TW201527487A - Wavelength conversion member and light emitting device - Google Patents

Abstract

The present invention provides a wavelength conversion member having a small decrease in luminous intensity with time when a light of an LED or LD is irradiated. The wavelength conversion member of the present invention is characterized by comprising a sintered body comprising (a) a glass powder containing an alkali metal element and a polyvalent element as a glass composition, and (b) a mixed powder of an inorganic phosphor powder.

Description

Wavelength conversion member and light emitting device

The present invention relates to a wavelength conversion member that converts a wavelength of light emitted from a light emitting diode (LED) or a laser diode (LD) to another wavelength.

In recent years, as a next-generation light source that is converted into a fluorescent lamp or an incandescent lamp, attention has been paid to the use of LEDs or LDs in terms of low power consumption, small size and light weight, and easy adjustment of the amount of light. As an example of such a next-generation light source, for example, Patent Document 1 discloses a light source in which a light-emitting member that absorbs a part of light from an LED and converts it into yellow light is disposed on an LED that emits blue light. The light source emits white light from the blue light emitted from the LED and the yellow light emitted from the wavelength conversion member.

As the wavelength converting member, those conventionally used for dispersing inorganic phosphor powder in a resin matrix have been used. However, when the wavelength conversion member is used, there is a problem that the resin is deteriorated due to light from the LED, and the brightness of the light source is easily lowered. In particular, there is a problem that the mold resin is deteriorated due to heat generated by the LED or short-wavelength (blue-ultraviolet) light of high energy, causing discoloration or deformation.

Therefore, a wavelength conversion member in which a completely inorganic solid in which an inorganic phosphor powder is dispersed and fixed in a glass matrix instead of a resin is proposed (see, for example, Patent Documents 2 and 3). This wavelength conversion member is characterized in that it is difficult for the glass to be a base material to be deteriorated by heat of the LED wafer or irradiation light, and it is difficult to cause discoloration or deformation.

However, the above-mentioned wavelength conversion member is likely to cause inorganic firefly due to baking at the time of manufacture. The problem that the light body powder is deteriorated and the brightness is deteriorated. In particular, in general lighting, special lighting, etc., in order to achieve high color rendering properties, it is necessary to use an inorganic phosphor powder having a relatively low heat resistance such as red or green, and the deterioration of the inorganic phosphor powder becomes remarkable. tendency. Therefore, a wavelength conversion member which lowers the softening point by containing an alkali metal element in the glass powder composition has been proposed (for example, see Patent Document 4). Since the wavelength converting member can be produced by firing at a relatively low temperature, deterioration of the inorganic phosphor powder at the time of firing can be suppressed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2000-208815

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-258308

[Patent Document 3] Japanese Patent No. 4985541

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2007-302858

However, the above-described wavelength converting member containing an alkali metal element in the glass matrix has a problem that the luminous intensity tends to decrease with time. As the output of light sources such as LEDs or LDs has further increased in recent years, the temporal decrease in luminous intensity has become more remarkable.

Accordingly, it is an object of the present invention to provide a wavelength conversion member which has a small decrease in luminous intensity with time when a light of an LED or an LD is irradiated.

The wavelength conversion member of the present invention is characterized by comprising a sintered body comprising (a) a glass powder containing an alkali metal element and a polyvalent element as a glass composition, and (b) a mixed powder of an inorganic phosphor powder. In the present invention, the term "multivalent element" means an element capable of using a plurality of valences.

As described above, if a wavelength conversion member containing an alkali metal element in a glass matrix When the LED of the high output LED or LD is irradiated, the luminous intensity tends to decrease with time. The inventors of the present invention presume the following for detailed reasons.

