2 O).} Specifically, (Li ₂ O + Na ₂ O + K ₂ O) / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) (molar ratio) is preferably 0.2 or less, and preferably 0.18 or less. More preferably, it is 0.15 or less.

MgO, CaO, SrO and BaO are components that lower the melting temperature to improve the meltability and lower the softening point. In addition, since it inhibits the movement of ions that cause the formation of colored centers due to light irradiation of LEDs and LDs, it also has the effect of suppressing a decrease in emission intensity over time. The content of each of these components is 0 to 45%, preferably 10 to 45%, particularly preferably 15 to 35%. If the content of these components is too high, the weather resistance tends to decrease. In addition, BaO having a large mass number has a large effect of inhibiting the movement of ions that cause the formation of colored centers, and can effectively suppress a decrease in emission intensity with time.

The content of MgO + CaO + SrO + BaO is 0.1 to 45%, preferably 0.1 to 40%, more preferably 0.1 to 35%, and further preferably 1 to 30%. It is preferably 5 to 25%, and particularly preferably 5 to 25%. If the content of MgO + CaO + SrO + BaO is too small, it becomes difficult to reduce the softening point, and it becomes difficult to obtain the effect of suppressing the decrease in emission intensity over time. On the other hand, if the content of MgO + CaO + SrO + BaO is too large, the weather resistance tends to decrease.

ZnO is a component that lowers the melting temperature and improves the meltability. The ZnO content is 0 to 15%, preferably 0 to 12%, more preferably 0 to 10%, and even more preferably 1 to 7%. If the ZnO content is too high, the weather resistance tends to decrease.

In addition to the above components, various components can be contained as long as the effects of the present invention are not impaired. For example, P ₂ O ₅ , La ₂ O ₃ , Ta ₂ O ₅ , TeO ₂ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , Y ₂ O ₃ , CeO ₂ , Sb ₂ O ₃ , SnO ₂ , Bi. ₂ O ₃ and ZrO _{2 and the} like may be contained in a range of 15% or less, further 10% or less, particularly 5% or less, and a total amount of 30% or less. It can also contain F. Since F has the effect of reducing the softening point, by containing it instead of the alkali metal component, which is one of the causes of the formation of the coloring center, the softening point is maintained and the decrease in emission intensity with time is suppressed. be able to. The content of F is preferably 0 to 20%, 0 to 10%, particularly 0.1 to 5% in terms of anion%.

The softening point of the glass matrix is preferably 400 to 800 ° C., more preferably 450 to 750 ° C., and even more preferably 500 to 700 ° C. If the softening point is too low, the mechanical strength and weather resistance are likely to decrease. On the other hand, if the softening point is too high, the inorganic phosphor tends to deteriorate due to firing during production.

In general, inorganic phosphors often have a higher refractive index than glass. In the wavelength conversion member, if the difference in refractive index between the inorganic phosphor and the glass matrix is large, the excitation light is likely to be scattered at the interface between the inorganic phosphor and the glass matrix. As a result, the irradiation efficiency of the excitation light on the inorganic phosphor becomes high, and the luminous efficiency tends to improve. However, if the difference in refractive index between the inorganic phosphor and the glass matrix is too large, the excitation light is scattered excessively, resulting in scattering loss and conversely, the luminous efficiency tends to decrease. In view of the above, the difference in refractive index between the inorganic phosphor and the glass matrix is preferably about 0.001 to 0.5. The refractive index (nd) of the glass matrix is preferably 1.45 to 1.8, more preferably 1.47 to 1.75, and further preferably 1.48 to 1.6. preferable.

The inorganic phosphor in the present invention includes an oxide phosphor (including a garnet-based phosphor such as a YAG phosphor), a nitride phosphor, an oxynitride phosphor, a chloride phosphor, a acidified phosphor, and a halide. It is at least one selected from the group consisting of a fluorescent substance, an aluminate fluorescent substance and a halophosphate-ized fluorescent substance. Of these inorganic phosphors, oxide phosphors, nitride phosphors and oxynitride phosphors are preferable because they have high heat resistance and are relatively resistant to deterioration during firing. The nitride phosphor and the oxynitride phosphor have a feature that the excitation light of near-ultraviolet to blue is converted into a wide wavelength region of green to red, and the emission intensity is relatively high. Therefore, the nitride phosphor and the oxynitride phosphor are particularly effective as the inorganic phosphor used in the wavelength conversion member for the white LED element. In order to suppress the heat generated from the inorganic phosphor from being conducted to the glass matrix, a coated inorganic phosphor may be used. As a result, the activation of the movement of electrons, holes, and alkaline ions in the glass matrix can be suppressed, and as a result, the formation of colored centers can be suppressed. Oxides are preferable as the coating material. Examples of phosphors other than the above include sulfide phosphors, but the sulfide phosphors are not used in the present invention because they tend to deteriorate over time or react with the glass matrix to reduce the emission intensity. ..

