JP2013197325A - Wavelength conversion member and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength conversion member in which phosphor powder is dispersed in a glass matrix and which is capable of emitting a homogeneous light having a great whole luminous value while maintaining a desired chromaticity range.SOLUTION: A wavelength conversion member in which phosphor powder is dispersed in a glass matrix, includes glass filler powder having a refraction index different from that of the glass matrix.

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 (light emitting diode).

  In recent years, 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 used as backlights for mobile phones and digital cameras. In addition, as a next-generation light source that replaces incandescent lamps and fluorescent lamps, application to lighting applications is also progressing.

  The white LED is composed of, for example, an LED that emits blue or ultraviolet excitation light, and a wavelength conversion member in which phosphor powder is dispersed in a matrix such as a resin. The phosphor powder receives excitation light from the LED and emits light (fluorescence) having a wavelength different from that of the excitation light. On the other hand, some of the excitation light from the LED 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 phosphor powder in the resin matrix, there is a problem that the resin matrix is discolored by heat from the LED and the luminance is lowered when used for a long time. In addition, when a resin containing phosphor powder is applied on the LED, it is difficult to adjust the thickness uniformly, and there is a problem that chromaticity variations are likely to occur.

  In order to solve these problems, a method of dispersing phosphor powder in a glass matrix has been proposed (see, for example, Patent Documents 1 and 2). According to this method, the heat resistance and weather resistance of the wavelength conversion member can be improved. Specifically, even when exposed to a 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., humidity 85% for 2000 hours), a white LED The light emission characteristics of the material hardly change, and even when exposed to ultraviolet rays of sunlight for a long time, there is almost no coloring or deterioration. Furthermore, since it is excellent in workability, it is possible to suppress chromaticity variation due to thickness non-uniformity.

JP 2005-11933 A JP 2003-258308 A

  A wavelength conversion member obtained by dispersing phosphor powder in a glass matrix has a problem that LED excitation light travels straight without being sufficiently scattered inside the wavelength conversion member. In particular, when the difference in refractive index between the glass matrix and the phosphor powder is small, the tendency is remarkable because light scattering at the interface between the two decreases. If the excitation light is not sufficiently diffused and the linear component increases, the light emitted from the light emitting device is not homogeneous, and there is a difference in chromaticity between the range close to the optical axis of the excitation light source and the range away from the optical axis. Tend. Further, since the frequency with which the excitation light strikes the phosphor powder decreases, the fluorescence intensity tends to decrease. Note that when the fluorescence intensity decreases, the total luminous flux value also decreases.

  Increasing the phosphor powder content in the wavelength conversion member increases the amount of light scattering at the interface between the glass matrix and the phosphor powder as a whole, but the chromaticity is deviated from the desired range. The problem will occur.

  In view of the above problems, the present invention is a wavelength conversion member in which phosphor powder is dispersed in a glass matrix, and is homogeneous and fluorescent while maintaining a desired chromaticity range when used in a light emitting device. It aims at providing the wavelength conversion member which can irradiate light with high intensity | strength.

  The present invention relates to a wavelength conversion member in which a phosphor powder is dispersed in a glass matrix, the glass conversion material comprising a glass filler powder having a refractive index different from that of the glass matrix.

  As described above, in the wavelength conversion member in which the phosphor powder is dispersed in the glass matrix, if there are many linear components of the excitation light from the LED, the irradiation light from the light emitting device is not homogeneous, and the chromaticity depends on the irradiation angle. There will be a difference. Therefore, by dispersing glass filler powder having a refractive index different from that of the glass matrix as a light diffusing agent in the glass matrix, the light scattering property (for example, the scattering property of the excitation light component) is enhanced by the difference in the refractive index. As a result, it is possible to obtain a wavelength conversion member capable of irradiating light with uniform and high fluorescence intensity.

  It is possible to increase the light scattering property by dispersing ceramic filler powder (for example, alumina, silica, etc.) in the glass matrix. In this case, however, the ceramic filler powder itself tends to cause light absorption. is there. In addition, a heterogeneous layer and voids are formed at the interface between the glass matrix and the ceramic filler powder, and due to these, scattering loss due to excessive scattering occurs, and the fluorescence intensity tends to decrease. On the other hand, in the wavelength conversion member of the present invention, since the matrix and the filler powder are both made of glass, a heterogeneous layer or void is unlikely to occur at the interface, and a decrease in fluorescence intensity due to light absorption or scattering loss can be suppressed.

