JP5807780B2 - Wavelength converting member and light emitting device using the same - Google Patents

Description

  The present invention relates to a wavelength conversion member used as a constituent member of a light emitting device such as a white LED.

  In recent years, light-emitting devices such as white LEDs have been actively developed. White LEDs are characterized by low power consumption and long life compared to incandescent lamps and fluorescent lamps, and are being used as backlights for mobile phones and digital cameras. In the future, as a next-generation light source that replaces incandescent and fluorescent lamps, it is expected to be applied to lighting applications.

  The white LED is composed of, for example, an LED chip 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 excitation light from the LED chip and emits light (fluorescence) having a wavelength different from that of the excitation light. On the other hand, some of the excitation light passes through the wavelength conversion member without contributing to wavelength conversion. These lights are mixed to obtain white light.

  Incidentally, white LEDs are required to have higher luminance (higher power) depending on applications. In the conventional method of dispersing the inorganic phosphor powder in the resin matrix, there is a problem that the resin matrix is discolored by heat from the LED chip and the luminance is lowered when used for a long time. In addition, when a resin containing an inorganic phosphor powder is applied on the LED chip, there is a problem that it is difficult to adjust the thickness uniformly and chromaticity variations are likely to occur.

  In order to solve these problems, a method has been proposed in which the inorganic phosphor powder is dispersed in a glass matrix to completely mineralize the wavelength conversion member (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, the white LED can be exposed to a long-time high temperature environment (for example, 150 ° C. for 600 hours) or a long-time high temperature and high humidity environment (for example, temperature 85 ° C. and humidity 85% for 2000 hours). The light emission characteristics hardly change, and there is almost no coloring or deterioration even when exposed to ultraviolet rays of sunlight for a long time. Furthermore, since it is excellent in workability, it is possible to suppress chromaticity variations caused by thickness non-uniformity.

JP 2005-11933 A JP 2003-258308 A

  A wavelength conversion member obtained by dispersing inorganic phosphor powder in a glass matrix has a problem that the excitation light of the LED goes straight without being sufficiently scattered inside the wavelength conversion member. In particular, when the difference in refractive index between the glass matrix and the inorganic phosphor powder is small, the tendency becomes remarkable because light scattering at the interface between the two is reduced. When the straight component of the excitation light is large, the diffusion of light emitted from the white LED varies, and the chromaticity tends to be different between a range close to the optical axis of the excitation light source and a position away from the optical axis. Moreover, since the frequency with which the excitation light strikes the inorganic phosphor powder is reduced, the total luminous flux value tends to be lowered.

  Increasing the content of the inorganic phosphor powder in the wavelength conversion member increases the amount of light scattering at the interface between the glass matrix and the inorganic phosphor powder as a whole and improves the diffusion characteristics, but the chromaticity is desired. Another problem will arise that will deviate from this range. In addition, when the amount of the inorganic phosphor powder is increased, the inorganic phosphor powder itself blocks the excitation light excessively, and the total luminous flux value tends to decrease.

  In view of the above, the present invention is a wavelength conversion member in which inorganic phosphor powder is dispersed in a glass matrix, having a desired chromaticity range, excellent light diffusion characteristics, and a wavelength with a high total luminous flux value. It is an object to provide a conversion member.

  As a result of intensive studies, the wavelength conversion member in which the inorganic phosphor powder is dispersed in the glass matrix, the present inventors have a specific structure, so that even if the content of the inorganic phosphor powder is small, It has been found that the diffusion characteristics of excitation light are good and the total luminous flux value is high, and is proposed as the present invention.

  That is, the present invention is a wavelength conversion member composed of a sintered body of a mixed powder containing glass powder and inorganic phosphor powder, and has a heterogeneous layer having a composition different from that of the glass powder at the grain boundary of the glass powder. The present invention relates to a wavelength conversion member.

  As described above, in the wavelength conversion member in which the inorganic phosphor powder is dispersed in the glass matrix, if there are many linear components of the excitation light from the LED chip, the diffusion of the irradiation light of the white LED will vary, and the irradiation angle There is a problem that chromaticity differs depending on the type. Therefore, if the wavelength conversion member is made of a sintered powder of mixed powder containing glass powder and inorganic phosphor powder, and has a heterogeneous layer having a composition different from that of the glass powder at the grain boundary of the glass powder, The heterogeneous layer functions as a scatterer to increase the scattering of excitation light, and as a result, a wavelength conversion member having excellent diffusion characteristics and a high total luminous flux value can be obtained.

