JP6036951B2 - Method for manufacturing phosphor - Google Patents

Description

  The present invention relates to a method for manufacturing a phosphor, and more particularly to a method for manufacturing a phosphor having a nitride as a host crystal.

  Light emission that can emit light of various wavelengths by the principle of color mixing of light by combining the light source light emitted from the light emitting element and the wavelength conversion member that can be excited by this and emit light of a hue different from the light source light Equipment has been developed. For example, when primary light from a short wavelength region corresponding to visible light is emitted from ultraviolet light from a light emitting element, and the red, blue, and green light emitting phosphors are excited by the wavelength conversion member by the emitted light, the light 3 The primary colors of red, blue and green are additively mixed to obtain white light. In particular, green phosphors have a high contribution to white color because of their large contribution to white, and various phosphors have been studied so far.

  In addition, the phosphor is generally used as a component of an electronic device that emits light, and the performance of the electronic device largely depends on the energy conversion efficiency of the phosphor. For this reason, improvement in the energy conversion efficiency of the phosphor has been continuously desired.

In particular, since nitrides and oxynitrides are often stable at high temperatures and chemical substances, a form in which rare earth is introduced into the host crystal is being actively studied. As such a phosphor base material, for example, Si _6-z Al _z O _z N _8-z , M _p Si _{12- (m + n)} Al _{m + n On} N _16-n , M ₂ Si ₅ N ₈ MSiAlN ₃ , AlN, M ₃ Si ₆ O ₁₂ N _2, MSi ₂ O ₂ N _{2 and the} like. However, M is a metal element, and 0 <Z <4.2.

  Since the body color of the phosphor is ideally colorless and transparent, it is considered to be suitable as a phosphor matrix. However, most of the nitrides and oxynitrides actually used industrially have a body color such as brown or gray. Such coloring that causes a decrease in luminance is caused by crystal defects and impurities contained in the host crystal.

Therefore, in conventional phosphors using nitrides and oxynitrides as host crystals, light is absorbed by such crystal defects and impurities, resulting in a decrease in energy conversion efficiency. This can be easily determined from the body color of the phosphor. In particular, the β sialon phosphor represented by the general formula: Si _6-z Al _z O _z N _8-z has insufficient body color vividness.

  Thus, the cause of the phosphor crystal crystal defects and the contamination of impurities is explained as follows. That is, when producing a host crystal of a phosphor composed of nitride and oxynitride, firing at a higher temperature is often required as compared with other host crystals such as oxides. For this reason, atoms constituting the host crystal are detached from the surface of the phosphor, and crystal defects are generated. Further, since the firing is performed in a nitrogen atmosphere or a non-oxidizing atmosphere, there is a possibility that a metal element or the like constituting the base crystal is reduced and the simple substance is generated as an impurity. Furthermore, this simple substance may be oxidized in the air and react with the oxide. Since these crystal defects and impurities absorb light, there is a problem that even the fluorescence emitted by the phosphor is absorbed, and the overall output is reduced.

  In order to compensate for this optical loss, it has been proposed to adjust the shape and size of the particles, and to reduce the impact force applied to the particles in the pulverization step for adjusting them (for example, Patent Documents 1 and 2). . By adjusting the shape and size of the particles, the amount absorbed by the light absorption component can be reduced. However, the element of optical loss remains alive because no improvements have been made to the actual crystal defects. That is, in the methods of these patent documents, since the light absorption component continues to exist, it is not a fundamental solution but remains a superficial solution. Even if the impact force on the crystal matrix in the pulverization step is reduced, an increase in crystal defects on the host crystal can be suppressed, but crystal defects and impurities generated in the process of generating the host crystal cannot be removed.

Also, the synthesis temperature of the phosphor containing the crystal structure of β-type Si ₃ N ₄ and Si _6-z Al _z O _z N _8-z (β sialon) should be in a specific range (1820 ° C to 2200 ° C). Thus, it is disclosed that the metal element M serving as the emission center is dissolved in the base crystal to promote improvement in luminance (Patent Document 3). Although various measures have been taken to improve the brightness as described above, none of the energy loss caused by crystal defects of the host crystal itself has been substantially improved. The current situation is that there is still room for improvement.

JP 2007-326981 A JP 2007-332324 A JP 2007-262417 A

  The present invention has been made to solve the conventional problems. That is, the present inventor has newly found that the light absorption component can be reduced by preventing the decomposition of the base crystal in the firing step, and has completed the present invention. A main object of the present invention is to provide a method for producing a phosphor with reduced light absorption components and improved energy conversion efficiency.

The phosphor according to the embodiment is a phosphor based on a crystal containing at least nitrogen, and the general formula is represented by Si _6-z Al _z O _z N _8-z : Re (Re: activator). 0 <Z <4.2 and the reflectance at the emission peak wavelength is 65% or more.

  Re is at least one selected from the group consisting of manganese, cerium, and europium, and the sum of the molar ratios of Si, Al, and Re is 6, and the phosphor is applied at a partial pressure higher than 100 MPa in a nitrogen atmosphere. In addition to firing, it is preferable that after the firing step of the phosphor, the fired body is further heated to 1400 ° C. to 2000 ° C. in an atmosphere containing hydrogen to perform an annealing treatment.

  The light emitting device according to the embodiment includes an excitation light source and the phosphor that emits light by absorbing a part of light from the excitation light source.

Further, according to the phosphor manufacturing method of the present invention, the general formula of the composition is Si _6-z Al _z O _z N _8-z : Re (Re is selected from the group consisting of manganese, cerium, and europium. It is an activator containing at least one kind, and is a method for producing a phosphor represented by 0 <Z <4.2), wherein the composition represented by the general formula is at a temperature of 1500 ° C. or higher and 2200 ° C. or lower. , A step of firing while applying isotropic pressure in a nitrogen atmosphere of 100 MPa or more, and a step of performing annealing treatment by heating the fired fired body to 1400 ° C. or more and 2000 ° C. or less in an atmosphere containing hydrogen Can be included. Thereby, a high-luminance green-emitting phosphor can be provided.

  According to another phosphor manufacturing method, prior to the firing step, the method includes the step of obtaining the composition by firing a mixture containing a silicon compound, an aluminum compound, and the activator compound. it can.

  According to still another phosphor manufacturing method, the step of obtaining the composition includes firing the mixture at a temperature of 1900 ° C. or higher and 2200 ° C. or lower while applying isotropic pressure in a nitrogen atmosphere of 100 MPa or higher. By doing so, it can be set as the process of obtaining the said composition.

  Furthermore, according to another phosphor manufacturing method, the temperature holding time can be set to 4 hours or more.

  According to still another phosphor manufacturing method, the silicon compound is silicon nitride, the aluminum compound is aluminum nitride, and the activator compound is europium oxide.

  Furthermore, according to another phosphor manufacturing method, the step of obtaining the composition may be a step of firing the mixture in a nitrogen atmosphere having a pressure of 0.5 MPa or more and 207 MPa or less.

  Furthermore, according to another method for producing a phosphor, the step of obtaining the composition can be a step of baking the mixture at a temperature of 1900 ° C. or higher and 2200 ° C. or lower.

  Furthermore, according to another phosphor manufacturing method, the average particle diameters of the silicon compound, the aluminum compound, and the activator compound can be 0.1 μm or more and 15 μm or less, respectively.

  The phosphor according to the embodiment is a phosphor capable of emitting green light when activated by an activator using a crystal containing at least nitrogen as a base material. In particular, by being produced under unique conditions of high temperature and pressure, decomposition of the host crystal can be avoided in the firing step, and as a result, the light absorption component can be effectively reduced. That is, in a phosphor having a host crystal composed of nitride and oxynitride, it is possible to improve the decrease in energy conversion efficiency caused by the light absorption component present inside. Specifically, the reflectance at the emission peak wavelength in the phosphor can be set to 65% or more, which makes it difficult for the host crystal to absorb the fluorescence due to luminescence, and improves the light extraction efficiency from the phosphor to improve the overall light emission. Strength can be improved.

