JP2003258308A - Emission color converting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emission color converting member capable of producing a highly reliable, long lifetime white color illumination light source using a blue color LED element, especially a high output blue color LED element. <P>SOLUTION: The emission color converting member for converting a part of blue color light emitted from a blue color light source into yellow light and synthesizing it with the remaining blue color light to generate white color light in which an inorganic phosphor is dispersed into glass having a melting point higher than 500°C. An oxide phosphor, e.g. a Y<SB>3</SB>Al<SB>5</SB>O<SB>12</SB>based phosphor, is suitably employed as the inorganic phosphor. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting color conversion member for converting blue light from a blue light source, particularly a blue light emitting diode (LED) element, into white light.

[0002]

2. Description of the Related Art In recent years, white LEDs have attracted attention as a highly efficient and highly reliable white illumination light source, and a part thereof has already been used as a micro-power small-sized light source. This kind of LED is
Generally, a blue LED element is covered and molded with a mixture of a yellow phosphor and a transparent resin.

[0003]

However, since blue light has high energy, it tends to deteriorate the resin. Therefore, in the white LED having such a structure, the resin changes color and the color tone changes after long-term use. Also, recently, there is a movement to develop a white illumination light source using a high-power LED element, but in this case, since extremely intense blue light is irradiated to a limited part, deterioration of the resin is remarkable and a change in emission color is caused. It happens in a very short time. Further, since the heat dissipation from the resin-molded element is poor, the temperature easily rises, and there is a problem that the color tone of the emission color shifts to the yellow side as the temperature rises.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a light emitting color conversion member capable of obtaining a white illumination light source with high reliability and long life even if a blue LED element, particularly a high output blue LED element is used.

[0005]

The luminescent color conversion member of the present invention converts a part of blue light emitted from a blue light source into yellow light and combines the remaining blue light with the remaining blue light to obtain white light. A color conversion member, characterized in that an inorganic phosphor is dispersed in glass having a softening point higher than 500 ° C.

The material for a luminescent color conversion member of the present invention converts a part of blue light emitted from a blue light source into yellow light,
It is a material for an emission color conversion member for obtaining white light by combining with the remaining blue light, and is characterized by comprising a mixture of glass powder having a softening point higher than 500 ° C. and inorganic phosphor powder.

Further, the white illumination light source of the present invention has a blue light source and an emission color conversion member, converts a part of the blue light emitted from the blue light source into yellow light, and synthesizes it with the rest of the blue light to obtain a white light. It is a white illumination light source for obtaining light, and is characterized by using a luminescent color conversion member in which an inorganic phosphor is dispersed in glass having a softening point higher than 500 ° C.

[0008]

The luminescent color conversion member of the present invention has a structure in which an inorganic phosphor is dispersed in glass. More specifically, it is composed of a sintered body of glass powder and inorganic phosphor powder.

As the inorganic fluorescent substance, one capable of converting blue light emitted from a blue light source into yellowish light, for example, greenish yellow (emission peak of about 550 nm), is generally available in the market. Can be used. Some inorganic phosphors are composed of sulfides, halophosphates, oxides and the like.
Oxide phosphors are stable even when mixed with glass and heated to high temperatures, but phosphors such as sulfides and halophosphates react with glass due to heating during sintering and cause abnormalities such as foaming and discoloration. Easy to react. The degree becomes more remarkable as the sintering temperature becomes higher. Therefore, it is preferable to use an oxide phosphor as the inorganic phosphor. The most preferable oxide phosphor is (Y, Gd, Ce) ₃ Al ₅ O
Examples thereof include Y ₃ Al ₅ O ₁₂ based phosphors such as ₁₂ .

The glass is limited to those having a softening point above 500 ° C., preferably above 600 ° C. The reason is that glass having a softening point of 500 ° C. or lower reacts with the phosphor to turn the sintered body dark, resulting in a significant decrease in luminous efficiency and no transmission of light. Further, the chemical durability is apt to deteriorate, and in a humid environment, the surface may be deteriorated during use to lower the transmittance and reduce the efficiency.