Examples of the inorganic phosphor have an excitation band at a wavelength of 300 to 500 nm and an emission peak at a wavelength of 380 to 780 nm, particularly blue (wavelength 440 to 480 nm), green (wavelength 500 to 540 nm), and yellow (wavelength 540 to 540 nm). Those that emit light in red (wavelength 600 to 700 nm) can be mentioned.

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

Inorganic phosphors that emit green fluorescence when irradiated with excitation light with a wavelength of 300 to 440 nm from ultraviolet to near ultraviolet are SrAl ₂ O ₄ : Eu ²⁺ , SrBaSiO ₄ : Eu ²⁺ , Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ³⁺ , SrSiON: Eu ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , 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⁺ BaAl ₂ O ₄ : Eu ^{2+ and the} like can be mentioned.

Examples of inorganic phosphors that emit green fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm include SrAl ₂ O ₄ : Eu ²⁺ , SrBaSiO ₄ : Eu ²⁺ , and Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ^3+. , SrSiON: Eu ²⁺ , β-SiAlON: Eu ^{2+ and the} like.

Examples of the inorganic phosphor that emits yellow fluorescence when irradiated with ultraviolet-near-ultraviolet excitation light having a wavelength of 300 to 440 nm include La ₃ Si ₆ N ₁₁ : Ce ^{3+ and the} like.

Examples of the inorganic phosphor that emits yellow fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm include Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ³⁺ and Sr ₂ SiO ₄ : Eu ²⁺ .

As inorganic phosphors that emit red fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light with a wavelength of 300 to 440 nm, MgSr ₃ Si ₂ O ₈ : Eu ²⁺ , Mn ²⁺ , Ca ₂ MgSi ₂ O ₇ : Eu ²⁺ , Mn ^{2+ and the} like can be mentioned.

Examples of inorganic phosphors that emit red fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm include CaAlSiN ₃ : Eu ²⁺ , CaSiN ₃ : Eu ²⁺ , (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ , α. −SiAlON: Eu ^{2+ and the} like.

In addition, a plurality of inorganic phosphors may be mixed and used according to the wavelength range of excitation light or emission. For example, when white light is obtained by irradiating excitation light in the ultraviolet region, an inorganic phosphor that emits blue, green, yellow, and red fluorescence may be mixed and used.

The luminous efficiency (lm / W) of the wavelength conversion member changes depending on the type and content of the inorganic phosphor, the thickness of the wavelength conversion member, and the like. The content of the inorganic phosphor and the thickness of the wavelength conversion member may be appropriately adjusted so as to optimize the luminous efficiency. If the content of the inorganic phosphor is too high, it becomes difficult to sinter, the porosity becomes large, it becomes difficult for the excitation light to be efficiently irradiated to the inorganic phosphor, and the mechanical strength of the wavelength conversion member decreases. There is a risk of problems such as On the other hand, if the content of the inorganic phosphor is too small, it becomes difficult to obtain a desired emission intensity. From such a viewpoint, the content of the inorganic phosphor in the wavelength conversion member of the present invention is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and 0. It is more preferably 08 to 20% by mass.

In addition, in the wavelength conversion member whose purpose is to reflect the fluorescence generated in the wavelength conversion member to the side where the excitation light is incident and mainly extract only the fluorescence to the outside, the emission intensity is maximized, not limited to the above. As described above, the content of the inorganic phosphor can be increased (for example, 30 to 80% by mass, and further 40 to 75% by mass).

In addition to the inorganic phosphor, the wavelength conversion member of the present invention may contain a total amount of a light diffusing material such as alumina, silica, and magnesia up to 30% by mass.

The wavelength conversion member of the present invention is preferably made of a powder sintered body. Specifically, it is preferably composed of a sintered body of a mixed powder containing a glass powder and an inorganic fluorescent substance powder. In this way, it is possible to easily manufacture a wavelength conversion member in which the inorganic phosphor is uniformly dispersed in the glass matrix.