  In addition, regarding the method for producing the phosphor, by setting the nitrogen partial pressure in the atmosphere when firing the mixture of raw materials to 100 MPa or more, generation of crystal defects of the phosphor can be avoided and the light absorption component can be reduced. As a result, the energy conversion efficiency by excitation of the phosphor can be increased, and the absorption of the fluorescence into the host crystal can be reduced, that is, the light loss can be reduced and the output can be improved. Furthermore, by setting the firing temperature to 1500 ° C. to 2200 ° C. in the firing step, the light emission characteristics of the phosphor can be improved, and the luminance can be significantly improved.

  In addition, according to the light emitting device according to the embodiment, the component light contributing to the emitted light can be the fluorescence of the phosphor mounted together with the excitation light source. By using this phosphor as the above-mentioned beneficial phosphor, the luminance of the component light can be improved, the wavelength conversion efficiency can be improved, and the emission characteristics of the emitted light from the light emitting device can be relatively improved.

The emission spectrum of the fluorescent substance which concerns on an Example and Comparative Examples 1-2 is shown. The reflection spectrum of the fluorescent substance which concerns on an Example and Comparative Examples 1-2 is shown. The reflection spectrum of the fluorescent substance which concerns on an Example and Comparative Examples 1, 3, and 4 is shown. FIG. 4A is a perspective view and FIG. 4B is a cross-sectional view of the light-emitting device according to Embodiment 1. FIG. FIG. 5A is a plan view and FIG. 5B is a cross-sectional view of a light-emitting device according to Embodiment 2. FIG. FIG. 6A is a perspective view and FIG. 6B is a cross-sectional view of a light-emitting device according to Embodiment 3. FIG. 7 is a cross-sectional view of a light emitting device according to Embodiment 4. FIG. 8A is a cross-sectional view of the light emitting device according to Embodiment 5, and FIG. 8B is another cross-sectional view according to Embodiment 5. 10 is a cross-sectional view of a light emitting device according to Embodiment 6. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a phosphor manufacturing method for embodying the technical idea of the present invention, and the present invention specifies the phosphor manufacturing method as follows. do not do. In addition, the member shown by the claim is not what specifies the member of embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It's just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. In addition, the contents described in some examples and embodiments may be used in other examples and embodiments. In the present specification, the “light absorption component” means a crystal defect or an impurity that exists in the phosphor and absorbs light emitted from the phosphor.
(Embodiment 1)

  The phosphor according to the first embodiment uses a nitride containing at least nitrogen, silicon, and aluminum as a base crystal, and the base crystal further contains at least one activator as a luminescent center.

  As described above, phosphors having excellent thermal and chemical stability and high energy conversion efficiency can be obtained by including silicon and aluminum as elements constituting the host crystal and containing at least one activator as the emission center. can get. Furthermore, various luminescent colors can be obtained by adding other elements or adjusting the ratio of silicon and aluminum. In addition, the emission wavelength region can be changed by changing the activator to be contained in the base crystal. In particular, the activator is preferably at least one selected from the group consisting of manganese, cerium, and europium, whereby the activator can be stably dissolved in the host crystal. In the phosphor according to the first embodiment, the rare earth europium is used as the emission center. However, it is not limited only to europium, and a part thereof can be replaced with other rare earth metals or alkaline earth metals to be co-activated with europium.

  Further, the above phosphor absorbs the wavelength in the short wavelength side region of near ultraviolet or visible light, and is activated by the activator to emit green light. In this specification, blue light from the near ultraviolet region refers to a region of 250 to 470 nm, although not particularly limited. In particular, a range of 290 nm to 460 nm is preferable. Specifically, the phosphor is excited by an excitation light source having the above wavelength, and includes a light emission peak wavelength in a wavelength range of 500 nm or more and 580 nm or less. The phosphor is characterized in that the reflectance at the wavelength at the emission peak is 65% or more. That is, the energy conversion efficiency can be increased by reducing the light absorption component in the phosphor. Note that it is not necessary that the reflectance is continuously 65% or more in the range of 500 nm to 580 nm.

As a phosphor according to the first embodiment, a phosphor having a general formula of Si _6-z Al _z O _z N _8-z : Re (Re: activator) and having europium as the emission center is taken as an example. . In the phosphor, Si is a silicon element, Al is an aluminum element, O is an oxygen element, N is a nitrogen element, and the range of z satisfies 0 <Z <4.2. By setting the specific composition element and composition ratio as described above, the half-value width of the emission spectrum is narrow, in other words, a phosphor having a bright emission color can be obtained.

However, if the composition ratio of the phosphor is in the vicinity of the above range, it has sufficient characteristics to withstand practical use. Therefore, the range of z is not limited to this. In addition, the phosphor of the first embodiment can adjust the color tone and luminance by changing the elemental composition ratio of O and N. Furthermore, the emission spectrum and intensity can be finely adjusted by changing the molar ratio of cation to anion in (Si + Al) / (O + N). Although this adjustment method is not particularly limited, it can be achieved, for example, by performing a process such as vacuum baking and desorbing N and O. Therefore, the peak wavelength can be intentionally displaced by adjusting the composition ratio. Moreover, the phosphor composition may contain at least one element selected from the group consisting of Li, Na, K, Rb, Cs, Mn, Re, Cu, Ag, and Au. Further, other elements may be mixed to such an extent that the characteristics of the phosphor are not impaired.
(Production method)

  The phosphor according to the first embodiment is characterized in that the reflectance at the emission peak wavelength is increased to 65% or more by heating the phosphor based on nitride or oxygen-containing oxynitride under high pressure. It is what. This is a characteristic obtained by firing a raw material in which at least a silicon-containing compound, an aluminum-containing compound, and an activator-containing compound are mixed while applying substantially isotropic pressure in an atmosphere having a nitrogen partial pressure of 100 MPa or more. It is an effect. Further, applying pressure isotropically means applying substantially equal pressure to the object to be processed from substantially all directions. As will be described in detail later, it is preferable to fire the mixed raw material at a temperature of 1900 ° C. to 2200 ° C. almost simultaneously with pressurization. Furthermore, the holding time of the firing temperature is 4 hours or longer, more preferably 8 hours or longer. A detailed manufacturing method will be described below.

  First, as a raw material of the phosphor, a simple substance of an element contained in the composition of the phosphor, an oxide, a carbonate or a nitride is used, and each raw material is weighed so as to have a predetermined composition ratio.

Regarding a specific phosphor material, Si having a phosphor composition preferably uses silicon oxide or nitride as a silicon-containing compound, but an imide compound or an amide compound can also be used. For _{example, SiO 2, Si 3 N 4} , and the like. On the other hand, it is possible to obtain a phosphor with good crystallinity at low cost by using only Si. The purity of the raw material Si is preferably 2N or higher, but may contain different elements such as Li, Na, K, B, and Cu. Furthermore, a part of Si can be replaced with Ge, Sn, Ti, Zr, and Hf. In the first embodiment, silicon nitride is used. In addition, a part of silicon nitride may be replaced with the above silicon oxide, zeolite, polysilazane, metal silicon, or the like. Or you may mix and use 2 or more types from the said raw material.

On the other hand, Al having a phosphor composition is preferably used alone, but a part thereof can be substituted with Group III elements Ga, B, Tl, In, V, Cr, and Co. However, it is possible to obtain a phosphor that is inexpensive and has good crystallinity by using only Al. Further, Al nitride, Al oxide, imide, amide, nitride and various salts may be used as the aluminum-containing compound. Examples include Al ₂ O ₃ , Al (NO ₃ ) ₃ · 9H ₂ O, AlN, and the like. It is better to use purified materials, but the process can be simplified using commercially available products. In the first embodiment, aluminum nitride is used. In addition to the above raw materials, metallic aluminum or the like may be used, and two or more kinds of raw materials may be mixed.