  Secondly, the wavelength conversion member of the present invention preferably has a refractive index difference between the glass matrix and the glass filler powder of 0.001 to 1.

  According to the said structure, excitation light is easily scattered by glass filler powder, and it becomes easy to obtain the wavelength conversion member which can irradiate light with uniform and high fluorescence intensity.

  Third, the wavelength conversion member of the present invention preferably has a glass filler powder whose softening point is 30 ° C. or higher higher than the softening point of the glass matrix.

  According to the said structure, it can suppress that a glass filler powder softens and flows and the light diffusibility falls by the heat processing at the time of wavelength conversion member preparation.

Fourthly, in the wavelength conversion member of the present invention, the glass matrix is SnO—P ₂ O ₅ glass, SiO ₂ —B ₂ O ₃ —RO (R is Mg, Ca, Sr or Ba) glass, SiO ₂ —. _{B 2 O 3 -R '2 O} (R' is Li, Na or Ka) is preferably made of glass or _{SiO 2 -B 2 O 3 -RO-} R '2 O -based glass.

Since SnO—P ₂ O ₅ based glass has a relatively high refractive index, it is easy to increase the refractive index difference between the glass matrix and the glass filler powder. In addition, since the difference in refractive index between the glass matrix and the phosphor is small, the excitation light is not sufficiently diffused and the straight component tends to increase. By containing a glass filler having a small refractive index, it becomes easy to improve the light diffusibility, and it becomes easy to obtain a wavelength conversion member capable of irradiating light with a uniform and high fluorescence intensity.

  Fifth, the wavelength conversion member of the present invention is preferably made of a sintered body of a mixed powder containing a glass powder, a glass filler powder, and a phosphor powder as a raw material for the glass matrix.

  According to the said structure, the wavelength conversion member in which the glass filler powder and fluorescent substance powder were disperse | distributed uniformly in a glass matrix can be obtained easily.

  Sixth, the wavelength conversion member of the present invention preferably has a parallel light transmittance of 20% or less and a haze of 70% or more as measured in accordance with JIS K7105.

  A wavelength conversion member that satisfies the parameters has excellent light diffusibility, and it is easy to obtain light that is homogeneous and has high fluorescence intensity.

  Seventh, in the wavelength conversion member of the present invention, the phosphor powder is selected from oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, and halophosphates. It is preferable to consist of at least one kind.

  Eighth, the wavelength conversion member of the present invention preferably contains 1 to 30% by volume of phosphor powder and 0.05 to 50% by volume of glass filler powder.

  Ninthly, 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 of a phosphor powder.

  Since the wavelength conversion member of the present invention is formed by dispersing glass filler powder having a refractive index different from that of the glass matrix as a light diffusing agent in the glass matrix, the light scattering property is increased due to the difference in refractive index. As a result, uniform and high fluorescence intensity can be obtained.

  The wavelength conversion member of the present invention is formed by dispersing phosphor powder in a glass matrix, and contains a glass filler powder having a refractive index different from that of the glass matrix.

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

Examples of the glass that can be used for the glass matrix include SiO ₂ —B ₂ O ₃ —RO (R is Mg, Ca, Sr, or Ba) -based glass, SiO ₂ —B ₂ O ₃ —R ′ ₂ O (R ′ is Li , Na or Ka) based glass, SiO ₂ —B ₂ O ₃ —RO—R ′ ₂ O (R is Mg, Ca, Sr or Ba, R ′ is Li, Na or Ka) based glass, SnO—P ₂ O Examples thereof include ₅ glass, TeO ₂ glass, Bi ₂ O ₃ glass, and the like.

The SiO ₂ -B ₂ O ₃ -RO 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 0~45%, Li 2 O 0~20%, Na 2 O 0~20%, K 2 O 0~20%, Li 2 O + Na 2 O + K 2 O 0~ Those containing 20%, Al ₂ O ₃ 0-20% and ZnO 0-20% are preferred. The reason for limiting the glass composition in this way will be described below.