  2ndly, it is preferable that the thickness of a heterogeneous layer is 0.001-5 micrometers in the wavelength conversion member of this invention.

  According to the said structure, excitation light is easily scattered by a heterogeneous layer, it becomes easy to obtain the wavelength conversion member which is excellent in a diffusion characteristic, and has a high total light flux value.

  Third, the wavelength conversion member of the present invention preferably has a refractive index difference between the glass powder and the heterogeneous layer of 0.001 to 0.5.

  Fourthly, the wavelength conversion member of the present invention preferably uses glass powder having a heterogeneous layer on the surface as a raw material.

  According to the said structure, it becomes possible to produce easily the wavelength conversion member which has the heterogeneous layer which consists of a composition different from glass powder in the grain boundary of glass powder.

  Fifth, the wavelength conversion member of the present invention preferably has a parallel light transmittance measured in accordance with JIS K7105 of 10% or less and a haze of 80% or more.

  Sixth, the wavelength conversion member of the present invention preferably contains 0.1 to 10% by mass of ceramic powder.

  According to the said structure, the effect which scatters excitation light becomes larger, it becomes easy to obtain the wavelength conversion member which is excellent in a diffusion characteristic, and has a high total light flux value.

  Seventhly, in the wavelength conversion member of the present invention, the inorganic phosphor powder is made of oxide, nitride, oxynitride, sulfide, oxysulfide, rare earth sulfide, aluminate chloride, or halophosphate chloride. It is preferable.

  Eighth, the present invention relates to a light emitting device comprising any one of the wavelength conversion members and a light source that irradiates the wavelength conversion member with excitation light.

  According to the present invention, it is possible to provide a wavelength conversion member that has a desired chromaticity range, is excellent in diffusion characteristics, and has a high total luminous flux value.

  The wavelength conversion member of the present invention is made of a sintered body of mixed powder containing glass powder and inorganic phosphor powder.

  The glass powder has a role as a medium for stably holding the inorganic phosphor powder. In addition, since the reactivity with the inorganic phosphor powder varies depending on the glass composition of the glass powder, it is preferable to select a glass composition suitable for the inorganic phosphor powder to be used.

Examples of the glass powder include SiO ₂ —B ₂ O ₃ glass, SnO—P ₂ O ₅ glass, TeO ₂ glass, Bi ₂ O ₃ glass, and the like.

The SiO ₂ -B ₂ O ₃ based glass, for example, in mol% _{composition, SiO 2 30~80%, B 2} O 3 1~40%, 0~10% MgO, CaO 0~30%, SrO 0~ 20%, BaO 0~40%, MgO + CaO + SrO + BaO 5~45%, Al 2 O 3 0~20%, those containing 0 to 20% ZnO preferred. The reason for limiting the glass composition in this way will be described below.

SiO ₂ is a component that forms a glass skeleton. The content of SiO ₂ is preferably 30 to 80%, particularly preferably 40 to 60%. When the content of SiO ₂ is too small, chemical durability tends to decrease. On the other hand, if the content of SiO ₂ is too large, the firing temperature becomes a high temperature, inorganic phosphor powder is likely to deteriorate.

B ₂ O ₃ is a component having a great effect of improving the meltability by lowering the melting temperature. The content of B ₂ O ₃ is preferably 1 to 40%, 5 to 35%, particularly preferably 10 to 30%. If the content of B ₂ O ₃ is too small, the effect is difficult to obtain. On the other hand, when the content of B ₂ O ₃ is too large, chemical durability tends to decrease.

  MgO is a component that improves the meltability by lowering the melting temperature. The content of MgO is preferably 0 to 10%, particularly preferably 0.1 to 5%. When the content of MgO is too large, chemical durability tends to decrease.

  CaO is a component that improves the meltability by lowering the melting temperature. The CaO content is preferably 0 to 30%, particularly preferably 3 to 20%. When there is too much content of CaO, it exists in the tendency for chemical durability to fall.