Further, Eu as the activator is preferably used alone, but halides, oxides, carbonates and the like can be used. Further, a part of Eu may be replaced by Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or the like. Moreover, when using the mixture which requires Eu, a compounding ratio can be changed as desired. Thus, by replacing a part of Eu with another element, the other element acts as a co-activator. As a result, the color tone can be changed, and the light emission characteristics can be adjusted. Europium mainly has bivalent and trivalent energy levels, but the phosphor of Embodiment 1 uses Eu ²⁺ as an activator.

Moreover, although it is better to use the purified Eu compound as a raw material, a commercially available product may be used. Specifically, europium oxide Eu ₂ O ₃ , metal europium, europium nitride, or the like can be used as the Eu compound. Europium oxide preferably has a high purity, and commercially available products can also be used.

  Furthermore, elements to be added as necessary are usually added as oxides or hydroxides, but are not limited thereto, and may be metals, nitrides, imides, amides, or other inorganic salts, , It may be contained in other raw materials in advance. Each raw material has an average particle size of about 0.1 μm or more and 15 μm or less, more preferably about 0.1 μm to 10 μm. From the viewpoint of controlling the diameter and the like, and having a particle size in the above range, the particle size in the above range can be achieved by grinding in a glove box in an argon atmosphere or a nitrogen atmosphere.

  The raw material is preferably purified. This is because no purification process is required, and the phosphor manufacturing process can be simplified and an inexpensive phosphor can be provided.

  Among the above-described raw materials, a predetermined amount of Si nitride and Al nitride as the base material and Eu oxide as the activator are measured. That is, these raw materials are weighed and mixed until they become uniform so that the composition ratio of the above general formula is obtained. Alternatively, an additive material such as a flux is appropriately added to these raw materials, and mixed by a wet or dry method using a mixer.

  The mixer can be pulverized using a pulverizer such as a vibration mill, a roll mill, a jet mill, or the like, in addition to a ball mill that is usually used industrially, to increase the specific surface area. Moreover, in order to keep the specific surface area of the powder within a certain range, classification is performed using a wet type separator such as a sedimentation tank, a hydrocyclone, and a centrifugal separator, and a dry classifier such as a cyclone and an air separator. You can also

  The mixed raw materials are packed in a crucible made of a material such as boron nitride (BN) and fired in a nitrogen atmosphere. As another firing atmosphere, an inert gas such as argon can be introduced. The firing pressure is preferably from 0.5 MPa to 207 MPa, and the firing temperature is preferably from 1900 ° C. to 2200 ° C., and the sintering treatment is performed for about 8 hours to 36 hours.

  The fired body is again put into the crucible, and isotropically pressurized and heat-treated. Specifically, it is preferable that the partial pressure of nitrogen is 100 MPa or more and the combustion temperature is 1500 ° C. to 2200 ° C. with a hot isostatic press. The pressure and heat treatment are preferably 0.5 hours to 8 hours. Furthermore, after the obtained fired body is pulverized, it can be annealed by heating at a firing temperature of 1400 ° C. to 2000 ° C. for 2 hours to 8 hours in a mixed atmosphere of nitrogen and hydrogen. Thus, it is preferable to perform annealing after heating and substantially isotropic pressurization, since the brightness of the phosphor after purification can be remarkably improved. Further, the obtained fired body is pulverized, dispersed, filtered, and the like to obtain a target phosphor powder. Solid-liquid separation can be performed by industrially used methods such as filtration, suction filtration, pressure filtration, centrifugation, and decantation. Drying can be achieved by industrially used apparatuses and methods such as a vacuum dryer, a hot air heating dryer, a conical dryer, and a rotary evaporator.

In addition, in the pressurization process with a hot isostatic press, the powdery mixed raw material is sealed in an airtight container made of a material that is airtight to the pressure medium gas, degassed, and then approximately isotropic. Pressure may be applied. As a result, not only the powder but also a phosphor which is densified and becomes a dense sintered body is obtained. Furthermore, it is preferable to apply pressure and heat to the object to be processed almost simultaneously. Thus, the powder material can be joined simultaneously with the pressure sintering. However, the temperature may be increased after the filling container is preheated and sufficiently softened in advance. Thereby, the deformability of the container due to heating can be increased, and damage to the container can be avoided and the influence on the internal object to be processed can be prevented.
(Effect of hot isostatic pressing)

  By substantially isotropically pressurizing the mixed raw material within the above pressure or temperature range, each raw material can be sintered while being diffused. In particular, defects such as pores can be reduced during sintering, and deformation of the structure can be prevented. On the other hand, if the object to be processed has pores formed inside, the pores can be crushed by isotropic pressure and simultaneously diffused to disappear. In particular, if the hole is an inner hole that is not in communication with the surface and is closed to the outside, a high effect can be obtained and the density of the object to be processed can be increased. That is, sintering while preventing the generation of residual vacancies and removal of the residual vacancies can be performed substantially simultaneously.

  In addition, due to the synergistic effect of pressurization and heating within the pressure or temperature range specified above, sintering and diffusibility of the powder can be promoted and internal defects can be effectively removed. In particular, by applying substantially isotropic pressure, the diffusibility inside the mixed raw material can be further promoted, so that deformation of the outer shape of the material can be reduced. Alternatively, since substantially equal pressure is applied to the raw material mixture from almost all directions of the mixed raw material, it contracts in a similar manner until the vacancies inside the mixed material disappear. That is, since the pressure is evenly applied to the uneven portion, the shape does not change substantially. As a result, the defect structure existing inside can be eliminated while maintaining the particle size of the phosphor. Thus, it is preferable that the sintered body can be densified by applying a substantially isotropic pressure combustion sintering treatment under specific conditions.

  The atmosphere sintering in the above pressurization and heat treatment can use a mixed gas of argon and nitrogen or nitrogen gas. This is preferable because the reaction between the pressure medium gas and the object to be processed can be promoted and sintered. Further, it is preferable because the thermal decomposition of the nitride crystal can be effectively prevented. Specifically, by setting the nitrogen partial pressure during firing to 100 MPa or more, generation of crystal defects on the surface of the host crystal and reduction of elements constituting the host crystal are effectively suppressed. As a result, the generation of the light absorption component can be significantly suppressed.

On the other hand, as a conventional technique, in a method for producing a phosphor having an oxide or oxynitride as a base, particularly a phosphor represented by the general formula: Si _6-z Al _z O _z N _8-z , It is known to heat in a nitrogen atmosphere or a non-oxidizing atmosphere and hold at a temperature of 1850 to 2050 ° C. for 9 hours or more. The pressure during heating is disclosed as 0.3 to 4 MPa, which is significantly lower than the pressure (100 MPa) according to the first embodiment.

  Furthermore, in the conventional manufacturing method, there are no specific provisions relating to the pressurized environment. In general, press processing applied to pressurization is usually performed from one axial direction, and thus the volume of the object to be processed is compressed and changed in the pressurizing direction. This leads to the fusion of the phosphors, necessitating a pulverization step, which leads to the generation of crystal defects. In addition, the above-described conventional pressure range is not sufficient if an internal defect structure caused by the light absorption component is pressurized to such an extent that an improvement effect can be obtained. That is, it is difficult to erase the light absorption component. In addition, if the pressure is further increased by conventional press treatment and compression is attempted until the voids disappear, the initial shape will be greatly destroyed, and the adverse effects of particle size deformation and particle fusion will be lost. As described above.

  The present inventor has studied the heating and pressurizing conditions, and it is novel that the reflectance at the emission wavelength of the phosphor is greatly increased by setting the atmosphere during firing to a nitrogen atmosphere and making the partial pressure higher than 100 MPa. I found it. That is, by increasing the nitrogen partial pressure, the separation of nitrogen atoms from the host crystal can be suppressed, and as a result, the light absorption component contained in the phosphor can be reduced.

