JPWO2014162893A1 - Light conversion member, method for manufacturing the same, illumination light source, and liquid crystal display device - Google Patents

Abstract

Provided are a light conversion member capable of maintaining the light emission conversion efficiency and a method for manufacturing the same, while maintaining good dispersibility of phosphor particles and not reducing the light transmittance from a light source. A light conversion member made of glass containing dispersed phosphor particles, wherein a heat-resistant filler is further dispersed in the glass, and the heat-resistant filler has a 50% particle diameter D50 and a wavelength of 633 nm. A light conversion member having a relational expression [D50 / n] with a refractive index n of 2 is 20 to 20 and a mixed powder of raw materials is kneaded with a vehicle to obtain a slurry, which is molded, and further fired Manufacturing method.

Description

  The present invention relates to a light conversion member for converting the color of a light source, a method for manufacturing the light conversion member, an illumination light source having the light conversion member, and a liquid crystal display device.

  The white LED is used as a white illumination light source with a minute electric power, and is expected to be applied to illumination applications. In general, the white light of a white LED is light of yellow, green, red, etc., which is a blue light emitted from a blue LED element serving as a light source and a color (wavelength) of a part of the blue light converted by a phosphor. And is obtained by synthesizing

  As a light conversion member for converting the color (wavelength) of light of such a light source, a member in which an inorganic phosphor is dispersed in glass is known (for example, see Patent Document 1). The light conversion member having such a configuration can utilize the high transmittance of glass, and can efficiently release the heat generated from the LED element to the outside of the light conversion member. Moreover, the damage of the light conversion member (especially phosphor) by light and heat is low, and long-term reliability is obtained.

  In addition, light-dispersible particles are present in the glass in which the phosphor is dispersed (see Patent Document 2), or a light-scattering layer having light-scattering particles is present as a separate layer from the glass in which the phosphor is dispersed. (See Patent Document 3), a light conversion member that scatters light from a light source to improve luminous efficiency is also known.

JP 2003-258308 A Japanese Patent No. 4286104 Japanese Patent Application Laid-Open No. 2011-074104

  However, as described in Patent Document 1, when the phosphor is contained only in the glass, the light conversion member itself may be greatly shrunk due to firing when the light conversion member is manufactured. When contraction occurs, the amount of phosphor present varies due to the difference in the degree of contraction between the central portion and the outer peripheral portion in the plane of the light conversion member, and this causes unevenness in light conversion chromaticity within the surface of the light conversion member. Cause. Therefore, when the shrinkage increases, the unevenness of the light conversion chromaticity also increases, and it becomes impossible to obtain light with a uniform color tone.

  Moreover, when it is a light conversion member which has light-scattering particle | grains like patent document 2 and 3, while there is a possibility that conversion efficiency can be improved by earning optical path length by light scattering, on the other hand, transmission of the light from a light source Since the rate decreases and the amount of light flux decreases, the overall light utilization efficiency may not be sufficiently improved.

  Therefore, in view of the above problems, the present invention suppresses shrinkage during the manufacture of the light conversion member to maintain good dispersibility of the phosphor particles, suppresses unevenness in chromaticity, and further suppresses the light from the light source. An object of the present invention is to provide a light conversion member that can maintain transmittance.

  As a result of intensive studies by the present inventors, it has been found that by using a heat-resistant filler having predetermined characteristics, it is possible to suppress shrinkage during firing of the light conversion member and to maintain the light transmittance from the light source. It came to complete.

That is, the light conversion member of the present invention is a light conversion member made of glass containing phosphor particles dispersed therein, and further contains a heat resistant filler dispersed in the glass. Is characterized in that the relational expression [D ₅₀ / n] between its 50% particle size D ₅₀ and its refractive index n at a wavelength of 633 nm is in the range of 2-20.

The method for producing a light conversion member of the present invention includes a kneading step of kneading glass powder, phosphor particles, a heat-resistant filler, a resin and an organic solvent to form a kneaded product, and molding the obtained kneaded product into a desired shape. And a firing step of firing the molded body of the kneaded product to form a light conversion member, wherein the heat-resistant filler has a 50% particle size D ₅₀ and a wavelength of 633 nm. The relational expression [D ₅₀ / n] with the refractive index n is in the range of 2-20.

  Moreover, the illumination light source of this invention has the light conversion member of this invention, and the light source which can irradiate light outside through this light conversion member, It is characterized by the above-mentioned.

  The liquid crystal display device of the present invention is a liquid crystal display device comprising a liquid crystal display panel and a backlight for illuminating the liquid crystal display panel, and the light conversion member of the present invention and the above-described backlight are used as the backlight. It has the illumination light source which consists of a light source which can irradiate light outside through a light conversion member.

  Since the light conversion member of the present invention suppresses shrinkage during firing and suppresses variations in in-plane light conversion chromaticity, light with less chromaticity unevenness can be obtained. Furthermore, since the light conversion member of the present invention can suppress a decrease in the transmittance of the light conversion member, the light conversion efficiency can be relatively maintained while the amount of light flux is maintained.

  The manufacturing method of the light conversion member of this invention can manufacture the light conversion member of this invention efficiently. And since the illumination light source of this invention uses the light conversion member of this invention, illumination light with little chromaticity nonuniformity is obtained. Since the liquid crystal display device of the present invention uses the illumination light source, it can maintain light emission conversion efficiency, can expect low power consumption, has high color reproducibility, and can provide high-definition expression.