  SrO is a component that improves the meltability by lowering the melting temperature. The SrO content is preferably 0 to 20%, 0 to 10%, particularly preferably 0.1 to 5%. When the content of SrO is too large, chemical durability tends to decrease.

  BaO is a component that improves the meltability by lowering the melting temperature and suppresses the reaction with the inorganic phosphor powder. The BaO content is preferably 0 to 40%, particularly preferably 5 to 30%. When there is too much content of BaO, it exists in the tendency for chemical durability to fall.

  In order to improve the meltability without reducing the chemical durability, the total amount of MgO, CaO, SrO and BaO is preferably 5 to 45%, particularly 10 to 40%. If the total amount of these components is too small, it will be difficult to obtain the effect of improving the meltability. On the other hand, if the total amount is too large, the chemical durability tends to decrease.

Al ₂ O ₃ is a component that improves chemical durability. The content of Al ₂ O ₃ is 0 to 20%, preferably 1 to 18%. When the content of Al ₂ O ₃ is too large, there is a tendency that the meltability decreases.

  ZnO is a component that improves the meltability by lowering the melting temperature. It also has the effect of promoting phase separation. Improvement of the diffusion property of excitation light can be expected by the phase separation of the glass. The content of ZnO is preferably 0 to 20%, particularly preferably 1 to 18%. When there is too much content of ZnO, it exists in the tendency for chemical durability to fall.

In addition to the above components, Li ₂ O, Na ₂ O or K ₂ O can be added up to 5% in total in order to improve the meltability or lower the softening point to facilitate low-temperature firing. . In addition, P ₂ O ₅ is increased to 5% for improving the meltability, and Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , La ₂ O for improving the chemical durability. ₃ , Y ₂ O ₃ , CeO ₂ , Sb ₂ O ₃ , SnO ₂ , Bi ₂ O ₃ , TeO ₂ or ZrO ₂ may be added up to 15% in total.

The _SnO-P 2 _{O 5} based glass powder, in mol% as a glass _{composition, SnO 35~80%, P 2 O} 5 5~40%, those containing 2 O 3 0 to 30% _B is preferred. The reason for limiting the glass composition in this way will be described below.

  SnO is a component that forms a glass skeleton and lowers the softening point. The SnO content is preferably 35 to 80%, particularly 45 to 75%. When there is too little content of SnO, there exists a tendency for a softening point to raise or for a weather resistance to fall. On the other hand, when there is too much content of SnO, the devitrification pattern resulting from Sn exists and it exists in the tendency for the transmittance | permeability to fall, As a result, the emitted light intensity of a wavelength conversion member member falls easily. Moreover, it becomes difficult to vitrify.

P ₂ O ₅ is a component that forms a glass skeleton. The content of P ₂ O ₅ is preferably 5 to 40%, particularly preferably 10 to 30%. When the content of P ₂ O ₅ is too small, it is difficult to vitrify. On the other hand, when the content of P ₂ O ₅ is too large, or the softening point rises, there is a tendency that weather resistance is significantly lowered.

B ₂ O ₃ is a component for improving weather resistance and a component for promoting phase separation. It also has the effect of stabilizing the glass. The content of B ₂ O ₃ is preferably 0 to 30%, particularly preferably 1 to 25%. If the B ₂ O ₃ content is too large, the weather resistance tends to lower. Also, the softening point tends to increase.

In addition to the above components, the total amount of CaO, MgO, SrO or BaO can be up to 5%, Li ₂ O, Na _{2 in} order to improve the meltability or lower the softening point to facilitate low-temperature firing. O or K ₂ O can be added up to 5% in total. In addition, in order to improve chemical durability, Al ₂ O ₃ , ZrO, ZnO, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , La ₂ O ₃ , Y ₂ O ₃ , CeO ₂ , Sb ₂ O ₃ , Bi ₂ O ₃ or TeO ₂ may be added up to 15% in total.