The maximum particle size D _max of the glass powder is preferably 200 μm or less, more preferably 150 μm or less, and further preferably 105 μm or less. The average particle size D ₅₀ of the glass powder is preferably 0.1 μm or more, more preferably 1 μm or more, and further preferably 2 μm or more. If the maximum particle size D _max of the glass powder is too large, the excitation light is less likely to be scattered in the obtained wavelength conversion member, and the luminous efficiency is likely to decrease. Further, if the average particle size D ₅₀ of the glass powder is too small, the excitation light is excessively scattered in the obtained wavelength conversion member, and the luminous efficiency tends to decrease.

In the present invention, the maximum particle size D _max and the average particle size D ₅₀ refer to the values measured by the laser diffraction method.

The firing temperature of the mixed powder containing the glass powder and the inorganic phosphor is preferably within ± 150 ° C., and more preferably within ± 100 ° C., the softening point of the glass powder. If the firing temperature is too low, the glass powder does not flow and it is difficult to obtain a dense sintered body. On the other hand, if the firing temperature is too high, the inorganic phosphor component may be eluted into the glass to reduce the emission intensity, or the inorganic phosphor component may diffuse into the glass to color the glass and reduce the emission intensity. is there.

Further, it is preferable that the firing is performed in a reduced pressure atmosphere. Specifically, it is preferable that the atmosphere during firing is less than 1.013 × ¹⁰ 5 Pa, more preferably at most 1000 Pa, and more preferably less 400 Pa. Thereby, the amount of bubbles remaining in the wavelength conversion member can be reduced. As a result, the scattering factor in the wavelength conversion member can be reduced, and the luminous efficiency can be improved. The entire firing step may be performed in a reduced pressure atmosphere. For example, only the firing step is performed in a reduced pressure atmosphere, and the temperature raising and lowering steps before and after the firing step are performed in an atmosphere other than the reduced pressure atmosphere (for example, under atmospheric pressure). You may go.

The shape of the wavelength conversion member of the present invention is not particularly limited, and is not limited to a member having a specific shape itself such as a plate shape, a columnar shape, a hemispherical shape, or a hemispherical dome shape, but also a base such as a glass substrate or a ceramic substrate. A film-like sintered body formed on the surface of the material is also included.

FIG. 1 shows an embodiment of the light emitting device of the present invention. As shown in FIG. 1, the light emitting device 1 includes a wavelength conversion member 2 and a light source 3. The light source 3 irradiates the wavelength conversion member 2 with the excitation light L1. The excitation light L1 incident on the wavelength conversion member 2 is converted into fluorescence L2 having a different wavelength, and is emitted from the side opposite to the light source 3. At this time, the combined light of the excitation light L1 transmitted without wavelength conversion and the fluorescence L2 may be emitted.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

(1) Preparation of glass powder Tables 1 and 2 show the glass powders (samples A to M) used in Examples and the glass powders (Samples N to P) used in Comparative Examples.

First, the raw materials were prepared so as to have the glass composition shown in Tables 1 and 2. The raw material was melted and vitrified at a temperature of 800 to 1500 ° C. for 1 to 2 hours using a platinum crucible, and the molten glass was poured between a pair of cooling rollers to form a film. The film-shaped glass molded body was pulverized with a ball mill and then classified to obtain a glass powder having _{an average particle diameter D 50 of 2.5 μm.} The softening point and weather resistance of the obtained glass powder were measured by the following methods.

For the softening point, a fiber erongation method was used, and a temperature at which the ^{viscosity was 107.6 dPa · s was adopted.}

Weather resistance was evaluated as follows. The glass powder was pressure-molded with a mold to prepare a columnar premolded body having a diameter of 1 cm, and the columnar sintered body sample was obtained by firing at the firing temperatures shown in Tables 1 and 2. The weather resistance was evaluated by holding the sample for 300 hours under the conditions of 121 ° C., 95% RH, and 2 atm using a HAST tester PC-242HSR2 manufactured by Hirayama Seisakusho, and observing the sample surface. Specifically, in optical microscope observation (× 500), “○” indicates that the sample surface does not change before and after the test, and “○” indicates that the glass component is precipitated or the gloss is lost on the sample surface. It was evaluated as "x".

(2) Preparation of Wavelength Converting Member Tables 3 to 6 show Examples (Samples 1 to 13, 17 to 29) and Comparative Examples (14 to 16, 30 to 32) of the present invention.