A glass having a coefficient of thermal expansion of more than 75 × 10 ^-7 / ° C. is not preferable because cracks are likely to occur in the sintered body due to thermal shock due to repeated temperature increase during lighting and temperature decrease during extinction. Therefore, the softening point is 500 ° C or higher (particularly 600 ° C or higher), and the thermal expansion coefficient is 75 × 10 ^-7 / ° C.
The following glass (especially 20 to 70 × 10 ⁻⁷ / ° C.) is preferable.

When PbO or Bi ₂ O ₃ is contained in the glass composition, it reacts with the phosphor to easily lower the brightness of the sintered body, which is not preferable because it lowers the luminous efficiency. Further, it is important not to contain an oxide that causes solarization or a coloring element that hinders transmission of light, and to not include such impurities. For example, in the composition
If O, Fe ₂ O ₃ , CeO ₂ or the like is contained, the glass is discolored by ultraviolet rays, so that the inclusion of these components is not preferable. If it also contains an alkali metal oxide,
It deteriorates the resin used for the bonding and molding of the members and reduces the bonding strength. Therefore, it is preferable that the glass composition does not substantially contain the above components. Specifically, PbO and Bi ₂ O ₃ are each 3% or less, MnO and Fe.
It is desirable to limit each of ₂ O ₃ and CeO _{2 to} 1000 ppm or less and the total amount of alkali metal oxides to 15% or less.

Since the color tone of the sintered body and the reactivity with the phosphor differ depending on the composition system, it is necessary to select the composition of the glass to be used in consideration of various conditions. Further, it is important to determine the addition amount of the phosphor suitable for the glass composition and the thickness of the member. Suitable glass in the present invention B ₂ O ₃ -SiO ₂ -based glass, BaO
-B ₂ O ₃ -SiO ₂ based glass, ZnO-B ₂ O ₃ -Si
Examples thereof include O ₂ glass.

In the luminescent color conversion member of the present invention, it is difficult to obtain practical mechanical strength when the thickness of the member is less than 0.2 mm.
Therefore, for applications requiring mechanical strength, 0.2 mm
It is preferable to have the above thickness. Further, in this case, the content of the inorganic phosphor is preferably 0.01 to 15% by volume. When the phosphor content is less than 0.01% by volume, yellow light is insufficient and white light is difficult to be emitted.
When it exceeds%, the amount of blue light is shielded by the phosphor and the amount of blue light becomes too small, and the light shifts to yellow. In some cases, the yellow light itself is also blocked and the luminous efficiency is significantly reduced. A more desirable phosphor content is 0.05 to 10%, and especially 0.1.
It is from 08 to 8% by volume, and further from 0.1 to 3% by volume.

The luminescent color conversion member of the present invention is molded into various shapes such as a disk-shaped conversion member 10 as shown in FIG. 1 and a cylindrical cap-shaped conversion member 20 as shown in FIG. be able to. In FIG. 1, 11 indicates an inorganic phosphor and 12 indicates glass. Further, as shown in FIG. 3, the emission color conversion member 30 and the support member 4 for supporting the same.
It is also possible to use it as a composite part consisting of 0 and. As the support member, various shapes can be adopted, and for example, a cylindrical shape as shown in FIG. 3 can be used. The support member is made of a different material such as resin, ceramic, or metal. The material may be appropriately selected in consideration of conditions such as mechanical strength and expansion. Moreover, the conversion member may be attached by a method such as fitting or adhesion.

In the luminescent color conversion member of the present invention having the above structure, since the phosphor is dispersed in the glass, a part of the incident blue light is converted into yellow light by the inorganic phosphor,
Further, the remaining blue light is transmitted and scattered. The converted yellow light is combined with the transmitted and scattered blue light to synthesize a spectrum close to white light, whereby blue light is converted to white light.

When the scattering of the incident light is small, the obtained white light is strong and bright, and when the scattering is large, it is soft.