The average particle diameter D50 of the glass powder is preferably from 0.1 to 100 [mu] m, particularly preferably from 1 to _{50 [} mu] m. When the average particle diameter D ₅₀ of the glass powder is too small, the greater the amount of generation of bubbles during the firing. When many bubbles are contained in the wavelength conversion member, light absorption is caused and the total luminous flux value tends to decrease. In addition, moisture and the like can easily enter the inside, and the chemical durability may be reduced. The preferred porosity is 2% by volume or less, particularly 1% by volume or less. On the other hand, when the average particle diameter D ₅₀ is too large, the inorganic phosphor powder is less likely to be uniformly dispersed in the wavelength conversion member, as a result, total light flux value of the wavelength conversion member tends to decrease.

The wavelength conversion member of the present invention is characterized by having a heterogeneous layer having a composition different from that of the glass powder at the grain boundary of the glass powder. Heterogeneous layer, for _{example, SiO 2, Al 2 O 3} , Y 2 O 3, P 2 O 5, SnO, B 2 O 3, TeO 2, Bi 2 O 3, La 2 O 3, TiO 2, ZnO, ZrO It is preferably made of an amorphous material containing any one or more of ₂ . If the heterogeneous layer contains crystals, the excitation light is absorbed by the crystals and the total luminous flux value may be reduced.

  In order to obtain the wavelength conversion member of the present invention, it is preferable to use a glass powder having a heterogeneous layer on the surface as a raw material and sinter the mixed powder containing the glass powder and the inorganic phosphor powder.

  As a method for producing a glass powder having a heterogeneous layer on the surface, a method of coating the surface of the glass powder by a sol-gel method or a sputtering method (coating method); immersing the glass powder in water, acid or alkali, Method of eluting a part of glass component (elution method); Method of pulverizing glass powder with high energy pulverizer such as jet mill, planetary ball mill, etc., and modifying glass surface by mechanochemical effect (mechanochemical method); different Examples thereof include a method (firing method) of pulverizing after mixing with glass powder having a composition and firing.

  The thickness of the heterogeneous layer is preferably 0.001 to 5 μm, 0.001 to 3 μm, and particularly preferably 0.01 to 2 μm. If the thickness of the heterogeneous layer is too small, it is difficult to obtain the effect of scattering the excitation light. On the other hand, if the thickness of the heterogeneous layer is too large, the scattering loss increases and the total luminous flux value tends to decrease.

  The difference in refractive index between the glass powder and the extraneous layer is preferably 0.001 to 0.5, particularly preferably 0.001 to 0.4. If the refractive index difference between the glass powder and the foreign layer is too small, it is difficult to obtain the effect of scattering the excitation light. On the other hand, if the refractive index difference between the glass powder and the foreign layer is too large, the scattering loss tends to increase and the total luminous flux value tends to decrease.

  Examples of the inorganic phosphor powder include those that emit fluorescence having a wavelength longer than the wavelength of the excitation light when the excitation light in the ultraviolet region or visible region is incident.

  The inorganic phosphor powder usable in the present invention is not particularly limited as long as it is generally available on the market. Examples thereof include garnets such as YAG, and other oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, halophosphates, and the like.

  Among the inorganic phosphor powders, those having 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), yellow (wavelength 540) ˜595 nm) and red (wavelength of 600 to 700 nm) are preferably used.

Examples of inorganic phosphor powder that emits blue light when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 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 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.

Examples of inorganic phosphor powders 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⁺ , 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.

Examples of inorganic phosphor powder that emits yellow fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light having a wavelength of 300 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.

As an inorganic phosphor powder that emits yellow fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm, 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 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.

Examples of inorganic phosphor powders that emit red fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm include 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.

  For example, when an inorganic phosphor powder that emits a complementary color fluorescence to the hue of the excitation light when incident excitation light consisting of visible light is incident, white light can be easily obtained by mixing the transmitted excitation light and fluorescence. A white LED can be manufactured. In particular, it is preferable that excitation light composed of visible light is light having a central wavelength of 430 to 490 nm and fluorescence is light having a central wavelength of 530 to 590 nm because white light can be easily obtained.

  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 powder used as the glass matrix of the wavelength conversion member usually has a refractive index (nd) of about 1.5 to 2.0, whereas the inorganic phosphor powder is about 1.5 to 2.4. Has a wide refractive index. There are various possibilities for combining the glass powder and the inorganic phosphor powder, but particularly when the difference in refractive index between the glass powder and the inorganic phosphor powder is small, scattering at the interface between the two is reduced. As a result, the straight component of the excitation light increases, and the diffusion characteristics are likely to deteriorate. Therefore, it can be said that the wavelength conversion member of the present invention is particularly effective when the difference in refractive index between the glass powder and the inorganic phosphor powder is small (for example, less than 0.05).