The inorganic fluorescent powders shown in Tables 3 to 6 were mixed with each of the glass powder samples shown in Tables 1 and 2 at a predetermined mass ratio to obtain a mixed powder. The mixed powder was pressure-molded with a mold to prepare a columnar premolded body having a diameter of 1 cm. After firing the preformed body, the obtained sintered body was processed to obtain a disk-shaped wavelength conversion member having a diameter of 8 mm and a thickness of 0.2 mm. As the firing temperature, the firing temperatures shown in Tables 1 and 2 were adopted according to the glass powder used. The emission spectrum of the obtained wavelength conversion member was measured, and the luminous efficiency was calculated. The results are shown in Tables 3-6.

Luminous efficiency was determined as follows. First, a wavelength conversion member was placed on a light source having an excitation wavelength of 460 nm, and the energy distribution spectrum of light emitted from the upper surface of the wavelength conversion member was measured in the integrating sphere. Next, the total luminous flux was calculated by multiplying the obtained spectrum by the standard luminous efficiency, and the total luminous flux was divided by the power of the light source to calculate the luminous efficiency.

Next, the above wavelength conversion member was processed into a 1.2 mm square to obtain a small piece of wavelength conversion member. A small piece of wavelength conversion member was placed on an LED chip having an emission wavelength of 445 nm energized at 650 mA, and continuous light irradiation was performed for 100 hours. For the wavelength conversion member before and after light irradiation for 100 hours, the energy distribution spectrum of the light emitted from the upper surface of the wavelength conversion member in the integrating sphere was measured using a general-purpose emission spectrum measuring device. The total luminous flux value was calculated by multiplying the obtained emission spectrum by the standard luminous efficiency. The rate of change of the total luminous flux value is represented by a value (%) obtained by dividing the total luminous flux value after 100 hours of light irradiation by the total luminous flux value before light irradiation and multiplying by 100, and is shown in Tables 3 to 6.

As is clear from Tables 3 and 4, when α-SiAlON is used as the inorganic phosphor, the wavelength conversion members of Examples 1 to 13 have a total luminous flux value after 100 hours of light irradiation before light irradiation. In contrast to the wavelength conversion member of 14 to 16 which is a comparative example, the total luminous flux value after 100 hours of light irradiation is greatly reduced to 96.5% or less before light irradiation. did.

As is clear from Tables 5 and 6, when YAG was used as the inorganic phosphor, the wavelength conversion members of Examples 17 to 29 were not confirmed to have a decrease in the total luminous flux value even after 100 hours of light irradiation. On the other hand, in the wavelength conversion members of 30 to 32, which are comparative examples, the total luminous flux value after 100 hours of light irradiation was significantly reduced to 98.5% or less before the light irradiation.

The wavelength conversion member of the present invention is suitable as a constituent member for general lighting such as a white LED, special lighting (for example, a projector light source, an automobile headlamp light source), and the like.

1 Light emitting device 2 Wavelength conversion member 3 Light source

Claims (7)

A wavelength conversion member in which an inorganic phosphor is dispersed in a glass matrix.
Said glass matrix, in _{mol%, SiO 2 40~53%, B} 2 O 3 0.1~35%, Al 2 O 3 0.1~10%, Li 2 O 0~10%, Na 2 O 0 10%, K ₂ O 0 _{to 10%, Li 2} O + Na ₂ O + K ₂ O 0.1 to 10% (provided that at least two types selected from _{Li 2} O, Na ₂ O, K _{2 O are included), MgO} It contains 0-45%, CaO 0-45%, SrO 0-45%, BaO 0-45%, MgO + CaO + SrO + BaO 0.1-45%, and ZnO 0-15%.
(Li ₂ O + Na ₂ O + K ₂ O) / (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is 0.04 to 0.0 9 .
A wavelength conversion member characterized in that the inorganic phosphor is α-SiAlON. The wavelength conversion member according to claim 1, wherein the glass matrix _{contains SiO 2} + B ₂ O ₃ + Al ₂ O ₃ 55% or more. The wavelength conversion member according to claim 1 or 2 , wherein the glass matrix contains 0.1% or more of _{Li 2} O, Na ₂ O, and K _{2 O, respectively.} The wavelength conversion member according to any one of claims 1 to 3 , wherein the softening point of the glass matrix is 400 to 800 ° C. The wavelength conversion member according to any one of claims 1 to 4 , wherein the inorganic phosphor is contained in an amount of 0.01 to 30% by mass. The wavelength conversion member according to any one of claims 1 to 5 , wherein the wavelength conversion member is made of a powder sintered body. A light emitting device comprising the wavelength conversion member according to claims 1 to 6 and a light source for irradiating the wavelength conversion member with excitation light.

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