If the excitation light is irradiated to the glass substrate containing the alkali metal element in the composition, the electrons present in the outermost shell of the oxygen ions in the glass matrix are excited by the energy of the excitation light, and are separated from the oxygen ions, and a part of the alkali in the glass matrix. The ions combine to form a coloring center (here, a vacancy is formed after the alkali ions are detached). On the other hand, the holes generated by the electrons falling off move in the glass matrix, and some of them are trapped in the vacancies formed after the alkali ions are detached, thereby forming a coloring center. It is considered that the coloring centers formed in the glass substrate become absorption sources of excitation light or fluorescence, and the light-emitting intensity of the wavelength conversion member is lowered.

Therefore, in order to suppress the above phenomenon, the wavelength conversion member of the present invention contains a multivalent element in the glass composition. If there is an ion of a polyvalent element whose valence is easily changed in the vicinity of the coloring center in which the above-mentioned hole is captured, the multivalent element ion imparts electrons to the hole and quenches the hole. Here, if the color center capturing electrons exists in the vicinity of the polyvalent element ions, the multivalent element ions return to the initial electronic state by taking electrons from the coloring center. As a result, it is considered that the multivalent element ion system acts as an electron carrier to capture electrons from the center of color capturing electrons, and imparts the electrons to the color center of the electron deficiency, thereby recombining electrons and holes. As a result, the electrons and holes generated in the glass matrix can be inhibited from acting on the alkali ions or vacancies in the glass matrix, and the luminescence intensity of the wavelength converting member can be suppressed from decreasing with time.

In the wavelength conversion member of the present invention, it is preferable that the polyvalent element is at least one selected from the group consisting of Ce, As, Mo, and W.

In the wavelength conversion member of the present invention, it is preferable that the glass powder contains 0.1 to 35% of Li ₂ O+Na ₂ O+K ₂ O in terms of mol% of the following oxide.

In the wavelength conversion member of the present invention, it is preferable that the glass powder contains 0.001 to 10% of CeO ₂ + As ₂ O ₃ + MoO ₂ + WO _{3 in terms} of mol% of the following oxide.

In the wavelength conversion member of the present invention, it is preferable that the glass powder contains 30 to 80% of SiO ₂ , 1 to 40% of B ₂ O ₃ , and 0.1 to 35% by mol% of the following oxides. Li ₂ O+Na ₂ O+K ₂ O, 0.1 to 45% of MgO+CaO+SrO+BaO, and 0.001 to 10% of CeO ₂ +As ₂ O ₃ +MoO ₂ +WO ₃ .

In the wavelength conversion member of the present invention, it is preferable that the glass powder contains 30 to 80% of SiO ₂ , 1 to 55% of B ₂ O ₃ , and 0 to 20% by mol% of the following oxides. Li ₂ O, 0 to 25% of Na ₂ O, 0 to 25% of K ₂ O, 0.1 to 35% of Li ₂ O+Na ₂ O+K ₂ O, and 0.001 to 10% of CeO ₂ +As ₂ O ₃ +MoO ₂ +WO ₃ .

In the wavelength conversion member of the present invention, it is preferable that the inorganic phosphor powder is selected from the group consisting of a nitride phosphor, an oxynitride phosphor, an oxide phosphor, a sulfide phosphor, and an oxysulfide fluorite. At least one of a light body, a halide phosphor, and an aluminate phosphor.

The wavelength conversion member of the present invention is characterized in that it is obtained by dispersing an inorganic phosphor powder in a matrix containing a sintered body of an alkali metal element and a polyvalent element as a glass powder of a glass composition.

A light-emitting device according to the present invention includes any one of the wavelength conversion members described above and a light source that emits excitation light to the wavelength conversion member.

According to the present invention, it is possible to provide a wavelength conversion member in which the luminous intensity is less reduced with time when the light of the LED or the LD is irradiated.

1‧‧‧Lighting device

2‧‧‧wavelength conversion member

3‧‧‧Light source

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an embodiment of a light-emitting device of the present invention.

The wavelength conversion member of the present invention is characterized by comprising a sintered body comprising (a) a glass powder containing an alkali metal element and a polyvalent element as a glass composition, and (b) a mixed powder of an inorganic phosphor powder. Hereinafter, each constituent component will be described in detail.