  The prior art discloses that the raw material is heated in a plurality of times. As the second and subsequent heating conditions, for example, the temperature is 1820 to 2200 ° C., the atmospheric pressure is 0.1 MPa to 100 MPa, and the holding time is 1 hour or more.

  The manufacturing method of the phosphor of the first embodiment includes a unique process for performing isotropic high-pressure treatment almost simultaneously with heating, so that the quality can be improved even if the number of reaction steps from the raw material to the purification is reduced. A high phosphor can be obtained. However, it is possible to purify a phosphor with higher quality by heating in multiple steps as described above. Even in this case, it is preferable to heat and press under the specific nitrogen partial pressure and within the temperature range. Thereby, the detachment | leave of the nitrogen atom from a base crystal can be suppressed. Specific firing conditions are preferably heating at 1500 ° C. to 2200 ° C. in a nitrogen atmosphere with a nitrogen partial pressure of 100 MPa or more. Thereby, the reflectance at the emission wavelength of the phosphor can be increased. In addition, the phosphor containing a large amount of light-absorbing components obtained by the conventional manufacturing method is subjected to heat treatment at 1500 ° C. to 2200 ° C. under the step of Embodiment 1, that is, a nitrogen partial pressure of 100 MPa or more. Thus, the emission characteristics of the phosphor can be greatly improved. That is, in the manufacturing process of the phosphor, a phosphor with improved quality can be obtained by including a substantially isotropic pressurization process having the above specific conditions in at least one of the manufacturing processes.

  The reduction of the light absorption component in the phosphor is revealed by the reflection spectrum. Specifically, if the reflectance at the emission peak wavelength shows high reflectivity, it means that the fluorescence generated by excitation is not absorbed into the phosphor but is emitted to the outside. That is, the excitation energy is converted into fluorescence with high efficiency, indicating that the light extraction efficiency is high. That is, it can be interpreted that the light absorption component that induces light loss in the phosphor is reduced.

For the reflectance measurement of the phosphor according to the first embodiment, a reflectance measuring device manufactured by Nichia Corporation was used. The reflectance measuring method will be described below. A xenon lamp is used as the light source, and light from the light source is introduced into the first monochromator. Only the target wavelength of the introduced light is selected by the first monochromator and irradiated to the sample for which the reflectance is to be obtained. The light reflected by the sample is introduced into the second monochromator, and the second monochromator selects the same wavelength as that selected by the first monochromator. The light selected by the second monochromator is introduced into the photomultiplier tube and the light intensity is measured. Subsequently, the wavelength selected by the first monochromator and the second monochromator is changed synchronously, and the intensity of light in the desired wavelength range is measured. The reference sample of reflectance is calcium hydrogen phosphate (CaHPO ₄ ), and the intensity of light reflected from the reference sample is measured in the same procedure as the above-described sample. The reflectance at each wavelength was determined by calculating the measured light intensity using the following formula.

（結晶）

(crystal)

Moreover, it is preferable that most of the phosphors have crystals. For example, since the glass body (amorphous) has a loose structure, there is a possibility that the component ratio in the phosphor is not constant and chromaticity unevenness occurs. Therefore, in order to avoid this, it is necessary to control the reaction conditions in the production process to be strictly uniform. On the other hand, since the phosphor according to the first embodiment can be a powder or a particle having a crystal instead of a glass body, it is easy to manufacture and process. Further, this phosphor can be uniformly dispersed in an organic medium, and adjustment of a light emitting plastic or a polymer thin film material can be easily achieved. Specifically, in the phosphor according to Embodiment 1, at least 50 wt% or more, more preferably 80 wt% or more has crystals. This indicates the proportion of the crystalline phase having luminescent properties, and if it has a crystalline phase of 50% by weight or more, light emission that can withstand practical use can be obtained. Therefore, the more crystal phases, the better. Thereby, the light emission luminance can be increased and the workability is improved.
(Particle size)

  Considering mounting in a light emitting device, the particle size of the phosphor is preferably in the range of 1 μm to 30 μm, more preferably 2 μm to 20 μm. Moreover, it is preferable that the phosphor having this average particle diameter value is contained frequently. Furthermore, the particle size distribution is preferably distributed in a narrow range. By using a phosphor having a large particle size and having small particle size and particle size distribution variations and optically excellent characteristics, color unevenness is further suppressed and a light emitting device having a good color tone can be obtained. Therefore, a phosphor having a particle size in the above range has high light absorption and conversion efficiency. On the other hand, a phosphor having a particle size smaller than 2 μm tends to form an aggregate.

The particle size is F.D. S. S. S. The average particle diameter obtained by the air permeation method in No (Fisher Sub Sieve Sizer's No). Specifically, in an environment with an air temperature of 25 ° C. and a humidity of 70%, a sample of 1 cm ³ is weighed, packed in a special tubular container, and then dried with a constant pressure, and the specific surface area is read from the differential pressure and averaged. It is a value converted into a particle size.
(Example)

As an example of the method for manufacturing the phosphor according to the first embodiment, in which the general formula is Si _6-z Al _z O _z N _8-z (0 <Z <4.2) below, Si _5.775 Al _0.210 Eu _0.015 This production method will be described by _taking O _0.023 N _7.910 as an example. The phosphors of the examples were produced through three firings mainly under atmospheres with different conditions. However, the following examples illustrate phosphors for embodying the technical idea of the present invention and their manufacturing methods, and the present invention does not specify the phosphors and their manufacturing methods as follows. .

  As the raw material powder, silicon nitride (E10 grade) manufactured by Ube Industries, aluminum nitride (F grade) manufactured by Tokuyama, and europium oxide (RU grade) manufactured by Shin-Etsu Chemical Co., Ltd. were used. These raw materials were blended in proportions of 70.6% by mass, 22.5% by mass, and 6.9% by mass, respectively, and mixed by a ball mill method using a silicon nitride sintered ball and a nylon pot. Subsequently, it was passed through a sieve having an opening of 308 μm. This raw material was put into a boron nitride crucible, and heated at 2020 ° C. for 8 hours under a partial pressure of nitrogen of 0.9 MPa using a carbon heater electric furnace (primary firing). The phosphor obtained by heating was lightly pulverized in an agate mortar and passed through a sieve having an opening of 308 μm.

The phosphor thus obtained was put into a boron nitride crucible, and heated at 1500 ° C. for 4 hours (secondary firing) at a nitrogen partial pressure of 191 MPa using a hot isostatic pressing device manufactured by Kobe Steel. The heated phosphor was lightly pulverized in an agate mortar and passed through a sieve having an opening of 308 μm. Subsequently, the atmosphere was changed to a mixture of nitrogen and hydrogen at normal pressure and heated at 1500 ° C. for 4 hours (tertiary firing). The phosphor obtained by heating was lightly pulverized in an agate mortar and passed through a sieve having an opening of 308 μm. A reflectance measuring device manufactured by Nichia Corporation was used for the reflectance measurement. The reflectance at each wavelength was determined using calcium hydrogen phosphate (CaHPO ₄ ) as a reference sample for reflectance.
(Comparative example)

  The same raw material as in the above example was weighed by the same amount and subjected to primary firing under the same conditions. The obtained phosphor is referred to as Comparative Example 1. In the phosphor of Comparative Example 2, the same raw material as in Example 1 was further mixed with the phosphor obtained in Comparative Example 1 at a ratio of 10% weight (fired body): 90% by weight (raw material). This was obtained through a firing step under the same conditions as the primary firing of the example.