SiO ₂ is a component that forms a glass network. 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, comprising a 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. Moreover, there is an effect of improving the light diffusibility by splitting the glass. 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, and also has the effect of promoting phase separation. 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. In addition, the phase separation tendency increases, and the phase separation state tends to fluctuate greatly even with a small change in the heat treatment temperature. As a result, the light diffusibility tends to vary.

  CaO is a component that improves the meltability by lowering the melting temperature, and also has the effect of promoting phase separation. The CaO content is preferably 0 to 30%, particularly preferably 3 to 20%. When there is too much content of CaO, chemical durability will fall or a phase separation tendency will become large easily.

  SrO is a component that improves the meltability by lowering the melting temperature, and also has the effect of promoting phase separation. 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 or the phase separation tendency tends to increase.

  BaO is a component that improves the meltability by lowering the melting temperature, and has the effect of promoting phase separation. Moreover, it is also a component which suppresses reaction with fluorescent substance powder. The BaO content is preferably 0 to 40%, particularly preferably 5 to 30%. When there is too much content of BaO, chemical durability will fall or a phase separation tendency will become large easily.

  The total amount of MgO, CaO, SrO, and BaO is preferably adjusted appropriately in the range of 0 to 45%, particularly 5 to 40% in consideration of the characteristics of the above components.

Li ₂ O is a component for reducing the yield point and significantly promoting phase separation. The content of Li ₂ O is preferably 0 to 20%, 0.1 to 10%, 1 to 7%, particularly 2 to 5%. The content of Li 2 _O is too large, or reduced chemical durability, phase separation tendency tends to increase.

Na ₂ O is a component for lowering the yield point and promoting phase separation. The content of Na ₂ O is preferably 0 to 20%, 0 to 10%, particularly preferably 0 to 2%. When the content of Na 2 _O is too large, or reduced chemical durability, phase separation tendency tends to increase.

K ₂ O is a component for lowering the yield point and promoting phase separation. The content of K ₂ O is preferably 0 to 20%, 0 to 15%, 0 to 5%, particularly preferably 0 to 2%. When the content of K 2 _O is too large, or reduced chemical durability, phase separation tendency tends to increase.

The total amount of Li ₂ O, Na ₂ O and K ₂ O is in the range of 0 to 20%, 0.1 to 15%, 1 to 10%, particularly 2 to 8% in consideration of the characteristics of the above components. It is preferable to adjust as appropriate.

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

  ZnO is a component that significantly promotes phase separation and is a component that improves the meltability by lowering the melting temperature. The content of ZnO is preferably 0 to 20%, particularly preferably 1 to 18%. When there is too much content of ZnO, chemical durability will fall or a phase separation tendency will become large easily.

In addition to the above components, 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 are used to improve chemical durability. O ₃ , SnO ₂ , Bi ₂ O ₃ or ZrO ₂ may be added up to 15% each.

The _SnO-P 2 _{O 5} based glass, 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 network 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 will precipitate in glass, and there exists a tendency for the transmittance | permeability to fall, As a result, the fluorescence intensity of a wavelength conversion member tends to fall. 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 is increased, there is a tendency that weather resistance is remarkably lowered.

B ₂ O ₃ is a component for improving weather resistance and a component for promoting phase separation. It is also a component that stabilizes 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 is 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. Besides, 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 , Bi ₂ O ₃ , TeO ₂ or La ₂ O ₃ may be added up to 15% each.

  The wavelength conversion member of the present invention is not particularly limited as long as the phosphor powder and the glass filler powder are dispersed in the glass matrix, but the glass powder, the glass filler powder and the phosphor powder which are the raw materials for the glass matrix are used. It is preferable that it is made of a sintered body of a mixed powder containing, since the phosphor powder and the glass filler powder can be easily and uniformly dispersed in the glass matrix.