  Hereinafter, the light conversion member of the present invention (hereinafter, also referred to as “the present light conversion member”), the manufacturing method thereof, and the illumination light source will be described.

[Light conversion member]
As described above, the light conversion member is made of glass containing phosphor particles dispersed therein, and further contains a predetermined heat-resistant filler dispersed in the glass. Such a light conversion member transmits a part of the light emitted from the light source, converts the wavelength of the remaining light, and synthesizes the transmitted light and the light having the converted wavelength, thereby obtaining a desired chromaticity. Can be irradiated to the outside. This light conversion member is particularly useful as a light conversion member for converting a blue light source into white. Moreover, as a light source used here, an LED light emitting element is preferable.

(Glass)
The glass used for this light conversion member can be used without particular limitation as long as it is conventionally used as a light conversion member.

  The glass used here preferably has a glass transition point Tg (hereinafter also simply referred to as “Tg”) of 300 to 550 ° C. When the glass transition point is higher than 550 ° C., the firing temperature becomes high during the production process of the present light conversion member, and the uniform dispersibility of the phosphor particles may be reduced by shrinkage in cooling after firing. That is, the amount of phosphor particles present per unit area varies due to the difference in the degree of contraction between the central portion and the outer peripheral portion of the light conversion member, which causes chromaticity unevenness in the surface of the light conversion member. May occur. Or glass and fluorescent substance react and there exists a possibility that the quantum conversion yield of a light conversion member may fall. In order to suppress shrinkage or a decrease in quantum conversion yield, the Tg of the glass is preferably 520 ° C. or lower, more preferably 500 ° C. or lower, and further preferably 480 ° C. or lower.

  On the other hand, when the glass transition point Tg is less than 300 ° C., the firing temperature is low, and the decalcification temperature is higher than the temperature at which the glass flows. Therefore, the carbon content in the light conversion member is increased, and the quantum conversion yield of the light conversion member may be reduced. In addition, the transmittance of the light conversion member is lowered, and the light emission efficiency of the light source may be lowered. The glass transition point Tg is more preferably 340 ° C. or higher, and further preferably 380 ° C. or higher. In this specification, Tg of glass is calculated from a DTA curve.

The glass used here preferably has a Bi ₂ O ₃ —B ₂ O ₃ —ZnO system as a main component. Among them, as represented by mol% based on _{oxides, Bi 2 O 3 3~40%,} B 2 O 3 10~50%, ZnO 0~45%, more preferably glass containing.

_{Further, Bi 2 O 3 3~40%,} B 2 O 3 10~50%, ZnO 0~45%, SiO 2 0~35%, BaO 0~20%, TeO 2 0~20%, Al 2 O 3 _{0~4%, TiO 2 0~5%,} ZrO 2 0~5%, Nb 2 O 5 0~5%, MnO 2 0~1%, CeO 2 0~1%, Li 2 O 0~15%, More preferably, the glass contains Na ₂ O 0-15% and K ₂ O 0-15%.

  This glass preferably consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. Hereinafter, each component of this glass is demonstrated.

Bi ₂ O ₃ is a component that lowers the Tg and raises the refractive index without lowering the chemical durability of the glass, and is an essential component in this system. The content of Bi ₂ O ₃ is preferably _{3 to} 40%. If Bi ₂ O ₃ is less than 3%, the Tg of the glass powder is increased, which is not preferable. More preferably, it is 5% or more. On the other hand, if it exceeds 40%, the glass becomes unstable and tends to be crystallized, which may impair the sinterability. In addition, the absorption edge of the glass shifts to the long wavelength side and absorbs the blue light of the LED element. Also, the refractive index becomes too high and the difference in refractive index from the phosphor increases, so that the luminous efficiency of the LED is increased. May be lowered. The content of Bi ₂ O ₃ is more preferably 3 to 30%, further preferably 5 to 25%.

B ₂ O ₃ is a glass network former and is a component that can stabilize glass, and is an essential component in this system. The content of B ₂ O ₃ is preferably 10 to 50%. If the content of B ₂ O ₃ is less than 10%, the glass becomes unstable, tends to be crystallized, and the sinterability may be impaired. On the other hand, if the content of B ₂ O ₃ exceeds 50%, the chemical durability of the glass may be lowered. The content of B ₂ O ₃ is more preferably 15 to 45%, further preferably 20 to 40%.

  ZnO is a component that lowers Tg and raises the refractive index, and is not an essential component in this system. The content of ZnO is preferably 0 to 45%. If the ZnO content exceeds 45%, it will be difficult to vitrify, and it will be difficult to produce glass. The content of ZnO is more preferably 5 to 40%, further preferably 5 to 35%.

SiO ₂ is a component that increases the stability of the glass and is not an essential component in this system. The content of SiO ₂ is preferably 0 to 35%. If the content of SiO ₂ exceeds 35%, Tg may be high. The content of SiO ₂ is more preferably 0 to 30%, further preferably 0 to 20%.

  CaO, SrO, MgO and BaO alkaline earth metal oxides are components that increase the stability of the glass and lower the Tg, and are not essential components in this system. The total amount of alkaline earth metal oxide is preferably 0 to 20%. If this total amount exceeds 20%, the stability of the glass is lowered. More preferably, the total amount is 18% or less.