  Table 1 shows the light emission characteristics such as particle diameter, powder luminance, and reflectance in the phosphor powders of Examples and Comparative Examples 1 and 2. FIG. 1 shows the emission spectrum of each phosphor, and FIG. 2 shows the reflection spectrum. As shown in FIG. 1, the phosphors of the examples have higher emission intensity than the phosphors of Comparative Examples 1 and 2. Also, as shown in FIG. 2 and Table 1, the reflectance of the phosphor of the example is higher than the reflectances of Comparative Examples 1 and 2. Specifically, in the phosphor of the example, the reflectance at the emission peak wavelength is 65% or more, and specifically exceeds 70%. That is, it can be seen that in the phosphor subjected to the hot isostatic pressing at a nitrogen partial pressure of 100 MPa or more, the light absorption component is decreased and the reflectance at the emission peak wavelength is greatly increased. This increase in reflectance at the emission peak wavelength contributes to a significant improvement in powder luminance as shown in Table 1.

  FIG. 3 is a graph showing the reflectance of the phosphors produced by the four types of manufacturing methods. That is, the data corresponding to the example in the figure is the data of the phosphor obtained through the phosphor manufacturing method according to the above example. Specifically, the data is obtained by performing primary firing and hot isostatic pressing. This is a manufacturing method in which an annealing process that is a secondary baking and a tertiary baking is performed. Similarly, the data according to Comparative Example 1 in FIG. 3 is the reflectance of the phosphor corresponding to Comparative Example 1, that is, the phosphor obtained through only primary firing. Further, Comparative Example 3 shows the phosphor added with the annealing after the primary firing, and Comparative Example 4 shows the reflectance of the phosphor subjected to the hot isostatic pressing after the primary firing.

From the data of FIG. 3, in the peak wavelength range of the phosphor, the phosphor that has undergone secondary firing by hot isostatic pressing has improved reflectance compared to the phosphor that has not been subjected to secondary firing. Yes. That is, a phosphor that has been subjected to hot isostatic pressing rather than only a primary firing or a phosphor added with an annealing treatment has a lower light absorption rate to the phosphor upon emission of fluorescence by excitation, that is, It shows that energy conversion efficiency can be improved. Further, in the comparison of phosphors that have been subjected to hot isostatic pressing and further annealed (Example) or those that have not been annealed (Comparative Example 1), reflectivity Although the difference is small, as shown in Table 1 above, the characteristics were greatly changed in terms of luminance. That is, a remarkable brightness increase of 2.5 times or more was confirmed by annealing after hot isostatic pressing. That is, in the structure of the phosphor, it is considered that the effect of increasing the brightness by the annealing treatment is further exhibited by reducing the light absorption component by the hot isostatic pressing and then performing the annealing treatment firing step. An example of a light emitting device on which the phosphor of Embodiment 1 is mounted will be shown below.
(Light emitting device)

  Examples of the light emitting device include a lighting device such as a fluorescent lamp, a display device such as a display and a radar, and a liquid crystal backlight. In the following embodiments, a light-emitting device including a light-emitting element that emits light in the short wavelength region from near ultraviolet to visible as an excitation light source will be described as an example. The light emitting element is small in size, has high power efficiency, and emits bright colors. In addition, since the light emitting element is a semiconductor element, there is no fear of a broken ball. In addition, it has excellent initial drivability and is strong against vibration and repeated on / off lighting. In addition, a light-emitting device in which a light-emitting element and a phosphor having excellent light-emitting characteristics are combined is preferable.

  The excitation light source preferably has a main emission peak in the ultraviolet region having low visibility characteristics. The relationship between the human eye feeling and the light wavelength is based on the visibility characteristic, and the visibility of the light at 555 nm is the highest, and the visibility decreases toward the short wavelength and the long wavelength. For example, light in the ultraviolet region used as an excitation light source belongs to a portion having low visibility, and the light emission color of the light emitting device is substantially determined by the light emission color of the fluorescent material used. Further, even when a color shift of a light emitting element due to a change in input current or the like occurs, a color shift of a fluorescent material that emits light in the visible light region can be suppressed to be extremely small. As a result, a light emitting device with little color tone change is provided. Can do. This is because the ultraviolet region generally has a wavelength shorter than 380 nm or 400 nm, but light having a wavelength of 420 nm or less is hardly visible in terms of visual sensitivity, so that the color tone is not greatly affected. Moreover, it is because the short wavelength light has higher energy than the long wavelength light.

  In the following embodiments, an excitation light source having a main emission peak in a region on the short wavelength side of visible light can also be used. In a light emitting device that covers an excitation light source with a coating member containing a fluorescent material, light emitted from the excitation light source is transmitted without being absorbed by the fluorescent material, and the transmitted light is emitted from the coating member to the outside. When light on the short wavelength side of visible light is used as the excitation light source, the light emitted to the outside can be used effectively. Therefore, loss of light emitted from the light emitting device can be reduced, and a highly efficient light emitting device can be provided. From this, this embodiment can also use an excitation light source having a main emission peak from 420 nm to 495 nm. In this case, blue light can be emitted. Further, since light having a relatively short wavelength is not used, a light-emitting device that is less harmful to the human body can be provided.

  However, as the excitation light source, in addition to the semiconductor light emitting element, an excitation light source having an emission peak wavelength in a short wavelength region from ultraviolet to visible light, such as a mercury lamp used in an existing fluorescent lamp, can be used as appropriate. The light emitting element in this specification includes not only an element that emits visible light but also an element that emits near ultraviolet light, far ultraviolet light, or the like. Further, the “main surface” refers to a surface on the light emitting surface side from which the light of the semiconductor light emitting element is extracted with respect to the surface of each component of the light emitting device such as a package and a lead electrode.

  By the way, there are various types of light emitting devices equipped with light emitting elements, such as a shell type and a surface mount type. In general, the bullet shape refers to a shape in which the shape of the resin constituting the outer surface is formed into a bullet shape. The surface-mounting type refers to one formed by filling a light-emitting element and a resin in a concave storage portion. Examples of various light emitting devices are given below.

  4A and 4B show the light-emitting device 60 according to Embodiment 1. FIG. 4A is a perspective view of the light-emitting device 60, and FIG. 4B is the light-emitting device 60 taken along the line IVB-IVB ′ of FIG. FIG. The light emitting device 60 is a side view type light emitting device which is a kind of surface mount type. The side view type is a light emitting device that emits light from the side surface adjacent to the mounting surface of the light emitting device, and can be made thinner.

  Specifically, the light emitting device 60 of FIG. 4 has a recess 14 and the light emitting element 2 housed in the recess, and the recess 14 is filled with a resin containing the phosphor 3. The recess 14 is a part of the package 17, that is, the package 17 includes the recess 14 and a support body 16 connected to the recess 14. As shown in FIG. 4B, positive and negative lead electrodes 15 are interposed between the concave portion 14 and the support body 16 to constitute a mounting surface of the light emitting element 2 in the concave portion 14. Further, the lead electrode 15 is exposed on the outer surface side of the package 17 and is provided along this outer shape. The light emitting element 2 is mounted on and electrically connected to the lead electrode 15 in the recess 14, and can emit light by receiving power supply from the outside via the lead electrode 15. FIG. 4A shows a general state in which the light emitting device 60 is mounted. That is, the light emitting device 60 is mounted with the wide surface orthogonal to the surface on which the light emitting element 2 is mounted as the bottom surface. With the above structure, the light emitting device 60 can emit light from a direction substantially parallel to the mounting surface of the light emitting element, that is, a side surface adjacent to the mounting surface of the light emitting device.

  Hereinafter, the light emitting device 60 will be described in detail. The package 17 is integrally molded so that one end of both the positive and negative lead electrodes 15 is inserted into the package 17. That is, the package 17 has a recess 14 capable of accommodating the light emitting element 2 on the main surface side, and one end of the positive lead electrode 15 and one end of the negative lead electrode 15 are formed on the bottom surface of the recess 14. The parts are separated from each other so that their main surfaces are exposed. An insulating molding material is filled between the positive and negative lead electrodes 15. In the present invention, the shape of the light emitting surface formed on the main surface side of the light emitting device is not limited to a rectangular shape, and may be an elliptical shape. By adopting various shapes, it is possible to make the light emitting surface as large as possible while maintaining the mechanical strength of the package side wall portion forming the recess 14 and to make the light emitting device capable of irradiating a wide range even if it is thinned. Can do.