The glass powder has a function as a medium for stably holding the inorganic phosphor powder in the wavelength conversion member of the present invention. Here, according to the composition of the glass powder, baking There is a difference in reactivity with the inorganic phosphor powder at the time of firing, and therefore it is preferred to select a glass composition suitable for the inorganic phosphor powder to be used.

In order to lower the softening point, the glass powder contains an alkali metal element (at least one selected from the group consisting of Li, Na, and K) as a glass composition. Specifically, the glass powder preferably contains 0.1 to 35% of Li ₂ O+Na ₂ O+K ₂ O, more preferably 1 to 25%, more preferably 1% to 25%, more preferably It contains 2~20%. When the content of Li ₂ O+Na ₂ O+K ₂ O is too small, it is difficult to obtain the above effects, and if it is too large, the chemical durability is liable to lower. Further, as described below, the content of Li ₂ O, Na ₂ O and K ₂ O is preferably set to an appropriate range in accordance with the glass composition system.

Further, by causing the glass powder to contain a polyvalent element, it is possible to suppress a decrease in the luminous intensity of the wavelength conversion member over time. The polyvalent element may be at least one selected from the group consisting of Ce, As, Mo, and W. In particular, Ce can remarkably suppress the decrease in luminous intensity with time, and further, the glass powder itself is difficult to be colored, which is preferable.

The glass powder preferably contains 0.001 to 10% of CeO ₂ + As ₂ O ₃ + MoO ₂ + WO ₃ , more preferably 0.01 to 5%, and more preferably contains 0% by mole of the following oxides. 0.1~3%. When the content of CeO ₂ + As ₂ O ₃ + MoO ₂ + WO ₃ is too small, it becomes difficult to obtain the above effects. On the other hand, if it is too much, the glass powder itself will be colored, and the luminous intensity tends to be lowered. Further, the content of each polyvalent element is also preferably set to the above range.

Further, the glass powder preferably contains at least one selected from the group consisting of SiO ₂ , B ₂ O ₃ , P ₂ O ₅ , Bi ₂ O ₃ and TeO ₂ in an amount of 10 to 99 mol%. Specifically, SiO ₂ -B ₂ O ₃ -RO (R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) -R' ₂ O (R' is selected from Li, Na, and K. At least one type of glass, SnO-P ₂ O ₅ -R' ₂ O-based glass, SiO ₂ -B ₂ O ₃ -R' ₂ O-based glass, SiO ₂ -B ₂ O ₃ -ZnO-R' ₂ O-based glass, etc.

The SiO ₂ -B ₂ O ₃ -RO-R' ₂ O-based glass preferably contains 30 to 80% of SiO ₂ and 1 to 40% of B ₂ O in terms of mol% of the following oxides. ₃ , 0.1 to 35% of Li ₂ O+Na ₂ O+K ₂ O, 0.1 to 45% of MgO+CaO+SrO+BaO, and 0.001 to 10% of CeO ₂ +As ₂ O ₃ +MoO ₂ +WO ₃ people. Hereinafter, the reason why the glass composition is thus limited will be described.

SiO ₂ forms a component of the glass network. The content of SiO ₂ is preferably from 30 to 80%, more preferably from 40 to 60%. When the content of SiO ₂ is too small, the chemical durability tends to be lowered. On the other hand, when the content of SiO ₂ is too high, the softening point becomes high. Therefore, in order to sufficiently sinter, it is necessary to perform high-temperature baking. As a result, the inorganic phosphor powder is easily deteriorated at the time of baking.

B ₂ O ₃ is a component which has a large effect of lowering the melting temperature and improving the meltability. The content of B ₂ O ₃ is preferably from 1 to 40%, more preferably from 5 to 30%. If the content of B ₂ O ₃ is too small, it becomes difficult to obtain the above effects. On the other hand, when the content of B ₂ O ₃ is too large, the chemical durability tends to be lowered.