TeO ₂ is a component that lowers the Tg, raises the refractive index, raises the weather resistance, and lowers the liquidus temperature, but is not an essential component in the present invention. The content of TeO ₂ is preferably 0 to 20%. If the TeO ₂ content exceeds 20%, the sinterability may be impaired, or the phosphor may be deactivated by reacting with the phosphor during firing. The TeO ₂ content is more preferably 16% or less, further preferably 14% or less, and particularly preferably 12% or less.

Al ₂ O ₃ is a component that improves chemical durability and suppresses reaction with the phosphor during firing, but is not an essential component in the present invention. The content of Al ₂ O ₃ is preferably 0 to 4%. If the Al ₂ O ₃ content exceeds 4%, Tg may be too high, the liquidus temperature may be increased, or the sinterability may be impaired. The content of Al ₂ O ₃ is more preferably 3% or less.

TiO ₂ , ZrO ₂ and Nb ₂ O ₅ are components that increase the refractive index, increase the weather resistance of the glass, and increase chemical durability, and are not essential components in this system. These components are TiO ₂ 0 to 5%, ZrO ₂ 0 to 5%, Nb ₂ O ₅ 0 to 5%, and the total amount is preferably 0 to 5%. If the total amount of these components exceeds 5%, the stability of the glass is lowered, Tg becomes too high, the absorption edge of the glass is shifted to the longer wavelength side, and the blue light of the LED element may be absorbed. There is. This total amount is preferably 4% or less, more preferably 3% or less.

Neither MnO ₂ nor CeO ₂ is an essential component in this system, but it is preferably contained because it functions as an oxidizing agent in the glass. In any case, reduction of Bi ₂ O ₃ in the glass can be prevented, so that this type of glass can be stabilized. Reduction of Bi ₂ O ₃ is not preferable because the glass is colored. Therefore, the content of MnO ₂ and CeO ₂ is preferably 0 to 1%. If the content exceeds 1%, coloring may increase. Preferably it is 0 to 0.5%.

Alkali metal oxides of Li ₂ O, Na ₂ O and K ₂ O are components that lower Tg and are not essential components in this system. The total amount of alkali metal oxides is preferably 0 to 15%. If the total amount exceeds 15%, the refractive index is lowered, and the chemical durability of the glass may be lowered. More preferably, it is 0-10%, More preferably, it is 0-5%.

  The glass may further include a glass that can degas the encapsulated foam. Examples of such elements include elements that can have a plurality of oxidation numbers by changing the valence, such as metal compounds having oxidation catalytic properties such as copper chloride and antimony oxide. The content of these components is preferably 0 to 15%.

The density of the glass is preferably 3.5 to 7.0 g / cm ³ . Outside this range, the difference in specific gravity with the phosphor becomes large, and the phosphor particles are not uniformly dispersed in the glass powder, and conversion efficiency may be reduced when a light conversion member is used. The density is more preferably 3.7 to 6.5 g / cm ³ , and still more preferably 4.1 to 6.0 g / cm ³ .

  The refractive index of the glass is preferably 1.65 to 2.10 at a wavelength of 633 nm. If it is out of this range, the difference in refractive index from the phosphor particles becomes large, and there is a possibility that the conversion efficiency is lowered when the light conversion member is used. The refractive index is more preferably 1.70 to 2.05, still more preferably 1.75 to 2.00.

(Phosphor particles)
If the fluorescent substance particle used for this light conversion member can convert the wavelength of a light source, the kind will not be limited, For example, the well-known fluorescent substance particle used for a light conversion member is mentioned. Examples of such phosphor particles include oxides, nitrides, oxynitrides, sulfides, oxysulfides, halides, aluminate chlorides, halophosphates, and the like. Among the phosphors described above, those that convert blue light into red, green, or yellow are preferable, and those that have an excitation band at a wavelength of 400 to 500 nm and have an emission peak (λ _p ) at a wavelength of 500 to 700 nm are more preferable. preferable.

As long as the light passing through the light conversion member is converted into a desired color, the phosphor only needs to contain one or more compounds selected from the group consisting of the above-mentioned compounds, and a plurality of types of compounds are mixed. May be contained, or any one of them may be contained alone. From the viewpoint of ease of color design, it is preferable to contain any one of them. From the viewpoint of increasing the quantum conversion yield, the phosphor is preferably an oxide or aluminate chloride. The phosphor of oxide or aluminate chloride is more preferably a garnet crystal. Garnet-based crystals are excellent in water resistance and heat resistance, and are hardly deactivated in a slurry or deactivated during firing when undergoing the production process of the present invention described later. Examples of the garnet-based crystal include a composite oxide of yttrium and aluminum (Y ₃ Al ₅ O ₁₂ ; hereinafter abbreviated as YAG in this specification), a composite oxide of lutetium and aluminum (Lu ₃ Al ₅ O ₁₂ ; Hereinafter, it is abbreviated as LAG in this specification.