  The content of the inorganic phosphor powder in the wavelength conversion member is preferably 1 to 30% by mass, particularly preferably 2 to 20% by mass. When the content of the inorganic phosphor powder is too small, the total luminous flux value becomes insufficient, and it becomes difficult to obtain white light. On the other hand, when there is too much content of inorganic fluorescent substance powder, excitation light is not fully irradiated to the whole inorganic fluorescent substance powder, and there exists a tendency for a total luminous flux value to fall. In addition, pores are easily generated, and it is difficult to obtain a dense structure.

  The wavelength conversion member of the present invention may contain a ceramic powder having translucency such as low temperature type quartz, low temperature type cristobalite, corundum, garnet, tetragonal zirconia, garnite, cordierite and the like. When the wavelength conversion member contains these ceramic powders, the effect of scattering excitation light is further increased, and a wavelength conversion member having excellent diffusion characteristics can be easily obtained. In order to enhance the scattering effect of the excitation light, it is preferable to combine the glass powder and the ceramic powder so that the difference in refractive index is large. Specifically, the difference in refractive index between glass and ceramic powder is preferably 0.05 or more, particularly preferably 0.1 or more.

The average particle diameter _{D 50} of the ceramic powder is 0.1 to 30 [mu] m, it is particularly preferably 0.2 to 5 .mu.m. When the average particle diameter D ₅₀ of the ceramic powder is too small, the effect of scattering the excitation light is hardly obtained. On the other hand, when the average particle diameter D ₅₀ of the ceramic powder is too large, total light flux value scattering loss becomes large tends to decrease.

  The content of the ceramic powder in the wavelength conversion member is preferably 0.1 to 10% by mass, particularly 1 to 8% by mass. If the content of the ceramic powder is too small, it is difficult to obtain the above effect. On the other hand, if the content of the ceramic powder is too large, the scattering loss increases and the total luminous flux value tends to decrease.

  The wavelength conversion member of the present invention has a parallel ray (linear) transmittance measured according to JIS K7105 of 10% or less, particularly preferably 7% or less, and a haze of 80% or more, particularly 85% or more. It is preferable. If the parallel light transmittance is too large or the haze is too small, the straight component of the excitation light tends to be too large and the light diffusion property tends to be inferior. Moreover, it becomes difficult to obtain a desired total luminous flux value.

  The wavelength conversion member of the present invention is formed into a sintered body by pre-molding a mixed powder containing, for example, an inorganic phosphor powder and a glass powder having a heterogeneous layer formed on the surface by the method described above, and firing at a predetermined temperature. Thereafter, it can be produced by performing processing by grinding, polishing, repressing or the like, if necessary.

  The preforming method is not particularly limited, and a press molding method, an injection molding method, a sheet molding method, an extrusion molding method, or the like can be employed.

  The firing temperature of the mixed powder of glass powder and inorganic phosphor powder is preferably not less than the softening point of the glass powder, particularly not less than the softening point + 50 ° C. If the firing temperature is too low, pores remain and the total luminous flux value tends to decrease. On the other hand, although an upper limit is not specifically limited, It is preferable that it is below the softening point of glass powder +100 degreeC. If the firing temperature is too high, the reaction between the glass powder and the inorganic phosphor powder proceeds, and the inorganic phosphor powder partially disappears and the total luminous flux value tends to decrease.

  The wavelength conversion member of the present invention can be used as a light emitting device by combining with a light source such as an LED chip that is an excitation light source. The wavelength conversion member of the present invention may be directly adhered on the light source, or may be adhered on a box surrounding the light source. It is also possible to provide a surface emitting device in which a plurality of light sources are installed below the plate-like wavelength conversion member.

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

  Tables 1-3 show Examples (No. 1-4, 6-9, 11-14) and Comparative Examples (No. 5, 10, 15).

First, raw material powders were weighed and mixed so as to have the glass compositions shown in Tables 1 to 3, and the mixture was melted at 900 to 1400 ° C. for 1 hour in a platinum crucible 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.