Li ₂ O, Na ₂ O and K ₂ O are components which lower the softening point. The content (total amount) of Li ₂ O, Na ₂ O and K ₂ O is preferably from 0.1 to 35%, more preferably from 1 to 25%, still more preferably from 2 to 20%. When the content of these components is too small, the softening point is hard to be lowered. On the other hand, if the components are too large, chemical durability or weather resistance is likely to be lowered.

Further, preferred ranges of the contents of the respective components of Li ₂ O, Na ₂ O and K ₂ O are as follows. The content of Li ₂ O is preferably from 0 to 10%, more preferably from 0.1 to 5%. The content of Na ₂ O is preferably from 0 to 15%, more preferably from 0.1 to 10%. The content of K ₂ O is preferably from 0 to 15%, more preferably from 0.1 to 10%.

MgO, CaO, SrO, and BaO are components which lower the melting temperature and improve the meltability. Further, BaO also has an effect of suppressing the reaction with the inorganic phosphor powder. The content (total amount) of MgO, CaO, SrO and BaO is preferably from 0.1 to 45%, more preferably from 1 to 40%, still more preferably from 2 to 35%. When the content of these components is too small, it tends to be difficult to obtain the above effects. On the other hand, if the content is too large, the chemical durability tends to be lowered.

Further, preferred ranges of the contents of the respective components of MgO, CaO, SrO and BaO are as follows. The content of MgO is preferably from 0 to 10%, more preferably from 0 to 5%. The content of CaO is preferably from 0 to 30%, more preferably from 0 to 20%. The content of SrO is preferably 0-20%, more preferably 0~ 10%. The content of BaO is preferably from 0 to 40%, more preferably from 0.1 to 30%.

The total amount and individual content of CeO ₂ , As ₂ O ₃ , MoO ₂ , and WO ₃ are as described above.

The glass powder may contain the following components in addition to the above components.

The Al ₂ O ₃ system is a component that enhances chemical durability. The content of Al ₂ O ₃ is preferably from 0 to 20%, more preferably from 1 to 18%. When the content of Al ₂ O ₃ is too large, the meltability tends to decrease.

ZnO is a component which lowers the melting temperature and improves the meltability. The content of ZnO is preferably from 0 to 20%, more preferably from 0.1 to 10%. If the content of ZnO is too large, chemical durability is likely to be lowered.

Further, in order to enhance chemical durability and the like, it may contain up to 15% of Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ , Bi ₂ O ₃ or ZrO. ₂ each.

As the SnO-P ₂ O ₅ -R' ₂ O-based glass, for example, it is preferable to contain 35 to 80% of SnO, 5 to 40% of P ₂ O ₅ , and 0 to 30% of B _{2 in terms of} mol%. O ₃ , 0.1 to 5% of Li ₂ O+Na ₂ O+K ₂ O, and 0.001 to 10% of CeO ₂ +As ₂ O ₃ +MoO ₂ +WO ₃ . Hereinafter, the reason why the glass composition is thus limited will be described.

SnO forms a component of the glass network and lowers the softening point. The content of SnO is preferably from 35 to 80%, more preferably from 45 to 75%. When the content of SnO is too small, the softening point becomes high, or the weather resistance tends to decrease. On the other hand, when the content of SnO is too large, the devitrification substance due to Sn is precipitated, and the transmittance tends to be lowered. As a result, the light-emitting intensity of the wavelength conversion member is liable to lower. Moreover, it becomes difficult to vitrify.

P ₂ O ₅ forms a component of the glass network. The content of P ₂ O ₅ is preferably from 5 to 40%, more preferably from 10 to 30%. When the content of P ₂ O ₅ is too small, it becomes difficult to vitrify. On the other hand, when the content of P ₂ O ₅ is too large, the softening point becomes high, and the weather resistance tends to be remarkably lowered.