  In the light emitting device 60 of the first embodiment, the positive and negative lead electrodes 15 are inserted so that the other end protrudes from the side surface of the package. The protruding portion of the lead electrode 15 is bent toward the back side facing the main surface of the package 17 or toward the mounting surface side perpendicular to the main surface. In addition, the shape of the inner wall surface that forms the recess 14 is not particularly limited, but when the light emitting element 4 is placed, it is preferable to have a tapered shape in which the inner diameter gradually increases toward the opening. Thereby, the light emitted from the end face of the light emitting element 2 can be efficiently extracted in the direction of the emission observation surface. Further, in order to enhance the reflection of light, it is preferable to have a light reflecting function such as applying metal plating such as silver on the inner wall surface of the recess.

In the light emitting device 60 of the first embodiment, the light emitting element 4 is placed in the concave portion 14 of the package 1 configured as described above, and a light-transmitting resin is filled so as to cover the light emitting element 4 in the concave portion. Then, the sealing member 18 is formed. This translucent resin contains a phosphor 3 that is a wavelength conversion member. As the translucent resin, a silicone resin composition is preferably used, but an insulating resin composition having translucency such as an epoxy resin composition and an acrylic resin composition can also be used.
(Light emitting element)

  The light-emitting element can emit light from the ultraviolet region to the visible light region. In particular, a light emitting element having an emission peak wavelength of 240 nm to 480 nm, more preferably 290 nm to 460 nm, and more preferably 350 nm to 460 nm is used, and a light emitting layer capable of emitting light having an emission wavelength capable of efficiently exciting a fluorescent material is provided. It is preferable. This is because a phosphor with high luminous efficiency can be provided by using an excitation light source in this range. Further, by using a semiconductor light emitting element as an excitation light source, a stable light emitting device with high efficiency, high output linearity with respect to input, and strong against mechanical shock can be obtained. The light in the short wavelength region of visible light is mainly in the blue light region. Hereinafter, a nitride semiconductor light emitting device will be described as an example of the light emitting device, but the present invention is not limited to this.

  Specifically, the light emitting element is preferably a nitride semiconductor element containing In or Ga. This is because the phosphor strongly emits light in the vicinity of 495 nm to 540 nm, and thus a light emitting element in the wavelength region is required. The light emitting element emits light having an emission peak wavelength in the short wavelength region from near ultraviolet to visible light, and at least one or more phosphors are excited by the light from the light emitting element to exhibit a predetermined emission color. Further, since the light emitting element can narrow the emission spectrum width, the phosphor can efficiently excite the phosphor, and the light emission device does not substantially affect the color change from the light emitting device. Can also be released.

In the light emitting element 2 according to the first embodiment, an LED chip which is an example of a nitride semiconductor element is employed. In addition, although a well-known thing can be utilized suitably for the light emitting element 2, when setting it as the light-emitting device provided with the fluorescent substance, the semiconductor light-emitting element which can light-emit the light which excites the fluorescent substance is preferable. Examples of such a semiconductor light emitting device include various semiconductors such as ZnSe and GaN. Nitride semiconductors capable of emitting short wavelengths capable of efficiently exciting fluorescent materials (In _x Al _y Ga _1-xy N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) are preferable. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. The light emitting element 2 used in the present embodiment has positive and negative electrodes formed on the same surface side, but the positive and negative electrodes may be formed on the corresponding surfaces. Good. Further, the positive and negative electrodes do not necessarily have to be formed one by one, and two or more each may be formed.

Thus, by using the light emitted from the light emitting element as an excitation light source, an efficient light emitting device with low power consumption compared to a conventional mercury lamp can be realized. The light emitting device according to Embodiment 1 can use the phosphors of the above-described examples.
(Phosphor)

As the phosphor 3 in the first embodiment, the nitride phosphor described above is used. The phosphor 3 is preferably mixed in the resin at a substantially uniform ratio. Thereby, light without color unevenness is obtained. Further, in the nitride phosphor described above, it is highly luminous that it contains a crystal phase represented by the general formula Si _6-z Al _z O _z N _8-z with high purity and is composed of a single phase. From the point of view, it is preferable, but other crystal phases or a mixture may be contained as long as the characteristics are not deteriorated. The brightness and wavelength of the light emitted from the light emitting device 60 are determined by the particle size of the phosphor 3 sealed in the light emitting device 60, the uniformity after coating, the thickness of the resin containing the phosphor, and the like. to be influenced. Specifically, if the amount and size of the phosphor excited before the light emitted from the light emitting element 2 is emitted to the outside of the light emitting device 60 at a site in the light emitting device 60 is unevenly distributed, Color unevenness occurs. Further, in the phosphor powder, light emission is considered to occur mainly on the particle surface. Therefore, if the average particle size is generally small, a surface area per unit weight of the powder can be secured and a reduction in luminance can be avoided. Further, the small-sized phosphor can diffuse and reflect light to prevent uneven color of the emitted color. On the other hand, the large particle size phosphor improves the light conversion efficiency. Therefore, light can be extracted efficiently by controlling the amount and particle size of the phosphor.

  Further, it is more preferable that the phosphor disposed in the light emitting device 60 is resistant to heat generated from the light source and weather resistant that is not affected by the use environment. This is because the fluorescence intensity generally decreases as the temperature of the medium increases. This is because as the temperature rises, intermolecular collision increases and potential energy loss is caused by non-radiative transition deactivation.

  However, the phosphor 3 can be blended so as to be partially distributed in the resin. As an example, by placing the light-emitting element 2 close to the light-emitting element 2, the light from the light-emitting element 2 can be wavelength-converted efficiently, and a light-emitting device with excellent light-emitting efficiency can be obtained.

  Further, two or more kinds of phosphors may be contained in the sealing member 18. Thereby, the wavelength of the main light source output from the light emitting layer can be converted by the first phosphor, and light that has been wavelength-converted by the second phosphor can be obtained. By adjusting the combination of the plurality of phosphors, the main light source, the light wavelength-converted by the first phosphor, the light wavelength-converted by the second phosphor, and the main light source directly the second fluorescence Various colors can be expressed by combining light that has been wavelength-converted by the body.

In the case of the light emitting device 60 according to the first embodiment, by combining the excitation light from the LED chip, the phosphor capable of emitting green excited by the LED chip, and the phosphor capable of emitting blue or red, White light having excellent light emission characteristics can be emitted. Examples of the phosphor capable of emitting red light include (Ca _1-x Sr _x ) AlB _y SiN _{3 + y} : Eu (0 ≦ x ≦ 1.0, 0 ≦ y ≦ 0.5) or (Ca _1-z Sr _z ) ₂ Si ₅ N ₈ : Eu (0 ≦ z ≦ 1.0). By using these phosphors in combination, the half-value width of each component light corresponding to the three primary colors can be narrowed, that is, white light composed of sharp three wavelengths can be obtained. As a result, the overlap between the wavelengths is reduced, and the emission peak of each component light and the transmittance peak of the color filter can be substantially matched. Therefore, white light containing component light corresponding to the effective wavelength region is realized with high efficiency, and as a result, loss of the amount of light flux after passing through the filter can be reduced, so that the emission light with improved overall output and Become. In addition, the phosphor described above is excellent in stability at high temperature and high humidity, and thus can be a light-emitting device rich in weather resistance.