The average particle diameter (hereinafter abbreviated as 50% particle size in the present specification) D ₅₀ of the phosphor particles is preferably 1 to 30 μm. If the 50% particle size D ₅₀ of the phosphor particles is less than 1 μm, the specific surface area of the phosphor particles is increased, and the phosphor particles may be easily deactivated. The 50% particle size D ₅₀ is more preferably 3 μm or more, further preferably 5 μm or more, and particularly preferably 7 μm or more. On the other hand, when the 50% particle diameter D ₅₀ of the phosphor particles is more than 30 μm, the dispersibility is deteriorated in the light conversion member, the light conversion efficiency is deteriorated, and chromaticity unevenness may occur. Therefore, the 50% particle diameter _{D 50,} and more preferably 20μm or less, more preferably 15μm or less. In the present specification, the 50% particle size D ₅₀ is a value calculated as a 50% value in the integrated% on a volume basis from the particle size distribution obtained by laser diffraction particle size distribution measurement.

(Heat resistant filler)
The heat-resistant filler used in the present light conversion member is a heat-resistant filler having a relational expression [D ₅₀ / n] of 2 to 20 between the 50% particle diameter D ₅₀ and the refractive index n at a wavelength of 633 nm. By including such a heat-resistant filler in the glass, when the light conversion member is produced, shrinkage that occurs during firing can be suppressed, and the uniform dispersibility of the phosphor particles in the light conversion member can be favorably maintained. If the relational expression [D ₅₀ / n] in this heat-resistant filler is less than 2, the light from the light source tends to be scattered, and the light transmittance of the light conversion member tends to decrease. The dispersibility of the resin may decrease, and shrinkage may not be suppressed uniformly. This relational expression [D ₅₀ / n] is preferably in the range of 3 to 18, more preferably 4 to 15.

The heat 50% particle diameter _{D 50} of the filler is 5~30μm is preferred. If it is less than 5 μm, light from the light source tends to be scattered and the light transmittance of the light conversion member may be reduced. If it exceeds 30 μm, the dispersibility of the heat-resistant filler in the light conversion member is reduced, and shrinkage during firing is caused. May not be sufficiently suppressed. The 50% particle size D ₅₀ is more preferably 6 to 25 μm, still more preferably 8 to 22 μm.

  Further, the refractive index n of the heat resistant filler at a wavelength of 633 nm is preferably 1.5 to 2.5. If the refractive index is out of the range, the difference in refractive index from the glass increases, so that the refraction at the interface between the heat-resistant filler and the glass increases and the light from the light source is easily scattered, and the light transmittance of the light conversion member May decrease. The refractive index n of the heat resistant filler is more preferably 1.6 to 2.3, and still more preferably 1.7 to 2.2.

  Moreover, this heat-resistant filler should just have heat resistance with respect to the calcination temperature at the time of manufacture of a light conversion member, for example, an alumina, a zirconia, magnesia etc. are mentioned, Among these, at least 1 type or more is contained. If you do.

  In addition, the refractive index of the heat-resistant filler was measured using a bulk body, and the refractive index n for light having a wavelength of 633 nm was measured using a model 2010 prism coupler manufactured by Metricon.

  As described above, the present light conversion member is configured by dispersing phosphor particles and a heat-resistant filler in glass. In order to sufficiently suppress shrinkage during firing of the light conversion member, when the total amount of glass, phosphor particles and heat-resistant filler is 100%, the heat-resistant filler may contain 3 to 30% by volume fraction. preferable. If the content is less than 3%, the shrinkage may not be sufficiently suppressed, and if it exceeds 30%, the light transmittance of the light conversion member may be reduced, and the utilization efficiency of the light source may be reduced.

  At this time, it is preferable to contain 50 to 96% of glass and 1 to 40% of phosphor particles in volume fraction. With such a content, the light conversion member can be manufactured in a well-balanced manner with the light transmittance from the light source and the light conversion amount of the phosphor particles. It is possible to suppress the occurrence of chromaticity unevenness.

  The quantum conversion yield of the light conversion member is preferably 80% or more. If the quantum conversion yield is less than 80%, the thickness of the light conversion member must be increased in order to obtain a desired color. When the thickness is increased, the transmittance of the light conversion member may be reduced. The quantum conversion yield of the light conversion member is more preferably 85% or more, and still more preferably 90% or more. The quantum conversion yield is expressed as a ratio of the number of photons emitted from the sample as light emission when irradiated with excitation light and the number of photons absorbed by the sample. The number of photons is measured by the integrating sphere method.

  Since this light conversion member can hold | maintain the quantum conversion yield high, even if it makes a light conversion member thin, the function of an above-described light conversion member can be exhibited. The thickness of the light conversion member is preferably 50 to 500 μm. When the thickness of the light conversion member is 50 μm or more, handling of the light conversion member becomes easy, and cracking of the light conversion member can be suppressed particularly when cutting to a desired size. The thickness of the light conversion member is more preferably 80 μm or more, further preferably 100 μm or more, and particularly preferably 120 μm or more. When the thickness of the light conversion member is 500 μm or less, the total light flux transmitted through the light conversion member can be maintained high. The thickness of the light conversion member is preferably 400 μm or less, more preferably 300 μm or less, and particularly preferably 250 μm or less.

  If the phosphor to be used is extremely expensive, the amount of the phosphor to be contained in the light conversion member is to be suppressed as much as possible. Therefore, even if the total amount of light flux is sacrificed, the thickness of the light conversion member can be increased to ensure the light conversion efficiency. There is sex. In that case, the thickness of the light conversion member may be selected between 250 and 500 μm in order to balance the total luminous flux and the light conversion efficiency.