The B ₂ O ₃ system enhances weather resistance and promotes phase separation components. Moreover, it also has an effect of stabilizing the glass. The content of B ₂ O ₃ is preferably from 0 to 30%, more preferably from 1 to 25%. When the content of B ₂ O ₃ is too large, the weather resistance is liable to lower. Further, there is a tendency that the softening point is excessively high.

Li ₂ O, Na ₂ O and K ₂ O are components which lower the softening point. The content (total amount) of Li ₂ O, Na ₂ O and K ₂ O is preferably from 0.1 to 5%, more preferably from 1 to 4%. If the content of these components is too small, the softening point is hard to be lowered. On the other hand, if these components are too much, chemical durability will fall easily. Further, the phase separation property is excessively large, and the light scattering loss tends to increase. The content of each component of Li ₂ O, Na ₂ O and K ₂ O is preferably 0 to 5%, more preferably 0.1 to 4%, still more preferably 1 to 4%.

The total amount and individual content of CeO ₂ , As ₂ O ₃ , MoO ₂ , and WO ₃ are as described above.

Moreover, in order to improve the meltability or to lower the softening point, it is easy to carry out low-temperature baking, and may contain up to 5% by weight of MgO, CaO, SrO or BaO in addition to the above components. Further, in order to enhance chemical durability and the like, it may contain up to 15% of Al ₂ O ₃ , ZrO ₂ , ZnO, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , Bi ₂ O ₃ , TeO. ₂ or La ₂ O ₃ each.

As the SiO ₂ -B ₂ O ₃ -R' ₂ O-based glass, for example, it is preferable to contain 30 to 80% of SiO ₂ , 1 to 55% of B ₂ O ₃ , and 0 to 20% by mol%. Li ₂ O, 0 to 25% of Na ₂ O, 0 to 25% of K ₂ O, 0.1 to 35% of Li ₂ O+Na ₂ O+K ₂ O, and 0.001 to 10% of CeO ₂ +As ₂ O ₃ +MoO ₂ +WO ₃ .

Further, in order to improve the meltability, MgO, CaO, SrO, and BaO may be contained in an amount of up to 30% in addition to the above components. In addition, in order to improve the meltability, it may contain up to 10% ZnO, up to 5% P ₂ O ₅ , and may contain up to 10% of Al ₂ O ₃ and up to 15% of Ta in order to improve chemical durability. ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ or La ₂ O ₃ each.

As the SiO ₂ -B ₂ O ₃ -ZnO-R' ₂ O-based glass, for example, it is preferably 5 to 50% of SiO ₂ , 10 to 55% of B ₂ O ₃ , and 30 to 80% by mol%. % of ZnO, 0-20% of Li ₂ O, 0 to 20% of Na ₂ O, 0 to 20% of K ₂ O, 0.1 to 25% of Li ₂ O+Na ₂ O+K ₂ O, 0~ 10% of MgO, 0 to 10% of CaO, 0 to 10% of SrO, 0 to 10% of BaO, and 0.001 to 10% of CeO ₂ + As ₂ O ₃ + MoO ₂ + WO ₃ .

Further, in order to improve chemical durability, in addition to the above components, it may contain up to 5% of Al ₂ O ₃ , up to 15% of Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ or La _{2 .} O ₃ each.

The particle diameter of the glass powder is not particularly limited. For example, the maximum particle diameter D ₉₉ is preferably 200 μm or less (especially 150 μm or less, and further 105 μm or less), and the average particle diameter D ₅₀ is 0.1 μm or more (especially 1 μm or more, and further 2μm or more). When the maximum particle diameter D _{99 of} the glass powder is too large, the excitation light becomes difficult to scatter in the obtained wavelength conversion member, and the luminous efficiency is liable to lower. Further, when the average particle diameter D _{50 is} too small, the excitation light is excessively scattered in the obtained wavelength conversion member, and the luminous efficiency is liable to lower.