In addition, as an example of the phosphor, when the light from the light-emitting element is high-energy short-wavelength visible light, a perylene derivative that is an organic fluorescent material, (Zn, Cd) S: Cu, Al, YAG: Ce, Eu Inorganic fluorescent materials such as nitrogen-containing CaO—Al ₂ O ₃ —SiO ₂ activated by Cr and / or Cr can be appropriately employed. Similarly, in addition to nitrogen-containing CaO—Al ₂ O ₃ —SiO ₂ activated with YAG: Ce, Eu and / or Cr, for example, described in JP-A-2005-19646, JP-A-2005-8844, etc. Any of the known fluorescent materials can be used. Alkaline earth sulfide-based, thiogallate-based, thiosilicate-based, zinc sulfide-based, and oxysulfide-based sulfide phosphors can also be selected as appropriate. For example, MS: Re (M is one or more selected from the group consisting of Mg, Ca, Sr and Ba, and Re is one or more selected from Eu and Ce) as the alkaline earth sulfide phosphor As the thiogallate phosphor, MN ₂ S ₄ : Re (M is one or more selected from Mg, Ca, Sr and Ba, N is one or more selected from Al, Ga, In and Y, Re Is one or more selected from Eu and Ce), and the thiosilicate phosphor is M ₂ LS ₄ : Re (M is one or more selected from Mg, Ca, Ba, Sr, Ba, and L is 1 or more selected from Si, Ge and Sn, Re is one or more selected from Eu and Ce), etc., and ZnS: K (K is selected from Ag, Cu and Al) as the zinc sulfide-based phosphor 1 Ln as oxysulfide phosphors ₂ O ₂ S: Re (Ln is one or more selected from Y, La and Gd, and Re is one or more selected from Eu and Ce).

In addition, the sealing member 18 can appropriately contain an additive member. For example, by including a light diffusing material, the directivity from the light emitting element can be relaxed and the viewing angle can be increased.
(Embodiment 2)

  Further, as a light emitting device according to Embodiment 2 of the present invention, a surface mount type light emitting device 70 is shown in FIG. 5A is a plan view of the light emitting device 70, and FIG. 5B is a cross-sectional view. As the light emitting element 71, a nitride semiconductor light emitting element excited by ultraviolet light can be used. The light emitting element 71 may be a blue excited nitride semiconductor light emitting element. Here, the light emitting element 71 excited by ultraviolet light will be described as an example. The light emitting element 71 uses a nitride semiconductor light emitting element having an InGaN semiconductor with an emission peak wavelength of about 370 nm as a light emitting layer. The light-emitting element 71 includes a p-type semiconductor layer and an n-type semiconductor layer (not shown), and a conductive wire 74 connected to the lead electrode 72 in the p-type semiconductor layer and the n-type semiconductor layer. Is formed. An insulating sealing material 73 is formed so as to cover the outer periphery of the lead electrode 72 to prevent a short circuit. Above the light emitting element 71, a translucent window 77 extending from a Kovar lid 76 at the top of the package 75 is provided. A uniform mixture of the phosphor 3 and the coating member 79 is applied to almost the entire inner surface of the translucent window portion 77.

  Next, each electrode of the die-bonded light emitting element 71 and each lead electrode 72 exposed from the bottom surface of the package recess are electrically connected by a conductive wire 74 such as an Ag wire. After sufficiently removing moisture in the recess of the package, sealing is performed with a Kovar lid 76 having a glass window 77 at the center, and seam welding is performed. In the glass window portion, a sialon phosphor 3 as a wavelength conversion member is previously contained in a slurry composed of 90 wt% nitrocellulose and 10 wt% γ-alumina, and is applied to the back surface of the translucent window portion 77 of the lid 76. The color conversion member is constituted by heating and curing at 220 ° C. for 30 minutes. The light output from the light emitting element 71 of the light emitting device 70 formed in this way excites the phosphor 3 and can be a light emitting device capable of emitting a desired color with high luminance. This makes it possible to obtain a light emitting device with extremely simple chromaticity adjustment and excellent mass productivity and reliability.

In the second embodiment, the light in the ultraviolet region used as the excitation light source belongs to a portion having low visibility, and the light emission color of the light emitting device is substantially determined by the light emission color of the fluorescent material used. For example, light emission capable of emitting high-intensity white light by mounting the phosphor described in Embodiment 1 on the light-emitting element in Embodiment 2 and further mounting the phosphor capable of emitting blue and red light. Can with equipment. Further, in the light emitting device of Embodiment 2, even when a color shift of the light emitting element due to a change in input current or the like occurs, the color shift of the fluorescent material that emits light in the visible light region can be suppressed to a very small value. Thus, a light-emitting device with little change in color tone can be provided. Although the ultraviolet region generally has a wavelength shorter than 380 nm or 400 nm, light having a wavelength of 420 nm or less is hardly visible in terms of visibility, so that the color tone is not greatly affected.
(Embodiment 3)

  FIG. 6A is a perspective view of the light emitting device 40 according to Embodiment 3 of the present invention. FIG. 6B is a cross-sectional view taken along the line VIB-VIB ′ of the semiconductor light emitting device 40 shown in FIG. Hereinafter, an outline of the light emitting device 40 according to Embodiment 3 will be described with reference to FIGS. 6A and 6B. The light emitting device 40 is configured such that a package 12 having a space that opens in a substantially concave shape toward the top is mounted on the lead frame 4. Further, a plurality of light emitting elements 2 are mounted on the exposed lead frame 4 in the space of the package 12. That is, the package 12 is a frame that surrounds the light emitting element 2. In addition, a protective element 13 such as a Zener diode, which is energized when a voltage higher than a specified voltage is applied, is also placed in the open space of the package 12. Further, the light emitting element 2 is electrically connected to the lead frame 4 via bonding wires 5 and bumps. In addition, the open space of the package 12 is filled with the sealing resin 6.

The phosphor 3 contained in the package 12 is shown in FIG. 6B (the phosphor 3 in FIG. 6A is omitted). As this phosphor 3, the above-mentioned sialon phosphor can be used, and the content of the phosphor in the resin 6 is the same as in the first embodiment.
(Embodiment 4)

FIG. 7 shows a bullet-type light emitting device 1 according to the fourth embodiment. The light-emitting device 1 is in a concave cup 10 formed by a lead frame 4 made of a conductive member. The light-emitting device 2 is placed on the lead frame 4 and is emitted from the light-emitting element 2. A phosphor 3 that converts the wavelength of at least a part of the emitted light. The phosphor of the first embodiment can be mounted on the phosphor 3 as in the second embodiment. The light-emitting element 2 is a light-emitting element having an emission peak wavelength at about 360 nm to 460 nm. Positive and negative electrodes 9 formed on the light emitting element 2 are electrically connected to the lead frame 4 via conductive bonding wires 5. Further, the light emitting element 2, the lead frame 4, and the bonding wire 5 are covered with a shell-shaped mold 11 so that the lead frame electrode 4 a which is a part of the lead frame 4 protrudes. The mold 11 is filled with a light-transmitting resin 6, and the resin 6 contains a phosphor 3 that is a wavelength conversion member. As the resin 6, it is preferable to use a silicone resin composition such as a silicone resin having a siloxane bond in the molecule or a siloxane skeleton fluororesin. Thereby, it can be set as the sealing resin excellent in light resistance and heat resistance. On the other hand, a silicone resin generally has a high gas permeability due to a long bond distance between elements, and moisture in an environmental atmosphere is easily transmitted. Therefore, it tends to facilitate the elution of the phosphor components under high temperature and high humidity. However, since the phosphor of the present invention suppresses the elution of chlorine from the phosphor itself, the chlorine component that permeates the silicone resin can be significantly reduced even when combined with the silicone resin composition. That is, combining the phosphor of the present invention with a silicone resin is preferable because the advantages of the silicone resin can be enjoyed while avoiding the influence of chlorine on the member. Moreover, the resin 6 can also use the insulating resin composition which has translucency, such as an epoxy resin composition and an acrylic resin composition. By supplying electric power from an external power source to the lead frame electrode 4 a protruding from the resin 6, light is emitted from the light emitting layer 8 contained in the layer of the light emitting element 2. The emission peak wavelength output from the light emitting layer 8 has an emission spectrum near 495 nm or less in the ultraviolet to blue region. Part of the emitted light excites the phosphor 3, and light having a wavelength different from the wavelength of the main light source from the light emitting layer 8 is obtained.
(Embodiment 5)

  Next, a light emitting device 20 according to Embodiment 5 of the present invention is shown in FIG. In this light emitting device 20, the same members as those in the light emitting device 1 according to Embodiment 4 are denoted by the same reference numerals, and the description thereof is omitted. In the light emitting device 20, the resin 6 containing the phosphor 3 is filled only in the concave cup 10 molded by the lead frame 4. The phosphor 3 is not contained in the resin 6 filled inside the mold 11 and outside the cup 10. The resin containing phosphor 3 and the resin not containing are preferably the same, but they may be different. In the case of different types of resins, the softness can be changed using the difference in temperature required for each resin to cure.