In this case, the average particle diameter _{D 50} of the glass powder as a raw material of the glass matrix is 0.1 to 100 [mu] m, it is particularly preferably 1 to 50 [mu] m. If the average of the glass powder the particle diameter D ₅₀ is too small, an increasing number generation amount of air bubbles during the firing, air bubbles are likely to remain in the wavelength conversion member. If the bubble is contained in the wavelength conversion member, light scattering becomes excessive, and the fluorescence intensity tends to decrease due to scattering loss. In addition, moisture and the like can easily enter the member, and chemical durability may be reduced. The porosity of the wavelength conversion member is preferably 5% or less, 3% or less, and particularly preferably 1% or less. When the average particle diameter D ₅₀ of the glass powder is too large, the phosphor powder is less likely to be uniformly dispersed in the wavelength conversion member, as a result, the fluorescence intensity of the wavelength conversion member is or, or cause variation in chromaticity decreased Tend.

  As the glass filler powder, a glass matrix having a refractive index (nd) different from that of the glass matrix is used. The difference in refractive index between the glass matrix and the glass filler powder is preferably 0.001 to 1, particularly 0.005 to 0.5. When the difference in refractive index between the glass matrix and the glass filler powder is too small, it becomes difficult to obtain sufficient light scattering properties. On the other hand, if the difference in refractive index between the glass matrix and the glass filler powder is too large, the scattering loss tends to increase and the fluorescence intensity tends to decrease.

The average particle diameter _{D 50} of the glass filler powder 0.1～120Myuemu, it is particularly preferably 0.2 to 30. When the average particle diameter D ₅₀ of the glass filler powder is too small, sufficient light scattering properties is difficult to obtain. On the other hand, when the average particle diameter D ₅₀ is too large, the glass filler powder less likely to be uniformly dispersed in the wavelength conversion member, as a result, tend to fluorescence intensity of the wavelength conversion member is or, or cause variation in chromaticity decreased There is.

  The glass constituting the glass filler powder is not particularly limited and can be used as long as it has a refractive index different from that of the glass matrix, and may be a multicomponent glass or a single component glass such as silica glass. Also good. In addition, the softening point of the glass filler powder is 30 ° C. higher than the softening point of the glass matrix from the viewpoint of suppressing a decrease in light diffusibility due to the softening and flow of the glass filler powder in the heat treatment step during the wavelength conversion member preparation. As described above, it is preferably 50 ° C. or higher, particularly 100 ° C. or higher.

  The shape of the glass filler powder is not particularly limited, and examples thereof include a spherical shape, a crushed shape, a hollow shape, a rod shape, and a fiber shape.

  The glass filler powder content in the wavelength conversion member is preferably 0.05 to 50% by volume, particularly preferably 0.1 to 45% by volume. If the content of the glass filler powder is too small, it is difficult to obtain sufficient light scattering properties. On the other hand, when the content of the glass filler powder is too large, the scattering loss tends to increase and the fluorescence intensity tends to decrease. In addition, when the refractive index difference between the phosphor powder and the glass matrix is relatively large, light scattering tends to occur from the beginning, so that the scattering loss tends to increase due to the addition of the glass filler powder. Therefore, it is preferable to appropriately select the content of the glass filler powder in consideration of the refractive index difference between the phosphor powder and the glass matrix.

  Examples of the phosphor powder include those that emit fluorescence having a wavelength longer than the wavelength of the excitation light when ultraviolet or visible excitation light is incident. For example, when excitation light consisting of visible light is incident, if phosphor powder that emits a complementary color fluorescence with respect to the hue of the excitation light is used, 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 is easily obtained.

  The phosphor powder that can be used in the present invention is not particularly limited as long as it is generally available on the market. Examples thereof include inorganic phosphor powders composed of at least one selected from oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, and halophosphates. In addition, a phosphor made of an organic material may be used.

  Among the 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 to 540) It is preferable to use one that emits light at a wavelength of 595 nm and red (wavelength 600 to 700 nm).

Examples of the 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, Ba) ₃ MgSi ₂ O ₈ : Eu ²⁺ .

The phosphor powder that emits green fluorescence when irradiated with ultraviolet to near-ultraviolet excitation light of wavelength ^{_{300~440nm, SrAl 2 O 4: Eu}} 2+ and the like.

Examples of the phosphor powder that emits green fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm include SrGa ₂ S ₄ : Eu ²⁺ .

Examples of the 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+ and the} like.

As phosphor powders that emit 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⁺ , SrBaSiO ₄ : Eu ²⁺ , La ₃ Si ₆ N ₁₁ : Ce ^{3+ and the} like.

Examples of the 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⁺ .