Further, as the thickness of the member increases, the brightness decreases, and the luminous efficiency decreases. Furthermore, since the absolute amount of the phosphor increases and the amount of yellow light increases, the emission color tends to shift to the yellow side. On the other hand, if the member is thin, the luminous efficiency will be high,
Since the absolute amount of the phosphor decreases and the yellow light decreases, it is easy to shift to the blue side. Therefore, in order to efficiently obtain white light, it is important to adjust the amount of phosphor and the thickness of the member.

Next, a method for producing the luminescent color conversion member of the present invention will be described.

First, glass powder and inorganic phosphor powder having the above characteristics are prepared. If it is desired to increase the scattering of the conversion member obtained here, glass powder having a small particle size may be used, and if it is desired to reduce the scattering, a glass powder having a large particle size may be used. Further, the preferable particle size range of the glass powder is that the maximum particle diameter Dmax is 150 μm or less (particularly 45 to
105 μm), and the average particle diameter D ₅₀ is 2 μm or more (particularly 10 to 20 μm). That is, when the maximum particle diameter of the glass powder exceeds 150 μm, transparent portions formed by coarse glass particles are scattered in the sintered body, and it becomes difficult to scatter light, so that a uniform scatterer cannot be obtained. , White light tends to be bluish. When the average particle diameter D ₅₀ is less than 2 μm, the sintered body excessively scatters light, so that the blue light transmittance is significantly reduced, the luminous efficiency is reduced, and the white light is yellowish. It becomes easy to take on.

Next, the inorganic phosphor powder and the glass powder are mixed to obtain a material for a luminescent color conversion member. The mixing ratio may be adjusted in consideration of the thickness of the member to be manufactured. That is, when the thickness of the member is thin, the proportion of the phosphor powder may be set high, and when it is thick, the proportion may be set low.

Subsequently, a resin binder is added and pressure molding is carried out to prepare a preform having a desired shape.

Then, the preform is fired to remove the resin binder and sintered to obtain a luminescent color conversion member. In the case of a composite part, the obtained conversion member may be attached to a separately prepared support member.

The luminescent color conversion member thus obtained (or the luminescent color conversion composite component to which it is attached) can be used as a white illumination light source by combining it with a blue light source such as a blue LED element.

[0025]

EXAMPLES The present invention will be described below based on examples.

Tables 1 to 3 show glass samples (Samples A to M) used in this example.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

Each sample was prepared as follows. First, silica sand, boric acid, aluminum oxide, bismuth oxide, zinc oxide, calcium carbonate, barium carbonate, lithium carbonate, sodium carbonate, potassium carbonate and red lead were prepared in the proportions shown in the table. Then, this was put into a platinum crucible, melted at 800 to 1500 ° C. for 1 to 3 hours to vitrify, and formed into a film. After crushing the film glass with a ball mill, it is passed through a 150 mesh (JIS) sieve and classified to have a maximum particle size of 105 μm and an average particle size of about 20.
A glass powder sample (normal product) of μm was obtained. For sample H, the maximum particle size is 150μ in addition to the normal particle size product.
m, average particle diameter of about 30 μm, coarse particles and maximum particle diameter of 10
A fine product having a particle size of μm and an average particle size of about 1.8 μm was prepared.

The glass powder sample thus obtained was measured for density, coefficient of thermal expansion and softening point. The results are shown in the table.

The softening point was obtained by further grinding a glass powder sample with a ball mill to obtain a maximum particle diameter of 45 μm and an average particle diameter of 10
A powder sample having a particle size of μm was prepared and determined by DTA.
The density and the coefficient of thermal expansion were determined by the Archimedes method and TMA, respectively, after molding the molten glass into a block-shaped sample and a cylindrical sample for property measurement and annealing.

Tables 4 to 7 show the above-mentioned glass powder samples,
An example of a luminescent color conversion member obtained by sintering an inorganic phosphor powder is shown.