  The planar shape of the light conversion member is not particularly limited. For example, when the light conversion member is used in contact with the light source, the shape of the light conversion member is manufactured according to the shape of the light source in order to prevent light leakage from the light source. Since the light source is generally rectangular or circular, the light conversion member is also preferably rectangular or circular. The light converting member is preferably plate-shaped, that is, the cross-sectional shape is rectangular. The smaller the variation in the plate thickness within the light conversion member, the smaller the in-plane color variation, which is preferable.

[Production Method of Light Conversion Member]
The present light conversion member is preferably made of a sintered body of a mixed powder of glass powder, phosphor particles and heat-resistant filler. The light conversion member is more preferably composed of a sintered body obtained by firing a kneaded product obtained by kneading the mixed powder, a resin and an organic solvent, and the kneaded product is applied to a transparent resin. More preferably, it is made of a glass sheet obtained by sintering a green sheet obtained by drying. In the present specification, the mixture of the resin and the organic solvent may be referred to as a vehicle.

  Thus, in order to produce this light conversion member as a sintered body, a kneading step of kneading glass powder, phosphor particles, heat-resistant filler, resin and organic solvent to obtain a kneaded product, What is necessary is just to perform sequentially the shaping | molding process shape | molded in a desired shape, and the baking process which bakes the molded object of a kneaded material and makes it a light conversion member.

(Kneading process)
The kneading step in the present invention involves kneading glass powder, phosphor particles, heat-resistant filler, resin and organic solvent into a kneaded product (slurry), and it is sufficient that these raw materials can be kneaded uniformly. In this kneading, a known kneading method, for example, kneading using a dissolver, a homomixer, a kneader, a roll mill, a sand mill, an attritor, a ball mill, a vibrator mill, a high-speed impeller mill, an ultrasonic homogenizer, a shaker, etc. Good.

  The glass powder used here may be prepared by mixing a plurality of known glass powders so as to satisfy the above-mentioned glass composition, or by mixing and mixing components so as to have predetermined thermal characteristics. Then, it may be prepared by melting in an electric furnace or the like, rapidly cooling to produce glass having a predetermined composition, pulverizing and classifying it.

At this time, the glass powder preferably has a 50% particle size D ₅₀ of less than 2.0 μm. When the 50% particle size D ₅₀ is 2.0 μm or more, the phosphor particles and the heat-resistant filler are not uniformly dispersed in the glass powder, so that the light conversion efficiency decreases when the light conversion member is used, or the shrinkage amount during firing May increase. The 50% particle size D ₅₀ is more preferably 1.5 μm or less, and still more preferably 1.4 μm or less.

The maximum particle diameter _Dmax of the glass powder is preferably 30 μm or less. When the maximum particle size D _max is more than 30 μm, the phosphor particles and the heat-resistant filler are difficult to be uniformly dispersed in the glass powder, and when the light conversion member is produced, the light conversion efficiency of the phosphor is reduced, or during firing. There is a risk that the amount of shrinkage of the material increases. D _max is more preferably 20 μm or less, and still more preferably 15 μm or less. In the present specification, D _max is the value of the maximum particle size calculated by laser diffraction particle size distribution measurement.

  The phosphor particles and the heat-resistant filler are the particles described in the light conversion member.

  As the resin, ethyl cellulose, nitrocellulose, acrylic resin, vinyl acetate, butyral resin, melamine resin, alkyd resin, rosin resin, or the like can be used. As the organic solvent, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, ethers, ketones or esters can be used. In order to improve the strength of the green sheet, the vehicle preferably contains a butyral resin, a melamine resin, an alkyd resin, a rosin resin, or the like.

  When kneading the above components, when the total amount of the phosphor particles, the heat-resistant filler and the glass powder is 100%, the content of each component in the mixed powder is a volume fraction, and the phosphor particles are 1 to 40%. The heat-resistant filler is preferably 3 to 30%, and the glass powder is preferably 50 to 96%.

  If phosphor particles are contained at 1% or more and glass powder at 96% or less, the quantum conversion yield can be increased, incident light can be efficiently converted, and light of a desired color can be obtained. The volume fraction of the phosphor particles is more preferably 5% or more, further preferably 7% or more, and particularly preferably 10% or more. The volume fraction of the glass powder is more preferably 91% or less, further preferably 87% or less, and particularly preferably 83% or less.

  If the volume fraction of the phosphor particles is more than 40% and the volume fraction of the glass powder is less than 50%, the sinterability of the mixture of the phosphor particles and the glass powder is impaired, and the transmittance of the light conversion member is low. There is a risk. Moreover, there is a possibility that light of a desired color cannot be obtained due to an increase in converted fluorescent light. The volume fraction of the phosphor particles is more preferably 35% or less, still more preferably 30% or less, and particularly preferably 25% or less. The volume fraction of the glass powder is more preferably 55% or more, further preferably 60% or more, and particularly preferably 65% or more.

  Moreover, it is preferable that the volume fraction of the heat-resistant filler is 3% or more because the shrinkage during firing of the light conversion member can be efficiently suppressed, and the state in which the phosphor particles are uniformly dispersed can be maintained. The volume fraction of the heat-resistant filler is more preferably 4% or more, further preferably 5% or more, and particularly preferably 7% or more. Further, if the volume fraction of the heat-resistant filler exceeds 30%, the sinterability of the mixed powder is impaired, and the transmittance of the light conversion member may be lowered. The volume fraction of the heat resistant filler is preferably 28% or less, more preferably 26% or less, still more preferably 20% or less, and particularly preferably 15% or less.