Further, in the present invention, the average particle diameter D ₅₀ and the maximum particle diameter D ₉₉ refer to values measured by a laser diffraction method.

The inorganic phosphor powder is not particularly limited as long as it is generally commercially available. For example, a nitride phosphor powder, an oxynitride phosphor powder, an oxide phosphor powder (including a garnet phosphor powder such as YAG (Yttrium Aluminium Garnet) phosphor powder) ), sulfide phosphor powder, oxysulfide phosphor powder, halide phosphor powder (halide phosphate), and aluminate phosphor powder. Among the inorganic phosphor powders, the nitride phosphor powder, the oxynitride phosphor powder, and the oxide phosphor powder have high heat resistance and are relatively difficult to deteriorate during baking, which is preferable. Further, the nitride phosphor powder and the oxynitride phosphor powder have a characteristic that a near-ultraviolet-blue excitation light is converted into a broad wavelength region such as green to red, and the luminescence intensity is relatively high. Therefore, the nitride phosphor powder and the oxynitride phosphor powder are particularly effective as the inorganic phosphor powder used for the wavelength conversion member for a white LED element.

Examples of the inorganic phosphor powder include an excitation band at a wavelength of 300 to 500 nm and an emission peak at a wavelength of 380 to 780 nm, and particularly blue (wavelength: 440 to 480 nm) and green color (wavelength: 500 to 540 nm). Yellow (wavelength 540~595nm) or red (wavelength 600~700nm) illuminator.

The inorganic phosphor powder which emits blue fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm is exemplified by (Sr, Ba) MgAl ₁₀ O ₁₇ :Eu ²⁺ , (Sr,Ba) ₃ MgSi. ₂ O ₈ : Eu ²⁺ and the like.

The inorganic phosphor powder that emits green fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm may be SrAl ₂ O ₄ :Eu ²⁺ , SrBaSiO ₄ :Eu ²⁺ , Y ₃ (Al, Gd) ₅ O ₁₂ :Ce ³⁺ , SrSiO _n :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.

The inorganic phosphor powder that emits green fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm, and examples thereof 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.

The inorganic phosphor powder which emits yellow fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm is exemplified by La ₃ Si ₆ N ₁₁ :Ce ³⁺ or the like.

Examples of the inorganic phosphor powder which 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⁺ .

The inorganic phosphor powder which emits red fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 to 440 nm, and examples thereof include CaGa ₂ S ₄ :Mn ²⁺ , MgSr ₃ Si ₂ O ₈ :Eu ²⁺ , Mn ^{2 . +} , Ca ₂ MgSi ₂ O ₇ : Eu ²⁺ , Mn ²⁺ and the like.

Examples of the inorganic phosphor powder that emits 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⁺ , and (Ca,Sr) ₂ Si ₅ N _{8 .} :Eu ²⁺ , α-SiAlON: Eu ^2+, and the like.

Further, a plurality of inorganic phosphor powders may be mixed and used depending on the wavelength region of the excitation light or the light emission. For example, when the white light is obtained by irradiating the excitation light in the ultraviolet region, the inorganic phosphor powder emitting blue, green, yellow, and red phosphorescence may be used by mixing and mixing.

If the content of the inorganic phosphor powder in the wavelength conversion member is too large, it becomes difficult Sintering, or the tendency of the porosity to become large. As a result, the wavelength conversion member obtained has a problem that it is difficult to efficiently irradiate the inorganic phosphor powder with excitation light, or the mechanical strength is easily lowered. On the other hand, if the content of the inorganic phosphor powder is too small, it becomes difficult to obtain a desired luminescent intensity. In this regard, the content of the inorganic phosphor powder in the wavelength converting member is preferably from 0.01 to 50% by mass, more preferably from 0.05 to 40%, still more preferably from 0.1 to 30% by mass%. Make adjustments.