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

[0037]

[Table 7]

Each sample was prepared as follows. First, a phosphor powder was added to and mixed with a glass powder sample at a ratio shown in Tables 4 to 7 to prepare a mixed powder. Further, a small amount of resin binder was added and mixed, and then pressure-molded with a mold to prepare a button-shaped preform having a diameter of 1 cm. As the phosphor, (Y, Gd, Ce) ₃ Al ₅ O ₁₂ (P46-Y3 manufactured by Kasei Optonix Co., Ltd.) was used.

Subsequently, the preform is sintered at a sintering temperature (shown in each table) determined from the softening point of each glass, and the diameter is about 8 mm, the thickness is 0.2 mm, 0.5 mm, and 1.0 mm. ,
It was processed into a disk-shaped sintered body having a size of 1.5 mm or 2.0 mm.

With respect to the obtained sintered body samples, the color tone of the sintered body, the color tone of transmitted light and the strength were visually evaluated. The color tone and intensity of the transmitted light are obtained by evaluating the transmitted light from the sintered body when the blue light of the LED is irradiated from the back of the sintered body. The closer the color tone is to white, the stronger the intensity. The better the luminous efficiency, the better.

[0041]

Since the luminescent color conversion member of the present invention is mainly composed of glass that is chemically stable and has high thermal conductivity, it does not discolor even when exposed to high-power blue light for a long period of time. Since there is little temperature rise, there is no discoloration of white light. Therefore, a highly reliable white illumination light source can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a disc-shaped emission color conversion member.

FIG. 2 is a cross-sectional view showing a cap-shaped emission color conversion member.

FIG. 3 is a cross-sectional view showing a luminescent color conversion composite component using a support member.

[Explanation of symbols]

10, 20, 30 Emission color conversion member 11 Inorganic phosphor 12 glass 40 Support member

Claims (13)

[Claims] 1. A luminescent color conversion member for converting a part of blue light emitted from a blue light source into yellow light and synthesizing it with the remaining blue light to obtain white light, which has a softening point of 500 ° C. or higher. An emission color conversion member, characterized in that an inorganic phosphor is dispersed in high glass. 2. The luminescent color conversion member according to claim 1, wherein the inorganic phosphor is an oxide phosphor. 3. The emission color conversion member according to claim 1, wherein the inorganic phosphor is a Y ₃ Al ₅ O ₁₂ type phosphor. 4. The luminescent color conversion member according to claim 1, wherein the glass has a coefficient of thermal expansion of 75 × 10 ⁻⁷ / ° C. or less. 5. The luminescent color conversion member according to claim 1, wherein the glass does not substantially contain Bi ₂ O ₃ . 6. The glass comprises MnO, Fe ₂ O ₃ , and Ce.
O ₂ is not contained substantially, Claim 1 characterized by the above-mentioned.
4 or 5 emission color conversion member. 7. The content of the inorganic phosphor is 0.0% by volume.
It is 1 to 15%, The luminescent color conversion member of Claim 1 characterized by the above-mentioned. 8. The luminescent color conversion member according to claim 1, wherein a mixed powder of glass powder and inorganic phosphor powder is sintered. 9. A glass powder having a maximum particle diameter Dmax of 1
The luminescent color conversion member according to claim 8, wherein the luminescent color conversion member has an average particle diameter D _{50 of 50} μm or less and 2 μm or more. 10. The emission color conversion member according to claim 1, wherein the blue light source is a blue light emitting diode element. 11. A composite component for emission color conversion, comprising the emission color conversion member according to claim 1 and a support member for supporting the same. 12. A material for an emission color conversion member for converting a part of blue light emitted from a blue light source into yellow light and combining the remaining blue light to obtain white light, which has a softening point of 50.
A material for a luminescent color conversion member comprising a mixture of a glass powder having a temperature higher than 0 ° C. and an inorganic phosphor powder. 13. A blue light source and an emission color conversion member,
It is a white illumination light source that converts a part of blue light emitted from a blue light source into yellow light and synthesizes it with the rest of the blue light to obtain white light. Inorganic phosphor is contained in glass having a softening point higher than 500 ° C. A white illumination light source characterized by using dispersed emission color conversion members.