  A vehicle composed of a resin and an organic solvent may be made into a slurry by mixing the above mixed powder with an amount of viscosity that can be molded into a predetermined shape in the next molding step.

(Molding process)
In the molding step of the present invention, the kneaded product obtained in the kneading step is molded into a desired shape to form a kneaded product. The molding method is not particularly limited as long as a desired shape can be imparted, and examples thereof include known methods such as a press molding method, a roll molding method, and a doctor blade molding method. A green sheet obtained by a doctor blade molding method is preferable because a light conversion member having a uniform film thickness can be efficiently produced in a large area.

  The green sheet can be manufactured, for example, by the following process. Glass powder, phosphor particles and heat-resistant filler are kneaded in a vehicle and defoamed to obtain a slurry. The obtained slurry is coated on a transparent resin by a doctor blade method and dried. After drying, it is cut into a desired size and the transparent resin is peeled off to obtain a green sheet. Furthermore, by pressing these to form a laminate, a molded body having a desired thickness can be secured.

  Here, the transparent resin for applying the slurry is not particularly limited as long as it has releasability. The transparent resin used here is preferably a transparent film having a uniform thickness so that a green sheet having a uniform thickness can be obtained. Examples of such a transparent film include a PET film. It is done.

(Baking process)
The firing step of the present invention is a step in which the molded body of the kneaded product obtained in the molding step is sintered by firing to obtain a light conversion member. Firing in this firing step is to sinter the mixed powder to obtain a glass containing phosphor particles and heat-resistant filler dispersed therein, and the glass body may be produced by a known firing method.

As long as the firing step can be performed to form a glass body, the conditions are not particularly limited, but the firing atmosphere is preferably a reduced pressure atmosphere of 10 ³ Pa or less or an atmosphere having an oxygen concentration of 1 to 15%. The firing temperature is preferably in the range of 400 to 650 ° C., and the firing time is preferably in the range of 1 to 10 hours. In the manufacturing method of the light conversion member of this invention, when implemented outside the said range, there exists a possibility that the quantum conversion yield of a light conversion member may fall.

The light conversion member obtained as described above contains a heat-resistant filler having predetermined characteristics, thereby suppressing the shrinkage during firing, thereby suppressing in-plane light conversion chromaticity variation. Light with less unevenness can be obtained. Furthermore, this light conversion member can suppress a decrease in the transmittance thereof, while maintaining the light flux amount, and containing a material whose [D ₅₀ / n] deviates from the above definition as a heat-resistant filler with a light emission conversion efficiency. Higher than that can be maintained.

[Light source]
The illumination light source of the present invention includes the above-described light conversion member and a light source capable of irradiating light to the outside through the light conversion member.

  By combining the light conversion member and the light source obtained as described above, it can be used as an illumination light source that emits a desired color. The light conversion member is preferably disposed in contact with the light source because it prevents light leakage. Moreover, as a light source, an LED light emitting element is preferable and a blue LED light emitting element is more preferable. If an LED light emitting element is used as a light source, it can be used as an LED illumination light source.

[Liquid Crystal Display]
Furthermore, a case where a liquid crystal display device is configured by combining the above-described light conversion member with a light source will be described. That is, the liquid crystal display device in the present embodiment is a liquid crystal display device including a liquid crystal display panel and a backlight that illuminates the liquid crystal display panel, and the light conversion member and the light conversion member are used as a backlight. And an illumination light source comprising a light source capable of irradiating light to the outside.

(Backlight)
The backlight used in the present embodiment includes the above-described light conversion member and a light source that can emit light to the outside through the light conversion member.
By combining the light conversion member and the light source obtained as described above, it can be suitably used as a backlight for a liquid crystal display device capable of obtaining a high luminance and a wide range of color reproducibility. The light conversion member is preferably disposed in contact with the light source because it prevents light leakage. Moreover, as a light source, an LED light emitting element is preferable, a blue LED light emitting element is more preferable, and a backlight capable of emitting white light is preferable.

(LCD panel)
The liquid crystal display panel used in the present embodiment is not particularly limited as long as it is a known liquid crystal display panel. The liquid crystal display panel displays an image by providing an alignment film between two glass plates provided with a polarizing filter, changing the direction of liquid crystal molecules by applying a voltage, and increasing or decreasing light transmittance.

  In the liquid crystal display device configured as described above, since the illumination light source of the present invention is used for the backlight, for example, the liquid crystal display panel can be illuminated with bright white light having a wide color gamut based on the three primary colors of light. Therefore, pure white with high luminance can be obtained on the display screen of the liquid crystal display panel, color reproducibility is good, and the quality of the display screen can be improved.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example and a comparative example, this invention is limited to these Examples and manufacture examples, and is not interpreted. Examples (Examples 1 to 4, 7 to 18) and comparative examples (Examples 5 to 6) of the light conversion member of the present invention are shown in Tables 2 and 3.