Examples of the phosphor powder that emits red fluorescence when irradiated with blue excitation light having a wavelength of 440 to 480 nm include (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ .

  A plurality of 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 irradiating excitation light in the ultraviolet region, phosphor powders that emit blue, green, yellow, and red fluorescence may be mixed and used.

  The glass used as the glass matrix of the wavelength conversion member usually has a refractive index of about 1.5 to 2.0, whereas the phosphor powder has a wide refractive index of about 1.5 to 2.4. . The combination of glass and phosphor powder has various possibilities, but especially when the refractive index difference between the glass and phosphor powder is small, scattering at the interface between the two becomes small. As a result, the straight component of the excitation light increases, and the light diffusibility tends to decrease. Therefore, it can be said that the wavelength conversion member of the present invention is particularly easy to obtain the above-described effect when the difference in refractive index between the glass matrix and the phosphor powder is small (for example, less than 0.05).

  The content of the phosphor powder in the wavelength conversion member is preferably 1 to 30% by volume, particularly 2 to 20% by volume. If the content of the phosphor powder is too small, the amount of light emission becomes insufficient, making it difficult to obtain desired white light. On the other hand, even if there is too much content of phosphor powder, it becomes difficult to obtain desired white light. Further, the excitation light is not sufficiently applied to the entire phosphor powder, and the fluorescence intensity may be reduced. Furthermore, pores are easily generated, and it is difficult to obtain a dense structure.

  The wavelength conversion member of the present invention preferably has a parallel ray (linear) transmittance measured in accordance with JIS K7105 of 20% or less, particularly 10% or less. Moreover, it is preferable that the haze similarly measured based on JIS K7105 is 70% or more, especially 75% or more. If the parallel light transmittance is too large or the haze is too small, the linear component of the excitation light tends to increase so that the fluorescence intensity decreases and color variation tends to occur.

  The wavelength conversion member of the present invention is formed into a sintered body by pre-molding a mixed powder containing, for example, glass powder, phosphor powder, and glass filler powder, which is a raw material of the glass matrix, and firing it at a predetermined temperature, and then required. Accordingly, it can be produced by processing by grinding, polishing, repressing or the like.

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

  The firing temperature is preferably not less than the softening point of the glass powder used as a raw material for the glass matrix, particularly not less than the softening point + 50 ° C. When the firing temperature is lower than the softening point of the glass powder, pores remain and the fluorescence intensity tends to decrease. On the other hand, the upper limit of the firing temperature is not particularly limited, but if it is too high, the reaction between the glass powder and the phosphor powder proceeds, and the phosphor powder tends to be partially deactivated to reduce the total high speed value. Therefore, it is preferable that a calcination temperature is the softening point of glass powder +100 degrees C or less.

  The wavelength conversion member of the present invention can be used as a light emitting device by combining the wavelength conversion member with a light source that emits excitation light of phosphor powder. As the light source, a semiconductor light emitting element such as an LED or an LD (laser diode) can be used.

  The wavelength conversion member may be directly adhered on the semiconductor light emitting element or may be adhered on a box surrounding the semiconductor light emitting element. It is also possible to provide a surface light emitting device in which a plurality of semiconductor light emitting elements 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 1-4 show Examples (No. 1-4, 6, 7, 9, 10, 12) and Comparative Examples (No. 5, 8, 11, 13).

First, glass raw materials were weighed and mixed so as to have the glass composition shown in the table, and this mixture was melted in a platinum crucible at 900 to 1400 ° C. for 1 hour to be vitrified. Molding the molten glass into a film, and the obtained film-like glass was pulverized by a ball mill and then classified through a sieve of 325 mesh, the average particle diameter D ₅₀ was obtained glass powder 30 [mu] m.

  Next, the phosphor powder and filler powder shown in the table 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 temperature shown in the table to obtain a sintered body. The sintered body was subjected to a polishing treatment and processed into a diameter of 8 mm and a thickness of 0.5 mm to obtain a wavelength conversion member. The obtained wavelength conversion member was measured for parallel light transmittance, haze, and fluorescence intensity. The results are shown in Tables 1-4.