In addition, the wavelength conversion member for the purpose of reflecting the fluorescent light generated in the wavelength conversion member to the incident side of the excitation light and mainly extracting only the fluorescence to the outside may also be an inorganic phosphor for maximizing the emission intensity. The content of the powder is made large (for example, 50% to 80% by mass%, and further 55 to 75%), and is not limited to the above content.

The wavelength conversion member of the present invention is produced by firing a mixed powder of an alkali metal element and a polyvalent element as a glass powder of a glass composition. Thereby, a wavelength conversion member obtained by dispersing an inorganic phosphor powder in a matrix containing a sintered body of an alkali metal element and a polyvalent element as a glass powder of a glass composition is obtained.

The baking temperature is appropriately adjusted within a range of ±150 ° C, preferably within ±100 ° C of the softening point of the glass powder. When the baking temperature is too low, the glass powder does not sufficiently flow, and it is difficult to obtain a dense sintered body. On the other hand, when the baking temperature is too high, the inorganic phosphor powder is melted into the glass powder to lower the luminescent intensity. Alternatively, the component contained in the inorganic phosphor powder is diffused into the glass powder and colored to lower the luminescence intensity.

Further, the baking is preferably carried out in a reduced pressure environment. Specifically, the firing environment is preferably less than 1.013 × 10 ⁵ Pa, more preferably 1,000 Pa or less, still more preferably 400 Pa or less. Thereby, the amount of bubbles remaining in the wavelength converting member can be reduced. As a result, the light scattering factor in the wavelength conversion member can be reduced, and the luminous efficiency can be improved. Furthermore, the entire calcination step may be carried out in a reduced pressure environment, for example, the calcination step may be carried out in a reduced pressure environment, and the temperature rise step or the temperature decrease step before and after the calcination step may be carried out in a non-reduced environment (for example, at atmospheric pressure). In progress.

The shape of the wavelength conversion member of the present invention is not particularly limited, and may be, for example, a plate shape, a column shape, a spherical shape, a hemispherical shape, or a hemispherical dome shape, and may be formed not only for a member having a specific shape but also for forming a glass. A film-like shape on the surface of a substrate such as a substrate or a ceramic substrate.

Fig. 1 shows an embodiment of a 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 excitation light L _in . The excitation light L _in incident on the wavelength conversion member 2 is converted into light of another wavelength, and is emitted as L _out from the side opposite to the light source 3. At this time, it is also possible to emit the combined light of the wavelength-converted light and the excitation light that has not been converted by the wavelength conversion.

[Examples]

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

(1) Production of glass powder

Table 1 shows the composition of the glass powder used in the present example.

First, the raw materials were prepared in such a manner as to have the composition shown in Table 1. The raw material is melted in a platinum crucible at a temperature of 800 to 1500 ° C for 1 to 2 hours to vitrify, and the molten glass is discharged from a pair of cooling rolls to form a film. The film-shaped glass was pulverized by a ball mill, and classified to obtain a glass powder having an average particle diameter D ₅₀ of 2.5 μm.

The density and softening point of each glass powder are measured by using a sample obtained by molding molten glass into a block shape or a column shape according to each measurement and annealing. The softening point is a fiber elongation method using a viscosity of 10 ^7.6 dPa‧s. Density is determined by the Archimedes method.

(2) Production of wavelength conversion member

Tables 2 to 4 show examples of the present invention (sample Nos. 2 to 3, 5 to 6, 8 to 9, 11 to 12, 14 to 15, 17 to 18, 20 to 21, 23 to 24, and 26 to 27). And comparative examples (sample No. 1, 4, 7, 10, 13, 16, 19, 22, 25).