As phosphor particles, a Ce-activated YAG phosphor having a 50% particle size D ₅₀ of 10 μm, a refractive index at 633 nm of about 1.9 nm and a phosphor peak wavelength of about 555 nm when excited, and a 50% particle size D ₅₀ are 50% particle size D _50. Two kinds of Eu-activated CASN phosphors having a refractive index at 11 μm and a wavelength of 633 nm of about 2.3 and 460 nm and a phosphor peak wavelength of about 628 nm were used. In Tables 2 and 3, they are abbreviated as “YAG” and “CASN”, respectively.

The heat-resistant filler, the refractive index 18μm 50% particle diameter _{D 50,} heat-resistant filler 1,50% particle diameter _{D 50} of refractive index at a wavelength of 633nm is made of a single crystal alumina which is 1.76 is 3 [mu] m, at a wavelength of 633nm 1 .76 heat-resistant filler 2 made of single crystal alumina, ₅₀ % particle size D ₅₀ is 12 μm, heat-resistant filler 3 made of YAG having a refractive index of 1.83 at a wavelength of 633 nm, and 50% particle size D ₅₀ is 6 μm, A heat-resistant filler 4 made of magnesia having a refractive index of 1.7 at a wavelength of 633 nm was used. That is, the heat-resistant filler 1 _[D 50 / n] is 10.2, _[D 50 / n] is 1.7 of heat-resistant filler 2, _[D 50 / n] is 6.6 heat-resistant filler 3, heat-resistant filler 4 [D ₅₀ / n] is 3.5.

As glass, what has the following characteristics was obtained by the manufacturing method described below. Glass raw materials were mixed so as to have the composition shown in Table 1 in terms of mol% based on oxide. The glass 1 is heated in an electric furnace to 1200 ° C. in a platinum crucible and melted, and the glasses 2 to 4 are heated in an electric furnace in a gold crucible to 900 ° C. to 1000 ° C., melted, and melted respectively. The liquid was quenched with a rotating roll to form a glass ribbon. The glass ribbon was pulverized with a ball mill, passed through a sieve having a mesh having an opening of 150 μm, and further subjected to air classification to obtain glass powder (glass powder). Represents 50% particle diameter _{D 50} of the glass 1-4 1.4μm, 1.2μm, 1.3μm, was 1.2 [mu] m. The glass transition points Tg of the glass powder were 496 ° C., 420 ° C., 429 ° C., and 415 ° C., respectively. A part of the melt was cooled after molding to obtain a glass plate. The refractive indices n of the glass plate for light having a wavelength of 633 nm were 1.79, 1.97, 1.91, and 1.99, respectively.

The glass transition point Tg of the obtained glass powder was measured using a differential thermal analyzer (manufactured by Rigaku Corporation, trade name: TG8110). The phosphor particles, the particle size _{D 50} of the heat-resistant filler and glass powder, a laser diffraction particle size distribution measurement (manufactured by Shimadzu Corporation, apparatus name: SALD2100) was calculated by.

  Further, the obtained glass plate was processed into a plate shape having a thickness of 2 mm and a size of 20 mm × 20 mm, and both surfaces thereof were mirror-polished to obtain a sample plate, and the refractive index n with respect to light having a wavelength of 633 nm was set as a model 2010 prism manufactured by Metricon. Measurement was performed using a coupler.

(Examples 1-18)
Glass, phosphor particles, and heat-resistant filler were mixed so as to have the ratios shown in Tables 2 to 3, and further kneaded with a vehicle and defoamed to obtain a slurry. This slurry was applied to a PET film (manufactured by Teijin Limited) by the doctor blade method. This was dried in a drying furnace for about 30 minutes, cut into a size of about 7 cm square, and the PET film was peeled off to obtain a green sheet having a thickness of 0.5 to 0.7 mm.

This was placed on a mullite substrate coated with a release agent, decalcified at the demineralization temperature and demineralization time shown in Tables 2 and 3, and fired in an air atmosphere, and then decalcified and then fired as shown in Tables 2 and 3 A light conversion member was produced by firing at a temperature, firing time and firing atmosphere.
In the table, “reduced pressure” has an ultimate vacuum of 10 Pa.

(Test example)
About the obtained light conversion member of Examples 1-18, the plane shrinkage rate, the quantum conversion yield, the chromaticity coordinates x and y, the in-plane chromaticity variations Δx and Δy, and the transmittance were measured. These results are shown in Tables 2-3.

  The plane shrinkage rate was obtained by averaging the vertical and horizontal shrinkage rates of the obtained light conversion member with respect to the vertical and horizontal lengths of the green sheet.

  For the quantum conversion yield of the light conversion member, the central portion of the obtained light conversion member is cut into a size of 1 cm square, and an absolute PL quantum yield measuring device (manufactured by Hamamatsu Photonics, trade name: Quantauru-QY) is used. Then, measurement was performed at an excitation light wavelength of 460 nm. At the same time, chromaticity coordinates x and y are also obtained.

  In-plane chromaticity variations Δx and Δy are obtained by cutting the end of the obtained light conversion member into a size of 1 cm square like the center, measuring the chromaticity coordinates, and then calculating the difference from the chromaticity coordinates in the center. It was obtained by taking.

  The transmittance | permeability of the light conversion member was measured with C light source using the haze measuring apparatus (The Suga Test Instruments company make, brand name: Haze meter HZ-2).