  In addition, the refractive index of the glass matrix and filler powder was shown by the measured value in d line | wire (wavelength: 587.6 nm) of a helium lamp using the refractometer (KPR-200 by a Calnew company). Moreover, the softening point of the glass matrix and filler powder was measured by a differential thermal analysis (DTA) apparatus.

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

  The fluorescence intensity was measured as follows. In a calibrated integrating sphere, a blue LED lit at a current of 200 mA is irradiated onto a wavelength conversion member, and the obtained light is taken into a small spectroscope (Ocean Optics USB-4000) through an optical fiber and emitted onto a control PC. A spectrum (energy distribution curve) was obtained. The fluorescence intensity was calculated from the obtained emission spectrum.

Table 1 shows an example in which Y ₃ (Al, Gd) ₅ O ₁₂ : Ce ²⁺ (YAG) is used as the phosphor powder. As is clear from Table 1, sample No. In the wavelength conversion members 1 to 4, the parallel light transmittance was as low as 10.1% or less and the haze was as large as 82.3% or more, so the fluorescence intensity was high. Here, it can be seen that the greater the refractive index difference between the glass matrix and the filler powder, and the greater the filler powder content, the higher the fluorescence intensity. On the other hand, sample No. which is a comparative example. Since the wavelength converting member 5 contained no glass filler powder, the parallel light transmittance was as high as 19.3% and the haze was as large as 69.7%, so that the fluorescence intensity was low.

The same tendency as above was also observed when SrBaSiO ₄ : Eu ²⁺ was used as the phosphor powder (Nos. 6 to 8). When (Ca, Sr) ₂ Si ₅ N ₈ : Eu ²⁺ is used as the phosphor powder (No. 9 to 13), the fluorescence intensity increases up to a glass filler powder content of 5%. Thereafter, it can be seen that the fluorescence intensity decreases as the content increases. It can be seen that when the content of the glass filler powder is 10% or more, light scattering becomes excessive, and the fluorescence intensity is reduced due to scattering loss. On the other hand, since the wavelength conversion member of sample No. 13 as a comparative example did not contain glass filler powder, the fluorescence intensity was low.

  Table 4 shows the results of comparing the characteristics of the glass filler powder and the alumina powder having the same refractive index. As is apparent from Table 4, No. using glass filler powder. No. 14 wavelength conversion member is No. 14 using alumina powder. Compared with 15 wavelength conversion members, the parallel light transmittance was low and the haze was large, so the fluorescence intensity was high. This is because the alumina powder itself caused light absorption.

Claims (9)

  A wavelength conversion member formed by dispersing phosphor powder in a glass matrix, comprising a glass filler powder having a refractive index different from that of the glass matrix.   The wavelength conversion member according to claim 1 or 2, wherein a difference in refractive index between the glass matrix and the glass filler powder is 0.001 to 1.   The wavelength conversion member according to any one of claims 1 to 3, wherein the softening point of the glass filler powder is 30 ° C or more higher than the softening point of the glass matrix. The glass matrix is SnO—P ₂ O ₅ based glass, SiO ₂ —B ₂ O ₃ —RO (R is Mg, Ca, Sr or Ba) based glass, SiO ₂ —B ₂ O ₃ —R ′ ₂ O (R ′ _2. The wavelength conversion member according to claim 1, comprising Li, Na, or Ka) glass or SiO ₂ —B ₂ O ₃ —RO—R ′ ₂ O glass.   The wavelength conversion member according to any one of claims 1 to 4, wherein the wavelength conversion member comprises a sintered body of a mixed powder containing glass powder, glass filler powder, and phosphor powder as a raw material of the glass matrix.   The wavelength conversion member according to any one of claims 1 to 5, wherein the parallel light transmittance measured in accordance with JIS K7105 is 20% or less and the haze is 70% or more.   The phosphor powder is made of at least one selected from oxides, nitrides, oxynitrides, sulfides, oxysulfides, rare earth sulfides, aluminate chlorides, and halophosphate chlorides. Item 7. The wavelength conversion member according to any one of Items 1 to 6.   The wavelength conversion member according to any one of claims 1 to 7, comprising 1 to 30% by volume of phosphor powder and 0.05 to 50% by volume of glass filler powder.   A light emitting device comprising: the wavelength conversion member according to claim 1; and a light source that irradiates the wavelength conversion member with excitation light of a phosphor powder.