With respect to the glass powders shown in Table 1, in Table 2, a specific amount of Y ₃ (Al, Gd) ₅ O ₁₂ :Ce ³⁺ (YAG) phosphor powder was mixed, and in Table 3, a specific amount was (Ca,Sr) ₂ Si ₅ N ₈ :Eu ²⁺ (SCASN) phosphor powder is mixed, and in Table 4, a specific amount of α-SiAlON:Eu ²⁺ (α-SiAlON) phosphor powder is mixed. Thereby obtaining a mixed powder. The mixed powder was pressure molded by a mold to prepare a cylindrical preform having a diameter of 1 cm. The sintered body obtained by firing the preform at the temperature described in the table was processed to obtain a wavelength conversion member of 1.2 mm square and 0.2 mm thick. The obtained wavelength conversion member was placed on an LED wafer having an emission wavelength of 445 nm, energized at 700 mA in an integrating sphere, and continuously irradiated for 100 hours. The luminescence spectrum was measured using a general-purpose luminescence spectrometer to measure the energy distribution spectrum of light emitted from the upper surface of the wavelength conversion member. The total luminous flux value is calculated by multiplying the obtained luminescence spectrum by a standard specific luminosity. The total luminous flux value was calculated before irradiation and after 100 hours of irradiation. The rate of change of the total luminous flux value is expressed by the value (%) obtained by dividing the total luminous flux value after 100 hours of irradiation by the total luminous flux value before irradiation and multiplying by 100, and is shown in Tables 2 to 4.

As is clear from Tables 2 to 4, the wavelength conversion member of the example did not substantially decrease the total luminous flux value even after the excitation light was irradiated for 100 hours. On the other hand, in the wavelength conversion member of the comparative example, the total luminous flux value was largely lowered after the excitation light was irradiated for 100 hours.

[Industrial availability]

The wavelength conversion member of the present invention is used as general illumination or special illumination such as white LED (example A constituent member such as a projector light source or a car headlight source is preferable.

Claims (9)

A wavelength conversion member comprising a sintered body comprising (a) a glass powder containing an alkali metal element and a polyvalent element as a glass composition, and (b) a mixed powder of an inorganic phosphor powder. The wavelength conversion member according to claim 1, wherein the multivalent element is at least one selected from the group consisting of Ce, As, Mo, and W. The wavelength conversion member according to claim 1 or 2, wherein the glass powder contains 0.1 to 35% of Li ₂ O+Na ₂ O+K ₂ O in terms of mol% of the following oxide. The wavelength conversion member according to any one of claims 1 to 3, wherein the glass powder contains 0.001 to 10% of CeO ₂ + As ₂ O ₃ + MoO ₂ + WO _{3 in terms} of mol% of the following oxide. The wavelength conversion member according to any one of claims 1 to 4, wherein the glass powder contains 30 to 80% of SiO ₂ , 1 to 40% of B ₂ O ₃ , 0.1 in terms of mol% of the following oxides. ~35% of Li ₂ O+Na ₂ O+K ₂ O, 0.1 to 45% of MgO+CaO+SrO+BaO, and 0.001 to 10% of CeO ₂ +As ₂ O ₃ +MoO ₂ +WO ₃ . The wavelength conversion member according to any one of claims 1 to 4, wherein the glass powder contains 30 to 80% of SiO ₂ and 1 to 55% of B ₂ O ₃ , 0 in terms of mol% of the following oxides. ~20% Li ₂ O, 0~25% Na ₂ O, 0~25% K ₂ O, 0.1~35% Li ₂ O+Na ₂ O+K ₂ O, and 0.001~10% CeO ₂ + As ₂ O ₃ + MoO ₂ + WO ₃ . The wavelength conversion member according to any one of claims 1 to 6, wherein the inorganic phosphor powder is selected from the group consisting of a nitride phosphor, an oxynitride phosphor, an oxide phosphor, a sulfide phosphor, At least one of an oxysulfide phosphor, a halide phosphor, and an aluminate phosphor. A wavelength conversion member obtained by dispersing an inorganic phosphor powder in a matrix containing a sintered body of an alkali metal element and a polyvalent element as a glass powder. A light-emitting device comprising the wavelength conversion member according to claim 7 or 8 and a light source that irradiates the wavelength conversion member with excitation light.