As apparent from Tables 2-3, Examples 1-4 and 7-18 contain the heat-resistant filler specified in the present invention, so the shrinkage rate is suppressed to less than 20%, and the in-plane chromaticity variation Δx, Each Δy is less than 0.02. Moreover, since Examples 1-4 maintain the high quantum conversion yield of 85% or more and the transmittance | permeability of 80% or more, high luminescence conversion efficiency can also be expected.
Since Examples 7-18 use the glass whose refractive index is higher than the glass 1 used in Examples 1-4, the reflectance is high and the transmittance is a low value. Since it is a value closer to the refractive index, the scattering efficiency of the glass / phosphor is lowered, and as a heat-resistant filler, [D ₅₀ / n] is higher in luminescence conversion efficiency than that outside the definition of the present invention. I can expect. Moreover, since the CASN phosphor exhibits large absorption in the wavelength region of the C light source, the transmittance of the light conversion members of Examples 8, 10, 13, 14, 17, and 18 is low.
Further, since the glasses 2 to 4 can be sintered even when the firing temperature is low, a high quantum conversion yield can be obtained even when firing in an air atmosphere without firing in a reduced pressure atmosphere as in Examples 1 to 4. Therefore, a light conversion member can be manufactured at low cost.
However, in Examples 12, 14, 16, and 18, since the value of [D ₅₀ / n] of the heat-resistant filler used is lower than that of the heat-resistant filler 1, the content of the heat-resistant filler is up to 20% by volume. If the amount is increased, the transmittance is significantly lowered, and the quantum conversion yield is also lowered. As a result, a decrease in luminescence conversion efficiency is expected.

  On the other hand, since Example 5 does not contain a heat-resistant filler, the shrinkage rate is as high as over 20%, and the in-plane chromaticity variations Δx and Δy are as large as 0.02 or more, respectively.

In Example 6, since the D _{50 of} the heat resistant filler is as small as 3 μm, the transmittance is less than 80%, the total luminous flux is decreased, and the light emission conversion efficiency may be decreased.

  The light conversion member of the present invention maintains the uniform dispersibility of the phosphor particles by suppressing shrinkage during firing, reduces chromaticity variation, suppresses a decrease in light transmittance of the light source, and emits light. The conversion efficiency can be maintained, which is suitable for use as a lighting application.

Claims (15)

A light conversion member made of glass containing dispersed phosphor particles,
The glass further contains a heat-resistant filler dispersed therein, and the heat-resistant filler has a relational expression [D ₅₀ / n] between its 50% particle size D ₅₀ and its refractive index n at a wavelength of 633 nm is 2. A light conversion member characterized by being in a range of ˜20. 2. The light conversion member according to claim 1, wherein the heat-resistant filler has a 50% particle diameter D ₅₀ of 5 to 30 μm and a refractive index n of the heat-resistant filler at a wavelength of 633 nm is 1.5 to 2.5.   The heat-resistant filler is one or more heat-resistant fillers selected from the group consisting of alumina, zirconia and magnesia, and the volume fraction of the heat-resistant filler contained in the glass is 3 to 30%. The light conversion member according to 1.   The light conversion member according to claim 1, wherein the light conversion member has a thickness of 50 to 500 μm.   The phosphor particles have an excitation band at a wavelength of 400 to 500 nm, an emission peak at a wavelength of 500 to 700 nm, and an oxide, nitride, oxynitride, sulfide, oxysulfide, halide, aluminate The light conversion member according to any one of claims 1 to 4, wherein the light conversion member is one or more compounds selected from the group consisting of chlorides and halophosphates.   The light conversion member according to claim 1, wherein the phosphor particles are garnet crystals. The light conversion member according to claim 1, wherein the phosphor particles have a 50% particle diameter D ₅₀ of 1 to 30 μm.   The light conversion member according to any one of claims 1 to 7, wherein the glass has a glass transition point Tg calculated from a DTA curve of 300 to 550 ° C. The light conversion member according to claim 1, wherein the glass is a Bi ₂ O ₃ —B ₂ O ₃ —ZnO system. The glass is represented by _{mol%, Bi 2 O 3 3~40%,} B 2 O 3 10~50%, optical conversion according to any one of claims 1 to 9 containing 0 to 45% ZnO Element.   The light conversion member according to any one of claims 1 to 10, wherein the light conversion member is a sintered body of a mixed powder of glass powder, phosphor particles and a heat-resistant filler.   An illumination light source comprising: the light conversion member according to claim 1; and a light source capable of irradiating light to the outside through the light conversion member.   The illumination light source according to claim 12, wherein the light source is an LED light emitting element. A kneading step of kneading glass powder, phosphor particles, heat-resistant filler, resin and organic solvent to form a kneaded product, a molding step of molding the obtained kneaded product into a desired shape, and firing the molded product of the kneaded product A process for producing a light conversion member, and a method for producing a light conversion member comprising:
The method for producing a light conversion member, wherein the heat-resistant filler has a relational expression [D ₅₀ / n] of an average particle diameter D ₅₀ and a refractive index n at a wavelength of 633 nm of 2 to 20.   When the total amount of the phosphor particles, the heat-resistant filler and the glass powder is 100%, the phosphor particles are 1 to 40%, the heat-resistant filler is 3 to 30%, and the glass powder is a volume fraction. The manufacturing method of the light conversion member of Claim 14 containing 50 to 96%.