  In the light emitting device 20, since the light emitting element 2 is placed at substantially the center of the bottom surface forming the opening in the cup 10, the light emitting element 2 is embedded in the resin 6 including the phosphor 3. In order for the light from the light emitting layer 8 to be wavelength-converted by the phosphor 3 without unevenness, the light from the light emitting element has only to pass through the phosphor-containing resin uniformly. That is, the phosphor-containing resin film through which light from the light emitting layer 8 passes may be made uniform. Therefore, the size of the cup 10 and the mounting position of the light emitting element 2 may be determined so that the distance from the periphery of the light emitting element 2 to the wall surface and upper part of the cup 10 is uniform. With this light emitting device 20, it becomes easy to uniformly adjust the film thickness of the resin 6 containing the phosphor 3.

Further, similarly to the first embodiment, the phosphor 3 can be blended so as to be partially unevenly distributed in the resin. As an example, the light emitting device 50 shown in FIG. 8B is formed by forming a phosphor layer having a substantially uniform thickness in the vicinity of the periphery of the light emitting element 2. As a result, the amount of phosphor through which light emitted from the light emitting element 2 passes to the periphery is substantially constant, that is, since the same amount of phosphor is wavelength-converted, a light emitting device with reduced color unevenness can be obtained. Further, the type of phosphor 3 to be placed can be the same as in the second embodiment.
(Embodiment 6)

  Furthermore, as a light-emitting device according to Embodiment 6 of the present invention, a cap-type light-emitting device 30 is shown in FIG. As the light emitting element 2, a light emitting element having an emission peak wavelength at about 400 nm is used. The light emitting device 30 is configured by covering a cap 31 made of a light transmissive resin in which the phosphor 3 is dispersed on the surface of the mold 11 of the light emitting device 20 of the second embodiment.

  The cap 31 has the phosphor 3a uniformly dispersed in the light transmissive resin 6a. The resin 6 a containing the phosphor 3 a is molded into a shape that fits into the shape of the outer surface of the mold 11 of the light emitting device 30. Alternatively, a manufacturing method is also possible in which a light-transmitting resin 6a containing a predetermined in-frame phosphor is put, and then the light emitting device 30 is pushed into the mold and molded. As a specific material of the resin 6a of the cap 31, a transparent resin, silica gel, glass, an inorganic binder, etc. excellent in temperature characteristics and weather resistance such as an epoxy resin, a urea resin, and a silicone resin are used. In addition to the above, thermosetting resins such as melamine resins and phenol resins can be used. In addition, thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene, thermoplastic rubbers such as styrene-butadiene block copolymer, segmented polyurethane, and the like can also be used. Further, a diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like may be contained together with the phosphor. Moreover, you may contain a light stabilizer and a coloring agent. The phosphor 3a used for the cap 31 can be not only one type but also a mixture of a plurality of phosphors or a layered structure.

  In the light emitting device 30, the phosphor 3 a can be contained only in the resin 6 a in the cap 31, but in addition to this, the cup 6 may be filled with the resin 6 containing the phosphor 3. The types of the phosphors 3 and 3a may be the same or different, and each of the resins 6 and 6a may have a plurality of phosphors. As a result, various emission colors can be realized. An example is a light emitting device that emits white light. The light emitted from the light emitting element 2 excites the phosphor 3 and emits light from blue green to green and from yellow to red. A part of the light emitted from the phosphor 3 excites the phosphor 3a of the cap 31, and emits light from green to a yellow region. Due to the mixed color light of these phosphors, white light is emitted from the surface of the cap 31 to the outside. The various phosphors to be mounted are the same as in the first embodiment.

  The method for producing the phosphor of the present invention is suitable for white illumination with excellent emission characteristics using a blue light emitting diode or an ultraviolet light emitting diode as a light source, such as a fluorescent display tube, display, PDP, CRT, FL, FED, and projection tube. It can be suitably used for light sources, LED displays, backlight sources, traffic lights, illumination switches, various sensors, various indicators, and the like.

DESCRIPTION OF SYMBOLS 1, 20, 30, 40, 50, 60, 70 ... Light emitting device 2 ... Light emitting element 3 ... Phosphor 3a ... Small particle fluorescent substance 4 ... Lead frame 4a ... Lead frame electrode 5 ... Bonding wire 6 ... Resin 6a ... Resin 8 ... Light emitting layer 9 ... Electrode 10 ... Cup 11 ... Mold 12 ... Package 13 ... Protective element 14 ... Recess 15 ... Lead electrode 16 ... Support 17 ... Package 18 ... Sealing member 31 ... Cap 71 ... Light emitting element 72 ... Lead electrode 73 ... Insulating encapsulant 74 ... Conductive wire 75 ... Package 76 ... Kovar lid 77 ... Translucent window (glass window)
79 ... Coating member

Claims (8)

The general formula of the composition is Si _6-z Al _z O _z N _8-z : Re (Re is an activator containing at least one selected from the group consisting of manganese, cerium and europium, and 0 <Z < 4.2) A method for producing the phosphor shown in FIG.
Firing the composition represented by the general formula at a temperature of 1500 ° C. or more and 2200 ° C. or less while applying isotropic pressure in a nitrogen atmosphere of 100 MPa or more;
And a step of performing annealing treatment by heating the fired fired body to 1400 ° C. or more and 2000 ° C. or less in an atmosphere containing hydrogen. The method for producing a phosphor according to claim 1, further comprising:
Prior to the firing step, a method for producing a phosphor including a step of firing the mixture containing a silicon compound, an aluminum compound, and the activator compound to obtain the composition. In the manufacturing method of the fluorescent substance according to claim 2,
The method for producing a phosphor, wherein the step of obtaining the composition is a step of baking the mixture at a temperature of 1900 ° C. or higher and 2200 ° C. or lower while isotropically applying pressure in a nitrogen atmosphere of 100 MPa or higher. In the manufacturing method of the fluorescent substance according to claim 3,
A method for producing a phosphor, wherein the temperature holding time is 4 hours or more. In the manufacturing method of the fluorescent substance according to any one of claims 2 to 4,
A method for producing a phosphor, wherein the silicon compound is silicon nitride, the aluminum compound is aluminum nitride, and the activator compound is europium oxide. In the manufacturing method of the fluorescent substance according to claim 2,
The method for producing a phosphor, wherein the step of obtaining the composition is a step of firing the mixture in a nitrogen atmosphere having a pressure of 0.5 MPa to 207 MPa. In the manufacturing method of the fluorescent substance of Claim 2 or 6,
The method for producing a phosphor, wherein the step of obtaining the composition is a step of baking the mixture at a temperature of 1900 ° C. or higher and 2200 ° C. or lower. In the manufacturing method of the fluorescent substance according to any one of claims 2 to 7,
The manufacturing method of the fluorescent substance whose average particle diameters of the compound of the said silicon compound, the said aluminum compound, and the said activator are 0.1 micrometer or more and 15 micrometers or less, respectively.

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