  Next, the inorganic phosphor powder and ceramic powder shown in Tables 1 to 3 were mixed with the glass powder, and pressure-molded using a mold to prepare a button-shaped preform having a diameter of 1 cm. This preform was fired at the firing temperatures shown in Tables 1 to 3 to obtain sintered bodies. Sample No. About the glass powder of 1-4, 6-9, and 11-14, before mixing with inorganic fluorescent substance powder and ceramic powder, the heterogeneous layer was formed in the surface by the following method.

Sol-gel method: Glass powder was dispersed in a solution obtained by mixing ethanol, water and ammonia in Si (OC ₂ H ₅ ) ₄ , LiOCH ₃ and Ca (OC ₂ H ₅ ) ₂ which are metal alkoxides, and heated. .

  Elution method: Glass powder was immersed in 50 ml of diluted hydrochloric acid having a concentration of 0.02 mol% maintained at 50 ° C. for 1 hour.

  The sintered body was polished and processed into a diameter of 8 mm and a thickness of 0.3 mm to obtain a wavelength conversion member. With respect to the obtained wavelength conversion member, the thickness and composition of the heterogeneous layer, the refractive index of the glass powder and the heterogeneous layer, the equilibrium light transmittance, the haze, the diffusion characteristics, and the total luminous flux value were measured. The results are shown in Tables 1-3.

  The thickness and composition of the heterogeneous layer were analyzed with a scanning electron microscope (S-4300SE, manufactured by Hitachi High-Technologies Corporation) equipped with EDX.

  The refractive index was shown by the measured value at the d line (wavelength: 587.6 nm) of a helium lamp using a refractometer (KPR-200 manufactured by Kalnew). In addition, the refractive index of glass powder was calculated | required from the glass before grinding | pulverization, and the refractive index of the heterogeneous layer was calculated | required using the glass produced based on the composition obtained by analysis.

  The parallel light transmittance and haze were measured according to JIS K7105.

  Diffusion characteristics are determined by irradiating a wavelength conversion member with a blue LED and visually observing transmitted light from angles of 0 ° and 60 ° with respect to the optical axis. When the degree deviation was recognized, it was evaluated as “×”.

  The total luminous flux value of the wavelength conversion member was measured as follows. In the calibrated integrating sphere, the wavelength conversion member is excited by a blue LED that is lit at a current of 200 mA, the emitted light is taken into a small spectroscope (USB-4000 manufactured by Ocean Optics) through an optical fiber, and an emission spectrum (on the control PC) Energy distribution curve). The total luminous flux value was calculated from the obtained emission spectrum.

  As is apparent from Tables 1 to 3, sample No. The wavelength conversion members 1 to 4, 6 to 9 and 11 to 14 have a small parallel light transmittance of 6.5% or less and a high haze of 84.4% or more. The value was as high as 15 lm or more. On the other hand, sample No. which is a comparative example. The wavelength conversion members 5, 10 and 15 have a high parallel light transmittance of 14.0% or more and a low haze of 77.8% or less, so they have inferior diffusion characteristics and a total luminous flux value of 13 lm or less. It was.

Claims (7)

A wavelength conversion member formed of a sintered body of a mixed powder containing glass powder and an inorganic phosphor powder, the grain boundary of the glass powder, have a heterogeneous layer of different composition than the glass powder, glass powder and heterogeneity wavelength conversion member refractive index difference layers, characterized in 0.001 der Rukoto.   The wavelength conversion member according to claim 1, wherein the thickness of the heterogeneous layer is 0.001 to 5 μm. The wavelength conversion member according to claim 1 or 2 , wherein a glass powder having a heterogeneous layer on the surface is used as a raw material. The wavelength conversion member according to any one of claims 1 to 3 , wherein the parallel light transmittance measured in accordance with JIS K7105 is 10% or less and the haze is 80% or more. The wavelength conversion member according to any one of claims 1 to 4 , comprising 0.1 to 10% by mass of ceramic powder. Inorganic phosphor powder, oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, any claim 1-5, characterized in that it consists aluminate chloride or halophosphate chloride The wavelength conversion member according to any one of the above. Wavelength converting member according to any one of claims 1 to 6, and the light emitting device characterized by including a light source for irradiating excitation light wavelength conversion member.